Low-grade appendiceal mucinous neoplasm (LAMN) is a rare subtype of appendiceal pathology characterized by epithelial hyperplasia, cellular atypia, and mucinous accumulation within the appendiceal lumen, leading to obstructive expansion of the organ. Representing a mere 0.2% to 0.3% of all appendectomies and approximately 0.5% of gastrointestinal tumors, LAMN poses diagnostic challenges in surgical practice.

We conducted a retrospective analysis of a patient with the appendiceal neoplasm. A 39-year-old female presented to Jiaozhou Hospital, East Hospital Affiliated to Tongji University on July 9, 2022, complaining of a nine-day history of right lower abdominal pain, distension, and nausea. Physical examination revealed a palpable measuring 15 × 6 cm in the right lower quadrant, accompanied by tenderness, rebound tenderness, and muscular guarding.

Histopathological examination confirmed the diagnosis of a LAMN without evidence of lymphovascular invasion, serosal, or mesenteric infiltration.

After antiinflammatory therapy and comprehensive assessment, the neoplasm was excised through three-dimensional laparoscopic surgery.

No recurrence was observed during an 32-month postoperative follow-up period.

Despite its rarity, LAMN warrants clinical attention due to its nonspecific symptoms. Computed tomography scans significantly improve preoperative diagnostic accuracy, with pathological diagnosis serving as the gold standard. Surgical intervention is the preferred treatment option, albeit controversies persist regarding surgical extent and the utilization of preoperative and postoperative chemotherapy.

Pseudomyxoma peritonei (PMP) is a rare disease characterized by diffuse peritoneal invasion of multifocal mucinous deposits. Gold standard treatment involves cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC). We aimed to compare the outcomes of operated PMP patients in a low-volume center, with those of high-volume centers and using other regimens.

Retrospective analysis was conducted for PMP patients treated by CRS + HIPEC (using the Elias high-dose Oxaliplatin HIPEC regimen) over a 15-year period (January 2007 - December 2021) at the Jules Bordet Institute - H.U.B.

32 patients were included. Pathology results were: 21.9% acellular mucin, 34.4% low-grade, and 43.7% high-grade. The median peritoneal cancer index was 24 (range 3-36). The median follow-up was 58 months. The rate of major complications (Clavien-Dindo III/IV) was 41% and postoperative mortality was 3%. Mean disease-free survival (DFS) was estimated at 40 +/- 4 months (standard deviation (SD)) while overall survival (OS) was 122 +/- 9 months (SD). DFS reached a plateau of 44.5% at 5 and 10 years and OS was 92.3% and 76.2% respectively. Statistical analysis showed low-grade PMP to be predictive of better DFS and OS (p = 0.0111 and p = 0.0293 respectively). We also found that female gender was predictive of better DFS (p = 0.0262).

Our postoperative morbidity and mortality rates, DFS, and OS were similar to those reported in the literature for high-volume PMP centers. Our theory is that surgical proficiency can be more attributed to the surgeon's CRS experience, regardless of the nature of the disease.

Cytoreductive surgery (CRS) with Hyperthermic Intra-peritoneal Chemotherapy (HIPEC) has become a successful, potentially curative, treatment option for peritoneal surface malignancies (PSM). CRS and HIPEC (CRS/HIPEC) are performed with curative intent for several intra-peritoneal pathologies. An increasing number of patients with PSM are diagnosed at a relatively young age. Given the long-term survival in some patients following CRS/HIPEC, the reproductive health of patients in this age group requires consideration.

Surgical oncology teams participating in the Peritoneal Surface Oncology Group International (PSOGI) were offered the opportunity to share their experience and data regarding the obstetric outcomes of female patients who had undergone CRS/HIPEC.

Nineteen (19) patients were reported to have had a baby following CRS/HIPEC. The median interval between CRS/HIPEC and pregnancy was 37 months, and 16 patients had a normal vaginal delivery. All of the newborns were healthy, without medical issues attributed to CRS or HIPEC chemotherapy. Overall, 89 % of mothers had no evidence of disease at their last follow-up.

Successful pregnancies following CRS/HIPEC are seldom reported in the literature, and fertility preservation is not uniformly discussed. Data from this international collaboration highlights the reproductive potential in patients with PSM following CRS/HIPEC and the value of pre-operative obstetric and fertility advice and management to achieve that end.

Improved understanding about the pathobiology of appendiceal cancers (AC) and resulting metastasis is required for the development of novel treatments. The tumor microenvironment in AC is heterogeneous and incompletely characterized. The objective of this study was to leverage spatial high-plex technology to evaluate the transcriptomic landscape of epithelial and stromal cells in primary AC tumors, adjacent normal appendix, and corresponding peritoneal metastasis.

A tissue microarray (TMA) containing cores from 14 unique patients having matched primary tumor, adjacent normal appendix, and peritoneal metastases was analyzed with digital spatial profiling (NanoString, GeoMx) using pancytokeratin (PCK) to delineate stroma (PCK-) from epithelium (PCK+). Then RNA sequencing was performed to measure transcript abundance separately within the stromal and epithelial compartments.

Transcriptomic analysis demonstrated differences between tumor and stromal compartments in both primary tumor and metastatic sites. Primary and metastatic tumor stroma (PCK-) demonstrated greater expression of ribosomal biogenesis pathways than normal appendiceal tissue. Primary and metastatic tumors were generally similar with respect to transcription. However, within the epithelial compartment (PCK+), peritoneal metastases exhibited upregulated cytoskeletal and collagen metabolism pathways/genes compared with primary tumor.

The study data indicated that although appendiceal peritoneal disease is transcriptionally similar to the primary tumor, potentially important distinctions exist between metastatic and primary disease. Differences appear to be driven predominantly by changes in collagen metabolism at the peritoneal site. A better understanding of both tumor and stromal compartments of metastatic disease will be essential to improving therapeutic options, specifically systemic treatment, which is characteristically ineffective.

Pseudomyxoma peritonei (PMP) is a rare neoplasm coursing with uncontrollable mucus accumulation, with a high relapse rate. RNA biology processes have emerged as new players in cancer development and progression, nevertheless their role in PMP remains unknown. In this study, we aimed to examine RNA-regulatory machineries in PMP and their potential contribution to this disease progression. We analyzed 62 splicing-related genes, 27 RNA exosome and 21 nonsense-mediated decay genes, in a cohort of 29 patients using a microfluidic array, comparing tumor and control/reference tissues, together with external RNA-seq and proteomic data. Our results revealed a profound dysregulation of key components, which correlated to relevant clinical parameters and enabled to distinguish between tumor and control tissues. In vitro splicing inhibition using Pladienolide-B, as well as the modulation of specific splicing factors, reduced aggressiveness parameters, enhanced the effect of clinically used drugs, and revealed a strong correlation between dysregulated genes and key cancer-related genes. This inhibition also affected mucin secretion and mucin variants production. Collectively, our findings provide the first evidence for dysregulation of the genes of pivotal RNA-regulatory processes in PMP, implying that these targetable mechanisms may be functionally altered and play a role in the disease. Hence, a thorough understanding of its RNA biology could aid in the discovery of new clinically actionable vulnerabilities in this rare disease.

Pseudomyxoma peritonei (PMP) is a distinct form of peritoneal malignancy characterized by diffuse intra-abdominal gelatinous ascites, with an estimated incidence of 1-3 per 1000000. PMP is predominantly secondary to appendiceal mucinous neoplasms, with rarer origins including the ovaries, colon, and urachus. However, PMP originating from small intestine is extremely rare.

A 60-year-old male patient presented with anorexia and abdominal distension. Computed tomography revealed the presence of abdominopelvic effusions and multiple intra-abdominal space-occupying lesions. Ultrasound-guided aspiration indicated that the aspirated tissue was mucinous. Exploratory laparoscopy and tissue biopsy identified diffuse tumor nodules in peritoneum, omentum, pelvic region, intestinal walls, and mesentery. Histopathological analysis of the resected tumors confirmed the presence of mucinous adenocarcinoma, but the primary lesion was difficult to determine. The patient was referred to our center for further treatment and underwent cytoreductive surgery (CRS) combined with hyperthermic intraperitoneal chemotherapy (HIPEC) under general anesthesia. The intraoperative peritoneal cancer index was 30. The surgery lasted 8 hours, with a blood loss of about 600 mL. A complete cytoreduction (CCR0) was achieved. No serious complications occurred after surgery, and the patient's condition was good during the telephone follow-up. Postoperative pathology confirmed the diagnosis of small intestinal mucinous adenocarcinoma at proximal jejunum, which was complicated by high-grade PMP.

PMP originating from small intestine is an exceptionally rare entity that exhibits non-specific clinical features. The preferred treatment is CRS + HIPEC.

Histologic grade is a key predictor for pseudomyxoma peritonei (PMP) of appendiceal origin that is used to guide clinical management. However, some tumors demonstrate disease behavior that deviates from their histologic grade. A recent study suggested that TP53, GNAS , and RAS mutation analysis could stratify tumors into distinct molecular groups with different prognosis. We investigated molecular alterations in 114 patients with PMP of appendiceal origin who were uniformly treated with cytoreductive surgery with intraperitoneal chemotherapy (CRS+IPCT). Tumors were separated into 4 groups based on their predominant genomic alteration: RAS -mut, GNAS -mut, TP53 -mut, and triple-negative ( RAS/GNAS/TP53 -wildtype). The results were correlated with World Health Organization (WHO) grade, peritoneal carcinomatosis index (PCI), completeness of cytoreduction (CC) score, and overall survival (OS) from the time of CRS+IPCT using multivariate Cox proportional hazard analysis. Fifty percent of TP53 -mut were WHO grade 3 compared with 38% triple-negative, 10% RAS -mut, and 7% GNAS -mut tumors ( P <0.001). The TP53 -mut group exhibited a significantly reduced OS compared with other groups ( P <0.001). No significant OS difference was identified between RAS -mut, GNAS -mut, and triple-negative groups ( P >0.05). In grade 3 PMP, TP53 -mut was significantly associated with reduced OS ( P =0.002). In the multivariate analysis for OS after CRS+IPCT, TP53 -mut [hazard ratio (HR) 3.23, P =0.004] and WHO grade (grade 2 HR 2.73, P =0.03 and grade 3 HR 5.67, P <0.001) were the only independent predictors of survival. Our results suggest that, in addition to tumor grade, TP53 status may help to provide a more patient-centered approach in guiding therapy in PMP.

Localized cystic lymphangiomas (CL) are rare benign tumors deriving from the lymphatic system. CL is diagnosed more frequently in children than in the adult population and, although commonly affecting the cervical and axillary regions, can develop in various parts of the body. Abdominal cystic lymphangioma (ACL) comprises less than 5% of all CL cases.

A 35-year-old female patient with a history of benign appendectomy in childhood was transferred to our tertiary center for the operative management of a suspected extensive pseudomyxoma peritonei (PMP). In accordance with the multidisciplinary team discussion, cytoreductive surgery with hyperthermic intraperitoneal chemotherapy was planned. Intraoperatively, a typical "jelly belly" with high disease burden throughout the abdominal cavity and the small pelvis was found. A multi-visceral resection with complete cytoreduction (CCR 0) was performed. The postoperative histopathological findings revealed a diffuse, partially cystic lymphangiomatosis involving the peritoneum extensively without evidence of PMP or malignancy.

ACLs are uncommon in the adult population, and diffuse peritoneal involvement is even rarer. Surgical management with complete resection is the preferred treatment option. Other benign cysts, as well as infectious diseases and malignancy, should be considered during the preoperative workup.

Pseudomyxoma peritonei (PMP), a rare condition characterized by mucinous ascites in the peritoneal cavity, often leads to a poor prognosis. However, omics profiling of this disease remains significantly underexplored. Here, we present single-cell transcriptomic profiling of five PMP cases to identify cell type-specific gene features associated with PMP pathogenesis. Additionally, we provide bulk RNA-seq datasets from two independent cohorts: 19 fresh frozen tissue samples (12 PMPs) and 34 formalin-fixed paraffin-embedded (FFPE) samples (25 PMPs). We also offer protein expression data from a tissue microarray (TMA) analysis of 90 samples (45 PMPs). Our single-cell and bulk transcriptomic profiles, along with TMA verifications, reveal the cellular diversity of PMP, highlighting the coexistence of epithelial and mesenchymal characteristics within PMP cells. These datasets enhance our understanding of PMP pathogenesis and provide a valuable resource for uncovering the intricate molecular landscape of PMP, with the potential to improve clinical utility through further research.

Foreign body granuloma (FBG) is an inflammatory reaction to an exogenous agent. This entity is well known on the cutaneous organ but very rarely described in the abdominal cavity. We report three clinical cases of intraperitoneal FBG following major debulking of pseudomyxoma and intraperitoneal hyperthermia chemotherapy. The symptoms of FBG were a prolonged postoperative ileus (POI) requiring complex repeat surgery. The intestine was retracted by fibrous tissue with several small granulomas at the center. The granulomatous reaction was established by histopathology and the foreign body was clearly and secondarily identified as gauze fibers. Such cases have never been described before and open discussion is needed about the obstruction mechanism, the role played by large peritonectomies, the impact of the COVID-19 epidemic on malfunctions in material devices usually considered safe, and methods to ensure patient safety.

Pseudomyxoma peritonei (PMP) is a rare malignancy that lacks a highly sensitive and specific biomarker for its diagnosis. Identifying reliable serum markers is crucial for improving the diagnostic accuracy and management of PMP. This study aims to explore the diagnostic value of serum growth differentiation factor 15 (GDF-15) in patients with PMP.

We carried on a 1:1 matched case-control study. 44 patients with PMP hospitalized in Aerospace Center Hospital were recruited as cases, and 44 sex- and age-matched apparently healthy participants were selected as controls. The serum GDF-15 concentrations were tested using an ELISA method. The diagnostic value of GDF-15 in PMP patients was assessed by receiver operating characteristic (ROC) curve analysis.

The median serum GDF-15 level in PMP patients was 1192.77 (843.03-1879.06) pg/mL, notably higher than that in healthy controls [533.27 (410.46-641.47) pg/mL] (P<0.001). The area under the curve (AUC) of serum GDF-15 for PMP diagnosis was 0.907, the optimal diagnostic threshold value was 644.58 pg/mL, the sensitivity was 93.18 %, and the specificity was 77.27 %. The AUC of GDF-15 combined with carbohydrate antigen 125 (CA125) was larger than that of GDF-15 alone (P=0.027), and the sensitivity and specificity achieved 86.36 % and 95.45 %. GDF-15 levels showed a significant correlation with age (P=0.042), with younger PMP patients exhibiting notably lower concentrations of GDF-15 compared to older patients.

Serum GDF-15 could become a new marker for the PMP diagnosis. The combination of GDF-15 and CA125 demonstrated superior diagnostic performance for PMP compared to GDF-15 alone, achieving a sensitivity of 86.36% and a specificity of 95.45%.

We aimed to present a case of two mesocolonic hydatid cysts that mimicked the presentation of peritoneal pseudomyxoma. Hydatidosis is a zoonotic parasitic infection caused by the cestode Echinococcus spp., whose larval stage affects various organs. The present case describes a 40-year-old male patient who presented with severe lower abdominal pain and was diagnosed with acute appendicitis. The patient underwent an appendectomy and was later referred to an oncology surgery clinic because of imaging findings suggestive of peritoneal pseudomyxoma or carcinomatosis. A video-assisted laparoscopic procedure revealed two cysts and microscopic findings confirmed hydatid cysts. The patient was from a hydatidosis-endemic region of southern Brazil. This case highlights the diagnostic challenges and the need for a multidisciplinary approach and careful histopathological analysis in patients with complex abdominal conditions. This also demonstrates the importance of disseminating knowledge about this condition and its management.

PMP is a rare clinical syndrome characterized by the accumulation of mucinous material in the peritoneal cavity. The combination of CRS and HIPEC is the standard treatment, known to improve survival outcomes. However, follow-up adherence is critical for early detection of recurrence and extending survival. This study is the first to specifically investigate postoperative follow-up adherence in PMP patients treated with CRS and HIPEC.

To explore the socio-demographic and clinical determinants of follow-up adherence and its impact on survival in PMP patients treated with CRS and HIPEC.

This single-center, six-year retrospective study included 111 PMP patients who underwent CRS and HIPEC. Patients were categorized into compliant (control) and non-compliant (study) groups. Follow-up was initiated by the physician, with patients returning for regular visits as recommended. Kaplan-Meier analysis was used to evaluate survival outcomes, while univariate analysis identified factors influencing follow-up adherence.

Among 111 patients, 32 died by August 2024, with 1-, 3-, and 5-year survival rates of 88%, 66%, and 53%, respectively. High PCI scores (P < 0.001) and poorer histopathological types (P = 0.002) were significant predictors of reduced survival. Non-compliance with follow-up showed a trend toward decreased survival (P = 0.07). Significant risk factors for non-compliance included lower ASA scores (P = 0.020), middle- and low-income levels (P = 0.034), and parental survival status (P = 0.003). Middle- and low-income patients also experienced longer delays in seeking medical advice and had fewer cases detected through routine health screenings (P = 0.019).

Follow-up compliance has a potential impact on survival outcomes in PMP patients treated with CRS and HIPEC. Socio-demographic factors significantly influence adherence, highlighting the need for tailored interventions to enhance patient management.

Pseudomyxoma peritonei (PMP) is a rare malignant peritoneal tumor that readily recurs and metastasizes. Studies have shown that cancer stem cells (CSCs) play an important role in tumor recurrence, metastasis, and prognosis.

In this study, our aim was to isolate CSCs from various tissues of PMP patients and compare their proliferation, migration, and anti-inflammatory abilities.

We identified CSCs subsets with markers CD133+, CD166+, and CD133+/CD166+ at the gene level using single-cell mRNA sequencing (scRNA-seq). Appendiceal CSCs (AC), peritoneal CSCs (PC), and mucous CSCs (MC) were obtained using MACSQuant Tyto sorting technology and FlowSight imaging flow cytometry. The cells were cultured and markers were identified. Finally, the functional phenotypes of the three cell types were compared.

CSCs content was highest in the appendiceal tumor tissue and lowest in the mucous tissue. The cell viability rate of the sorted CSCs was above 98%, and the positive rate of CD133+ and CD166+ was 70-80%, and CD133+/CD166+ was about 30%. Among the three types of CSCs, MC had the highest proliferation ability, and TNF-α has the greatest inhibitory effect on AC migration.

AC in patients was more inert and anti-inflammatory, whereas abdominal cavity MC and PC were more active. This study revealed the biological characteristics of CSCs in different tumor tissues of patients with PMP, providing a reference for future targeted CSCs therapy.

Mucocele of the appendix and pseudomyxoma peritonei are rare diseases. The clinical findings are nonspecific in the early stages of the disease. The sequelae of appendiceal mucocele, its perforation, and extensive peritoneal involvement via pseudomyxoma peritonei (jelly belly) are repeatedly described in the literature. We present the typical findings in the natural history of the disease.

Pseudomyxoma peritonei (PP) is a rare condition, and differentiating between primary and secondary ovarian causes is crucial for determining the appropriate oncological therapy. Given the resistance of ovarian mucinous carcinoma to standard platinum-based chemotherapy, the objective of this review is to present the current therapeutic approaches and summarize the emerging trends in the treatment of this disease.

The authors conducted an exhaustive evaluation of studies published over a 14-year period (June 2010-May 2024) concerning pseudomyxoma peritonei, mucinous ovarian carcinoma, ovarian causes of PP, and ovarian cancer using the following databases: PubMed, Scopus, and Science Direct. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed. The results were organized into seven subchapters and analyzed.

The analyzed studies present surgery followed by HIPEC as the current therapy with the best long-term survival results. However, the oncological treatment is unsatisfactory, and the choice of therapy depending on the primary origin of the tumor becomes particularly important. For the differential diagnosis between pseudomyxoma due to a gastrointestinal cause and that of ovarian origin, genetic analyses are recommended; these include the characteristics of the mucin present in the lesion, as the therapeutic response can have contradictory results depending on the primary origin of the tumor.

Surgery followed by HIPEC remains the standard for resectable cases. However, oncological treatment has controversial results in the case of mucinous ovarian carcinoma compared to other types of ovarian cancer and to metastatic ovarian tumors associated with pseudomyxoma of the peritoneum. Based on the articles included in this review, it was found that the current trend is the study of mucin as a resistance factor against chemotherapy based on platinum products and the targeting of oncological therapy according to the tumor's genetic characteristics.

Currently, the primary surgical treatment for pseudomyxoma peritonei (PMP) is cytoreductive surgery (CRS) combined with hyperthermic intraperitoneal chemotherapy (HIPEC). The perioperative period is frequently accompanied by severe pain. Erector spinae plane block (ESPB) can enhance analgesia for abdominal surgery. The purpose of this study was to compare the analgesic effects of bilateral multiple-injection ESPB in patients with PMP.

Fifty patients with PMP were randomly divided into two groups: the ESPB combined with general anesthesia group (Group E) and the general anesthesia alone group (Group C). Prior to the induction, patients in Group E underwent ESPB at the T7 and T11 levels. The primary outcome was the visual analog scale (VAS) scores during rest at 6 h post-extubation. Secondary outcomes included intraoperative and postoperative opioid consumption, time for first rescue analgesia, frequency distribution of rescue analgesia, incidence of nausea and vomiting, adverse events associated with ESPB.

The Visual Analogue Scale (VAS) scores in Group E were significantly lower compared to Group C at immediate post-extubation (1.6 ± 0.9 vs. 2.4 ± 1.2, P = 0.008), and at 2 (1.9 ± 1.2 vs. 3.2 ± 1.1, P < 0.001), 4 (2.4 ± 1.5 vs. 3.7 ± 1.0, P = 0.001), and 6 h (2.7 ± 1.1 vs. 3.8 ± 1.4, P = 0.004) post-extubation during rest. Similarly, the VAS scores in Group E were significantly lower than those in Group C at immediate post-extubation (3.0 ± 1.4 vs. 4.6 ± 1.2, P < 0.001), and at 2 (3.8 ± 1.7 vs. 4.9 ± 1.4, P = 0.019), 4 (3.5 ± 1.3 vs. 5.3 ± 1.5, P < 0.001), and 6 h (3.9 ± 1.8 vs. 4.9 ± 1.3, P = 0.004) post-extubation during movement. In Group E, the intraoperative remifentanil administration (2319.3 ± 1089.5 vs. 2984.6 ± 796.1, P = 0.017) and the amount of rescue analgesia within 2 h post-extubation (0 vs. 4, P = 0.037) were significantly less than in Group C, and the first rescue analgesia time was shorter as well (231.4 ± 147.5 vs. 668.8 ± 416.7, P < 0.001).

Compared to general anesthesia alone, bilateral multiple-injection ESPB with 0.2% ropivacaine can enhance analgesia and reduce opioid administration in patients with PMP. However, the duration of analgesia with ESPB is relatively short due to the low concentration of the local anesthetic used.

Chinese Clinical Trial Registry, ChiCTR2300069504, 20/03/2023.

Pseudomyxoma peritonei (PMP) is a rare neoplastic condition characterised by gelatinous ascites, which generally arise from mucin-producing appendiceal tumours. Presentation is variable but requires prompt recognition to ensure appropriate specialist management due to risk of malignancy.A male in his 40s presented with a 1-day history of sudden onset, non-migratory abdominal pain, worse in the right iliac fossa. He had no significant medical history nor known drug allergies. Examination revealed right iliac fossa peritonism and blood tests revealed raised inflammatory markers. CT scan showed a right-sided abdominal collection. Intraoperatively, a diagnostic laparoscopy was performed, which revealed extensive mucin in the abdominal cavity. This was washed out and a laparoscopic appendectomy was performed; histopathology confirmed PMP from the ruptured appendix.

Pseudomyxoma peritonei (PMP) is an unusual clinical condition typically presenting with widespread mucinous neoplastic lesions within the peritoneum resulting in gelatin material-rich ascites. It was first described by Werth in 1884. Ever since, its clinical presentation, definition, site of origin, and prognosis have been a subject of debate. However, many histopathologic, immunohistochemical, and genetic studies have attempted to locate the primary lesion in the appendix in both genders.

To analyze the histological origin and survival outcomes of pseudomyxoma peritonei in patients treated at a regional cancer center.

Fifteen cases of PMP were diagnosed during the five-year study period. The demographic and clinicopathological details were retrieved; the slides were reviewed and histological parameters reassessed. Descriptive statistics were used to express proportions. Continuous variables were recorded as mean (SD) or median (IQR). Kaplan-Meier (KM) curve was used to estimate overall survival.

Mean age for PMP was found to be 47.5 years for low grade Mucinous Carcinoma Peritonei (MCP), 54.2 years for high grade MCP, and 58 years for high grade MCP with signet ring cells. Most common overall presentation was abdominal distension in 53.3% (8/15) of cases, followed by acute appendicitis in 20% (3/15) cases. PMP was detected synchronous with the primary tumor in 9/15 cases (60%). Primary lesion in the appendix was grossly identified in 7/15 cases, while it was not explored in the remaining eight cases. Yet, by combined clinical, radiological, histopathological, and immunohistochemical analysis, we identified that most of the cases (14/15) had an appendiceal origin (93.3%). The overall survival for 12 months was 50% and for 18 months was 37%.

The surgeon and radiologist may well bear in mind the most common possibility of an appendiceal origin for PMP and resect the appendix, irrespective of the presence of a grossly or radiologically detectable lesions. We emphasize that immunohistochemistry helped to detect the site of origin even when the primary was occult.

Pseudomyxoma peritonei (PMP) is characterized by the accumulation of mucinous fluid in the abdominal cavity, typically originating from mucin-producing tumors, most commonly arising in the appendix.

A 63-year-old male patient presented to the hospital with complaints of abdominal pain, significant weight loss, a palpable mass in the right iliac fossa, and evidence of ascites. A diagnosis of PMP was proposed based on findings from a computed tomography (CT) scan, which was subsequently confirmed through histopathological examination of a biopsy. The patient underwent successful treatment with Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy (CRS-HIPEC).

Diagnosing PMP presents challenges due to its rarity and the potential for extensive spread throughout the peritoneal cavity, necessitating a multidisciplinary approach for successful treatment.

Pseudomyxoma peritonei is a rare yet medically significant condition. Documenting a case of this ailment in Palestine has the potential to advance medical understanding, raise awareness, and improve patient care standards within the local healthcare system. By documenting this uncommon condition, healthcare practitioners in Palestine can gain valuable insights into its manifestations, diagnostic processes, and treatment modalities. This contribution not only enriches the global medical literature but also promotes collaboration in addressing the challenges associated with rare diseases.

Although pseudomyxoma peritonei (PMP) classically presents with profuse mucinous ascites within the peritoneal cavity, the physical manifestations of this disease exist on a spectrum, with the possibility of milder forms that lack typical findings. The authors report an indolent case of PMP diagnosed incidentally during workup and treatment for chronic cholecystitis in a 43-year-old male. This presentation of PMP was atypical due to a lack of discernible symptoms as well as uncharacteristic intraoperative findings consisting of numerous omental and pelvic adhesions with only sparse mucinous deposits. This case contributes to the growing understanding of PMP by exploring an uncharacteristic presentation of the disease with the hope that it may assist clinicians in diagnosing those cases of PMP that are more indolent and insidious in nature.

Careful macroscopic assessment of surgical scars is needed to avoid routine scar resection during cytoreductive surgery (CRS) for peritoneal metastases (PM). This study aimed to analyze the correlation between macroscopically suspected and microscopically confirmed scar metastases (SMs), and to analyze the prognostic impact of not undergoing routine scar resection.

All patients with previous surgery, treated with CRS and hyperthermic intraperitoneal chemotherapy, for colorectal PM or pseudomyxoma peritonei (PMP), at Uppsala University Hospital in 2013-2021, were included. Macroscopic SMs in surgical reports were compared with histopathological analyses.

In total, 227 patients were included. Among colorectal PM patients (n = 156), SM was macroscopically suspected in 41 (26%) patients, and 63 (40%) underwent scar resection. SM was confirmed in 19 (30%). Among patients with macroscopic suspicion, 45% had confirmed SM (positive predictive value, PPV). A total of 1 of 23 (4%) patients with no macroscopic suspicion had SM (negative predictive value, NPV = 96%). Among the PMP patients (n = 71), SM was macroscopically suspected in 13 (18%), and 28 (39%) underwent scar resection, of whom 12 (43%) had SM. The PPV was 77%. Occult SM was found in 1 of 14 (NPV = 93%). Not undergoing routine scar resection did not affect recurrence-free survival (RFS, p = 0.2) or overall survival (OS, p = 0.1) in colorectal PM patients or PMP patients (RFS p = 0.7, OS p = 0.7).

Occult SM is uncommon and scar resection does not affect RFS or OS. Therefore, macroscopically benign-appearing scars can be left without resection, though resection should be performed upon suspicion or uncertainty.

Pseudomyxoma peritonei (PMP) is a rare and complex clinical syndrome characterized by the accumulation of mucinous ascites within the peritoneal cavity, typically associated with mucinous tumours of appendiceal origin. Despite its rarity, PMP poses significant challenges in diagnosis and management due to its indolent yet locally aggressive nature. This comprehensive review provides insights into the diagnosis, management, and prognosis of PMP, synthesizing current evidence and emerging trends in the field. Challenges and opportunities in PMP management are discussed, along with recommendations for clinical practice emphasizing the importance of a multidisciplinary approach and specialized care. Despite ongoing challenges, advances in surgical techniques, perioperative chemotherapy, and emerging therapies offer hope for improved outcomes and quality of life for PMP patients.

Appendiceal mucinous neoplasms (AMNs) are uncommon gastrointestinal tumors characterized by mucus accumulation in the appendix. Patients may complain of acute appendicitis-like symptoms with other alarming features, but approximately half of the cases of AMNs are found incidentally on imaging. Early diagnosis and management of these neoplasms are important to prevent malignant progression and complications such as bowel obstruction and pseudomyxoma peritonei. We report a case of a 28-year-old female who initially presented with vomiting and acute left lower abdominal pain radiating to the left flank. Computed tomography (CT) revealed a 1.5 mm stone in the left ureteral vesicular junction and a 2.3 x 2.4 x 5.2 cm cystic tubular mass at the base of the cecum, suspicious of an appendiceal mucocele. An elective laparoscopic appendectomy was performed on this admission, which was converted to a right hemicolectomy due to the pathologic finding of a focally high-grade AMN on intraoperative frozen specimen pathology. This report aims to provide an example of a case of an incidental AMN and how it was diagnosed and managed surgically. AMNs are rare tumors that originate from the appendix and can pose diagnostic and therapeutic challenges due to their diverse clinical presentations and variable histopathological features. The majority of cases of AMNs are discovered in middle-aged individuals (40-50 years of age) after an appendectomy is performed and examined by pathology. This case report aims to describe a rare presentation of a 28-year-old female patient with an incidental finding of AMN on a CT scan of the abdomen while being worked up for suspected nephrolithiasis. We will provide a comprehensive overview of a unique presentation of AMN, highlighting its clinical manifestations, diagnostic approach, and management strategies. We present the case of a 28-year-old female patient who presented to the emergency department with complaints of acute left lower quadrant abdominal pain radiating to the left flank and vomiting. After an initial assessment and workup, which included lab investigations and imaging, a diagnosis of unilateral hydronephrosis due to a calculus of the ureterovesical junction was made. However, there was also suspicion of an appendiceal mucocele, as evidenced by a CT scan of the abdomen and pelvis. On admission day one, under the care and management of the urology team, she passed the stone with complete resolution of the presenting symptoms. On hospital day two, she underwent an elective laparoscopic appendectomy followed by a right hemicolectomy due to findings of high-grade mucinous neoplasm on the resected frozen specimen near the base of the appendix. AMN was an incidental finding based on CT imaging and macroscopic findings, which was later confirmed by histopathological assessment and report.

Pseudomyxoma peritonei (PMP) is a rare disease characterized by extensive peritoneal implantation and mass secretion of mucus after primary mucinous tumors of the appendix or other organ ruptures. Cytoreductive surgery (CRS) combined with hyperthermic intraperitoneal chemotherapy (HIPEC) is currently the preferred treatment, with excellent efficacy and safety, and is associated with breakthrough progress in long-term disease control and prolonged survival. However, the high recurrence rate of PMP is the key challenge in its treatment, which limits the clinical application of multiple rounds of CRS-HIPEC and does not benefit from conventional systemic chemotherapy. Therefore, the development of alternative therapies for patients with refractory or relapsing PMP is critical. The literature related to PMP research progress and treatment was searched in the Web of Science, PubMed, and Google Scholar databases, and a literature review was conducted. The overview of the biological research, treatment status, potential therapeutic strategies, current research limitations, and future directions associated with PMP are presented, focuses on CRS-HIPEC therapy and alternative or combination therapy strategies, and emphasizes the clinical transformation prospects of potential therapeutic strategies such as mucolytic agents and targeted therapy. It provides a theoretical reference for the treatment of PMP and the main directions for future research.

Pseudomyxoma peritonei (PMP) was a complex disease that had attracted increasing attention. However, there had been no bibliometric analysis of this disease so far. This study aimed to explore the current situation and frontier trend of PMP through bibliometric and visualization analysis, and to indicate new directions for future research.

The original research articles and reviews related to the PMP research were downloaded from Web of Science Core Collection on September 11, 2023. CiteSpace (6.2.R4) and VOSviewer(1.6.18) were used to perform bibliometric analysis of the publications, and establish the knowledge map. The data collected was analyzed using the Online Analysis Platform of Bibliometric to evaluate the cooperation of countries in this field.

We identified 1449 original articles and reviews on PMP published between 1998 and 2023. The number of publications on PMP increased continuously. The United States, the United Kingdom and China were the top contributors. The most productive organization was the MedStar Washington Hospital Center. Sugarbaker, Paul H. was the most prolific author and the most cited. Keyword analysis showed that "Pseudomyxoma peritonei", "cancer", "cytoreductive surgery", and "hyperthermic intraperitoneal chemotherapy" were the most common keywords. The earliest and latest used keywords were "mucinous tumors" and "impact", respectively. "classification", "cytoreductive surgery", "appendiceal" were the top 3 strongest citation bursts. The reference "Carr NJ, 2016, AM J SURG PATHOL" had the highest co-citations.

This bibliometric analysis showed an increasing trend in literature related to PMP. The research trends and hotspots identified in this study could guide the future research directions in this field, in order to promote the development of PMP.

Pseudomyxoma peritonei (PMP) of pancreatic origin arising from an intraductal papillary mucinous neoplasm (IPMN) is rare. Cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC) has been established as the optimal treatment for PMP. However, the benefits and safety of CRS with HIPEC for treating PMP of pancreatic origin remain unclear. Herein, we describe a case of PMP of pancreatic origin that was treated with CRS and HIPEC without postoperative complications. A 75-year-old woman was referred to our department. Computed tomography (CT) revealed a multilocular cystic tumor in the pancreatic tail, notable mucinous ascites in the abdominal cavity, and scalloping of the liver and spleen. CT did not reveal the appendix, and the ovaries were normal in size. The patient was diagnosed with PMP of pancreatic origin, and CRS and HIPEC were performed. Intraoperatively, the pancreatic tumor was perforated, and there was a large amount of mucinous ascites. We performed distal pancreatectomy in addition to CRS and HIPEC, with no intraoperative complications. The postoperative course was uneventful, and the patient survived after 6 months without recurrence. CRS with HIPEC may be a feasible treatment option for PMP of pancreatic origin.

The peritoneal cancer index (PCI) has been used to predict surgical outcomes for pseudomyxoma peritonei (PMP). The present study aimed to establish the optimal cutoff point for PCI to predict surgical resectability of PMP.

A total of 366 PMP patients were included. The patients were divided into low-grade and high-grade groups. Based on the completeness of the cytoreduction (CC) score, both low-grade and high-grade PMP patients were further divided into complete cytoreductive surgery (CRS) and maximal tumor debulking (MTD) subgroups. The ability to predict surgical resectability of total and selected PCI (regions 2 + 9 to 12) was analyzed through receiver operating characteristic (ROC) curves.

Both total and selected PCI demonstrated excellent discriminative ability in predicting surgical resectability for low-grade PMP patients (n = 266), with the ROC-AUC of 0.940 (95% CI: 0.904-0.965) and 0.927 (95% CI: 0.889-0.955). The corresponding optimal cutoff point was 21 and 5, respectively. For high-grade PMP patients (n = 100), both total and selected PCI exhibited good performance in predicting surgical resectability, with the ROC-AUC of 0.894 (95% CI: 0.816-0.946) and 0.888 (95% CI: 0.810-0.943); correspondingly, the optimal cutoff point was 25 and 8, respectively. The discriminative ability between total and selected PCI in predicting surgical resectability did not show a statistical difference.

Both total and selected PCI exhibited good performance and similarity in predicting complete surgical resection for both low-grade and high-grade PMP patients. However, the selected PCI was simpler and time-saving in clinical practice. In the future, new imaging techniques or predictive models may be developed to better predict PCI preoperatively, which might assist in confirming whether complete surgical resection can be achieved.

Low-grade appendiceal mucinous neoplasms (LAMN) are very rare, accounting for approximately 0.2%-0.5% of gastrointestinal tumors. We conducted a multicenter retrospective study to explore the impact of different surgical procedures combined with HIPEC on the short-term outcomes and long-term survival of patients.

We retrospectively analyzed the clinicopathological data of 91 LAMN perforation patients from 9 teaching hospitals over a 10-year period, and divided them into HIPEC group and non-HIPEC group based on whether or not underwent HIPEC.

Of the 91 patients with LAMN, 52 were in the HIPEC group and 39 in the non-HIPEC group. The Kaplan-Meier method predicted that 52 patients in the HIPEC group had 5- and 10-year overall survival rates of 82.7% and 76.9%, respectively, compared with predicted survival rates of 51.3% and 46.2% for the 39 patients in the non-HIPEC group, with a statistically significant difference between the two groups (χ2 = 10.622, p = 0.001; χ2 = 10.995, p = 0.001). Compared to the 5-year and 10-year relapse-free survival rates of 75.0% and 65.4% in the HIPEC group, respectively, the 5-year and 10-year relapse-free survival rates of 48.7% and 46.2% in the non-HIPEC group were significant different between the two outcomes (χ2 = 8.063, p = 0.005; χ2 = 6.775, p = 0.009). The incidence of postoperative electrolyte disturbances and hypoalbuminemia was significantly higher in the HIPEC group than in the non-HIPEC group (p = 0.023; p = 0.044).

This study shows that surgery combined with HIPEC can significantly improve 5-year and 10-year overall survival rates and relapse-free survival rates of LAMN perforation patients, without affecting their short-term clinical outcomes.

Peritoneal cancer index (PCI) is the surgical variable most commonly used to quantify the extent of peritoneal metastases for pseudomyxoma peritonei (PMP) patients. The present study aimed to investigate the agreement between CT predicted and surgical PCI by the Bland-Altman method for PMP of appendiceal origin. A total of 167 PMP patients of appendiceal origin were included between 2016 and 2021. Bland-Altman analysis was performed for both total PCI and selected PCI (regions 2 + 9-12). After the Bland-Altman plot was drawn, the mean bias and its 95% limit of agreements (LoAs) was quantified. Besides, the correlation coefficients between CT-PCI and surgical PCI were also been calculated. The Bland-Altman plot showed the mean bias ± SD between total CT-PCI and surgical PCI as 0.431 ± 3.005, with the LoAs from - 5.459 to 6.321. There were nine points of difference in total PCI exceeded the 95% LoAs, with the rate of 5.39% (9/167). As for selected CT-PCI, Bland-Altman plot showed the mean bias ± SD between selected CT-PCI and surgical PCI as - 0.287 ± 1.955, with the LoAs from - 4.118 to 3.544. There were ten points of difference in selected PCI exceeded the 95% LoAs, with the rate of 5.99% (10/167). The Spearman's rank correlation coefficient between total CT-PCI and surgical PCI was 0.911, P < 0.001, as for selected CT-PCI and surgical PCI, the coefficient was 0.909, P < 0.001. Although there was a strong correlation for both total and selected CT-PCI with surgical PCI, however, the agreement is still not good in Bland-Altman analysis, which suggested that CT-PCI cannot predict surgical PCI accurately even in professional PMP treatment centers. In brief explanation, CT makes it difficult to distinguish the borderline between tumor tissue and mucus and to detect tumor lesions in the small intestine regions, which caused overestimation or underestimation by CT-PCI. In the future, a multiple linear regression model based on CT-PCI might accurately predict surgical PCI preoperatively.

Patients with low-grade appendiceal mucinous carcinomas (LAMNs) treated with cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) have a favorable prognosis. However, a subgroup of patients presents a clinically aggressive course with disease progression despite receiving treatment. The purpose of this study is to report the experience of clinically aggressive LAMN patients treated by the same team, and to present a review of the literature. The cases of four patients with clinically aggressive LAMNs were reviewed. Clinical and histopathological characteristics were re-examined. Recurrences and the time of recurrence, as well as the survival time, were recorded. These patients were four men with clinically aggressive LAMNs treated with CRS plus HIPEC. One of them underwent CC-0 surgery, two underwent CC-1 surgery, and one underwent CC-3 surgery. All patients received systemic chemotherapy after surgery. Recurrence was recorded in three of the patients within 4-23 months after the initial treatment. Two of the patients underwent secondary CRS. Three patients died of disease recurrence within 13-23 months, and one is alive with a disease relapse at 49 months after his initial surgery. LAMNs were identified in both the initial specimens and the specimens obtained during reoperation. The prognosis of LAMN patients treated with CRS plus HIPEC is favorable. A small number of patients present a clinically aggressive course that is unresponsive to any treatment. Molecular and genetic studies are required to identify this group of LAMN patients who have an unfavorable prognosis.

Optimal management of pseudomyxoma peritonei (PMP) is by cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC), which can achieve 20-year disease-free, and overall survival. There is limited information on the health-related quality of life (HRQOL) of PMP survivors beyond five years. We report longitudinal HRQOL in patients with PMP of appendiceal origin up to 17-years after their CRS and HIPEC in 2003-2004.

Patients had HRQOL assessed with EORTC QLQ-C30 questionnaires pre-operatively, and at 1-, 10- and 17-years post-operatively. Comparisons in global health-related QOL (global-HRQOL) measures were made with (1) an age- and sex-matched normal European population, (2) between patients who underwent complete cytoreduction (CRS CC0/1) versus maximal tumor debulking (MTD), and (3) between those with and without peritoneal recurrence.

Forty-six patients underwent CRS & HIPEC for appendiceal PMP. One patient withdrew from the study. Of the 45 patients, 23 patients were alive at ten and 15 patients at 17-years post-operatively. 21/23 (91%) and 14/15 patients (93%) completed questionnaires respectively. Pre-operatively, patients had significantly lower global-HRQOL compared with the reference population. Over follow-up, patients experienced improvements in their global-HRQOL. By post-operative year-10 and -17, there was no difference between the global-HRQOL of patients and reference population. As expected, patients with CC0/1 and without peritoneal tumor recurrence had better global-HRQOL at ten- and 17-years post-operatively compared with those with MTD or recurrence.

Optimal CRS and HIPEC is an effective treatment for appendiceal PMP that can achieve long-term survival. HRQOL is excellent and maintained, in those who have CC0/1 without recurrence.

As the standard treatment for pseudomyxoma peritonei (PMP), cytoreductive surgery (CRS) plus hyperthermic intraperitoneal chemotherapy (HIPEC) can significantly prolong the survival of PMP patients, and some patients can even achieve long-term survival (LTS) or clinical cure. The purpose of this study was to analyze the clinicopathological and treatment features of PMP patients with LTS and to explore the survival benefit factors of PMP patients.

The clinicopathological and prognostic data of PMP patients who received CRS + HIPEC at our center from December 2004 to May 2023 were retrospectively analyzed. PMP patients were divided into LTS group (≥ 10 years) and short-term survival (STS) group (< 5 years) according to the length of natural history. Univariate and multivariate analyses were performed to explore the beneficial factors of PMP patients with LTS.

A total of 609 patients with PMP received CRS + HIPEC treatment at our center. Two-hundred one patients with PMP were included in the study after screening, including 39 patients (19.4%) in the LTS group and 162 patients (80.6%) in the STS group. In STS group and LTS group, median overall survival based on natural history was 29.2 (2.4-59.9) vs. 138.9 (120.3-416.7) months. Univariate analysis revealed 8 factors (P < 0.05) with statistically significant differences between the two groups: gender, chemotherapy history, previous surgical score, Karnofsky Performance Status score, pathological diagnosis, lymphatic metastasis, peritoneal cancer index, and completeness of cytoreduction (CC). Multivariate analysis identified only two factors independently associated with LTS of PMP patients: CC and pathological diagnosis.

Complete CRS and pathological features are two key factors affecting LTS in PMP patients.

Low-grade appendiceal mucinous neoplasms (LAMN) are rare and are diagnosed in at least 0.13% of appendectomies in Germany, although significant underreporting is likely. Perforation of the tumors can result in abdominal mucinous collections, so-called pseudomyxoma peritonei (PMP). The challenge in the treatment of LAMN is the adequate approach to the incidental finding of these tumors. If a mucinous neoplasm is preoperatively suspected in cases of an acute condition, usually appendicitis, it must be weighed up whether a conservative approach is justifiable or whether immediate appendectomy is necessary. If this is the case, an intraoperative perforation of the appendix must be avoided and the complete abdominal cavity must be inspected for mucin deposits. If conservative treatment is possible, further treatment should take place at a specialized center. If the neoplasm is first found incidentally during surgery, perforation of the appendix should also be avoided and the entire abdominal cavity should be inspected for a PMP. If a PMP is present cytoreduction and hyperthermic intraperitoneal chemotherapy (HIPEC) should be performed in a specialized center. If LAMN are found during the postoperative histological work-up, it should be evaluated whether a perforation was present and mucin collections are noted in the surgical report. In the case of LAMN without evidence of a PMP, appendectomy is the adequate treatment. In cases of intra-abdominal mucinous collections, samples should be taken and further treatment should be performed at a center with sufficient expertise. An ileocecal resection or oncological hemicolectomy is not indicated. After adequate treatment, all patients should receive a follow-up using cross-sectional imaging (preferably magnetic resonance imaging, MRI) and determination of the tumor markers CEA, CA 19-9 and CA 125.

Cytoreductive surgery (CRS) plus hyperthermic intraperitoneal chemotherapy (HIPEC) is the standard treatment for pseudomyxoma peritonei (PMP). It can significantly prolong the survival of patients, but at the same time may increase the risk of postoperative infection.

Patients with PMP who underwent CRS + HIPEC at our center were retrospectively analyzed. According to PMP patients, basic clinical data and relevant information of postoperative infection, we analyzed the common sites of postoperative infection, results of microbial culture and the antibiotics sensitivity. Univariate and multivariate analysis were performed to explore infection-related risk factors.

Among the 482 patients with PMP, 82 (17.0%) patients were infected after CRS + HIPEC. The most common postoperative infection was central venous catheter (CVC) infection (8.1%), followed by abdominal-pelvic infection (5.2%). There were 29 kinds of microbes isolated from the culture (the most common was Staphylococcus epidermidis), including 13 kinds of Gram-positive bacteria, 12 kinds of Gram-negative bacteria, and 4 kinds of funguses. All the antibiotics sensitivity results showed that the most sensitive antibiotics were vancomycin to Gram-positive bacteria (98.4%), levofloxacin to Gram-negative bacteria (68.5%), and fluconazole to fungus (83.3%). Univariate and multivariate analysis revealed the infection independent risk factors as follow: intraoperative blood loss ≥ 350 mL (P = 0.019), ascites volume ≥ 300 mL (P = 0.008).

PMP patients may have increased infection risk after CRS + HIPEC, especially CVC, abdominal-pelvic and pulmonary infections. The microbial spectrum and antibiotics sensitivity results could help clinicians to take prompt prophylactic and therapeutic approaches against postoperative infection for PMP patients.

A patient survey highlighted that patients treated with cytoreductive surgery (CRS) combined with hyperthermic intraperitoneal chemotherapy (HIPEC) at one NHS trust lacked confidence with the transition of care between teams. A personalised folder of treatment information was designed and given to patients prior to discharge.

To obtain patient feedback on the implementation and content of the folder.

30 consecutive patients were given the folder at discharge. Participants completed an online questionnaire to determine whether the information in the folder was appropriate, given at the right time in the pathway and enhanced confidence on discharge.

90% response rate was achieved. Of the respondents, 96% strongly agreed/agreed that the folder was helpful, 4% disagreed; 92% strongly agreed/agreed that the amount of information was right, 8% preferred more information, none less; 74% agreed/strongly agreed that the folder was provided at the right time; 96% said that the content met their expectations.

Patients treated with CRS and HIPEC have specific needs related to their treatment. Implementation of the patient information folder at discharge increases patient confidence.

Pseudomyxoma peritonei (PMP) is a rare malignant disease. Adding of the Ki67 proliferation index to the PSOGI PMP classification provided two different subcategories of the extensive HG-PMP group (HG-PMP ≤15% and HG-PMP >15%) with different survival in a previous unicentric study. This study aims to carry out an external and multicentre validation of this new proposed classification.

It was a prospective analysis of samples from a historical and international cohort of patients. A representative area with higher cellular density was used to determine the Ki67%. The Ki67 proliferation index (%) was determined in all the HG-PMP patients. A Cox proportional hazard models and multivariable COX models were used. The Kaplan-Meier method and the two-tailed log-rank test were used to analyse the effect of different PSOGI-Ki67 categories on OS and DFS. Its predictive accuracy was analysed using Harrel's C-index and the ROC curve. The calibration was performed using the calibration plots matching.

After exclusions, 349 patients were available for analysis. The 5-years OS were 86% for LG-PMP, 59% for HG-PMP≤15, 38% for HG-PMP>15 and 42% for SRC-PMP (p = 0.0001). The 5-years DFS were 49% for LG-PMP, 35% for HG-PMP≤15, 16% for HG-PMP>15 and 18% SRC-PMP (p = 0.0001). The discrimination capability of PSOGI-Ki67 was validated.

the PSOGI-Ki67 classification discriminates and predicts the OS and DFS in patients with PMP dividing the HG-PMP category into two well-defined sub-categories. The Ki67 proliferation index should be incorporated routinely in the pathology report for these patients.