Colitis cystica profunda diagnosed by laparoscopic excision: A case report and review of literature

Abstract

BACKGROUND

Colitis cystica profunda (CCP) is a rare condition with multiple cystic lesions in the mucosal/submucosal layers, predominantly involving the rectum and sigmoid colon. Its etiology remains unclear, with mucinous neoplasms and polyps as major differential diagnoses. Nonspecific imaging and clinical manifestations make preoperative diagnosis challenging (most confirmed postoperatively). This report summarizes reported cases, adds a new one, and compares it with 106 prior cases to enhance understanding of its features, diagnosis and management.

CASE SUMMARY

Herein, we report a 32-year-old man with a history of colonoscopy detection of two submucosal colonic elevations (20 cm and 18 cm from the anal verge) 2 weeks ago, without any disturbing symptoms. Endorectal ultrasound showed two cystic masses in the sigmoid’s intrinsic muscular and submucosal layers. Computed tomography showed rectosigmoid thickening. We performed a laparoscopic operation to remove the lump. Final pathology was diagnosed with CCP. The patient was discharged five days later and had follow-up visits with no signs of relapse for a period of 3 months.

CONCLUSION

CCP is rare and the clinical symptoms are not typical, and pre-operative diagnosis is difficult. Histopathology is required for definitive diagnosis. Surgical excision is widely reported as the surgical treatment of choice for CCP.

Key Words: Colitis profunda; Colitis cystica profunda; Hyperplastic cystic lesion; Submucosal cysts of the colon; Heterotopic submucosal colon; Case report

Core Tip: Colitis cystica profunda is a rare, benign but easily misdiagnosed cystic mucin-filled lesion that favors the recto-sigmoid wall, may be clinically silent or masquerade as mucinous neoplasm, and can only be confidently distinguished from malignancy by histopathologic examination of the fully excised specimen, so complete surgical removal and thorough pathologic assessment remain the cornerstone of management.

INTRODUCTION

Colitis cystica profunda (CCP) is an uncommon benign condition of the colon and rectum that can be mistaken for suspicious polyps, mucinous adenocarcinomas, or carcinoid tumors, with few cases reported in the literature[1]. Stark first documented submucosal cysts in the colon in 1766 while performing autopsies on two patients suffering from chronic dysentery. Virchow introduced the term colitis cystica polyposa to describe multiple polypoid cystic submucosal lesions 1863. Goodall and Sinclair changed the name to CCP and finalized the terminology in 1957[2]. Its etiology is not entirely clear, with many experts suggesting inflammatory, ischemic, and post-traumatic processes as contributing factors[3]. CCP is an uncommon benign lesion occurring in the rectum or colon, most commonly located in the anterior rectal wall. Its key pathological trait lies in mucus-filled cysts that extend into the submucosa, muscular layer, or even the serous layer. These cysts contain substantial amounts of mucus and lack the hallmarks of malignant neoplasms[4]. Few case reports on ultrasonography of CCP have been previously published in the literature.

We conducted a literature search of case reports of CCP published from 1955 to 2025. The keywords searched included “colitis cystica profunda”, “submucosal cysts of the colon”, and “heterotopic submucosal colon glands”. We also reported a retrospective case from our group and compared it with cases from the existing literature.

CASE PRESENTATION

Chief complaints

A 32-year-old man presented for consultation with a history of colonoscopy detection of two submucosal colonic elevations (20 cm and 18 cm from the anal verge) 2 weeks ago (Figure 1) without any disturbing symptoms.

Figure 1 Colonoscopy. A: Large submucosal mass 18 cm from the anal verge; B: Large submucosal mass 20 cm from the anal verge.

History of present illness

The patient reported no specific complaints or discomfort.

History of past illness

The patient denies a history of diabetes mellitus, tuberculosis, typhoid fever, malaria, heart disease, cerebrovascular disease, or mental illness. No history of trauma or surgery. Denies any food or drug allergies.

Personal and family history

The patient denied any family history of malignant tumors.

Physical examination

Physical examination revealed stable vital signs, with a blood pressure of 126/69 mmHg, and pulse of 65/minute and no abnormal findings on abdominal and cardiac examination.

Laboratory examinations

Levels of serum tumor (carbohydrate antigen 72-4, carbohydrate antigen 199, carcinoembryonic antigen) markers were normal. Other blood tests revealed no abnormalities.

Imaging examinations

Colonoscopy revealed two large submucosal mass 20 cm and 18 cm from the anal verge (Figure 1). Endorectal ultrasound revealed two cystic mass was observed at the 20 o'clock direction in the left lateral position, in the intrinsic muscular layer and submucosal layer of the sigmoid, with a size of 23.0 mm × 12.6 mm and 21.3 mm × 15.2 mm in diameter, regular morphology, clear boundary, protruding into the lumen, with poor internal transmission and heterogeneous echogenicity or anechoic echogenicity (Figure 2). No abnormalities were found in the physical exam of the patient, and his laboratory tests, such as routine blood work and tumor markers, were within normal limits. Computed tomography (CT) scan of the abdomen displayed an irregular focal thickening of the rectosigmoid wall, with mild to moderate enhancement (Figure 3).

Figure 2 Endoscopic ultrasonography. A: A cystic mass 20 cm from the anal verger in the intrinsic muscular layer, with a size of 23.0 mm × 12.6 mm, clear boundary, regular morphology, protruding into the lumen, with poor internal transmission and heterogeneous echogenicity; B: A cystic mass 18 cm from the anal verger in the submucosal layer, with a size of 21.3 mm × 15.2 mm, clear boundary, regular morphology, protruding into the lumen, with anechoic echogenicity.

Figure 3 Contrast-enhanced computed tomography. A: Uneven-density foci on the plain scan, with smooth rectal mucosa and intact intestinal wall; B: Inhomogeneous enhancement is seen in the enhancement phases of the lesion.

FINAL DIAGNOSIS

The patient was diagnosed with CCP.

TREATMENT

We suspected gastrointestinal stromal tumor. In conjunction with the patient willingness, we performed a laparoscopic operation to remove the lump. Pathological examination showed no abnormalities in the mucosa. The mass 20 cm from the anal was appeared soft and grayish-white, and showed obvious jelly-like changes, measured 2.5 cm × 2 cm × 1.7 cm. The pathological manifestations of the mass 18 cm from the anal was similar with the mass 20 cm from the anal, measured 2.5 cm × 1.8 cm × 1.5 cm (Figure 4A).

Figure 4 Macroscopic examination and histopathological imaging of the specimen. A: The resected bowel specimen; B: Histopathological analysis of the resected specimen (hematoxylin × 40); C: The resected appendix; D: Simple appendicitis.

Intraoperative frozen-section pathology suggested low-grade mucinous neoplasms (Figure 4B). However, the low-grade mucinous neoplasms in most cases are from mucinous tumors arising from the appendix. Subsequently, communication was made with the family of the patient and the patient underwent an appendectomy (Figure 4C). The results were described as simple appendicitis (Figure 4D). This result differs from the one we imagined. Finally, the conclusion was reached after discussion by the pathologists. This is not low-grade mucinous neoplasms. At the micro level, mucous cells infiltrated the muscularis propria, covered by epithelium without cellular atypia, these cells extend beneath the muscularis mucosa and infiltrate the colonic muscularis propria. Ultimately, the patient was diagnosed with CCP.

OUTCOME AND FOLLOW-UP

The patient was discharged five days later and had follow-up visits with no signs of relapse for a period of 3 months.

DISCUSSION

Up to now, there have been 106 documented cases of CCP, not counting the one mentioned in this report. The clinical and treatment details for these cases are outlined in Table 1. In total, 106 cases were identified, including 66 men (62.3%) and 40 women (37.7%), with a male-to-female ratio of 1.65. The mean age of the patients was 39.1 (range, 5-82) years old. Among the cases, 57.5% (n = 61) of lesions were located in the rectum, 32.1% (n = 34) of lesions were located in the colon, one case of lesions was located in the junction of the rectum and sigmoid colon, 2.8% (n = 3) of lesions were located in the small intestine. The location of 2 cases was not described. In 5 patients, multiple lesions were in colon rectum and small intestine. Of the patients, 52% (n = 26) had previously received abdominal surgery. The main manifestations of CCP included mucus and bloody stool, abdominal pain, diarrhea and tenesmus. Of the 106 cases, only 7 were diagnosed before the surgical procedure, and the others were diagnosed through histopathologic examination after surgery.

Table 1 All published cases of gastritis cystica profunda from 1966-2025.

Ref.	Age	Sex	Lesion location	History of stomach surgery	Symptoms	Treatment
Epstein et al[11], 1966	55	Female	Rectum	No	Hemafecia	Excision
Grant and Roller[12], 1967	23	Female	Rectum	No	Hemafecia	Conservative
Sullivan et al[13], 1968	19	Male	Rectum	No	Diarrhea, mucous stool, emaciation	Excision
Sullivan et al[13], 1968	23	Male	Rectum	No	Diarrhea	Excision
Scruggs and Duckworth[14], 1968	31	Female	Rectum	No	Rectal pain, hemafecia, tenesmus, hemorrhoids, mucopurulent bloody stool	Conservative
Scruggs and Duckworth[14], 1968	15	Female	Rectum	No	Abdominal pain, tenesmus, diarrhea, mucopurulent bloody stool	Excision
Fechner[15], 1967	62	Male	Colon	Laparotomy, colotomy, a segmental resection	Hemafecia	Excision
Barner[16], 1967	36	Male	Colon transversum	No	Diarrhea, hemafecia, emaciation	Transverse colectomy, a double colostomy
Stolar and Silver[17], 1969	49	Female	Rectum	Fistulotomy, biopsy	Mucopurulent bloody stool	Abdominoperineal resection
Ghani[18], 1970	31	Male	Rectum	No	Mucopurulent bloody stool	Excision
Clark and Muldoon[19], 1970	60	Female	Sigmoid colon	No	Diarrhea, hemafecia	Colotomy, transcolonic polypectomy
Burt et al[20], 1970	76	Female	Sigmoid colon	Sigmoidoscopy, double mastoidectomy and hysteroscopy	Abdominal pain, mucopurulent bloody stool	The transverse colon with end-to-end anastomosis
O'Brien et al[21], 1971	65	Male	Sigmoid colon	No	Mucopurulent bloody stool	A segmental resection of the sigmoid colon
Talerman[22], 1971	25	Male	Rectum	No	Mucopurulent bloody stool	Excision
Ballas et al[23], 1971	27	Male	Rectum	No	No symptoms	Excision
Young et al[24], 1972	17	Male	Rectum	History of anal fissure surgery	Abdominal pain, hemafecia	Extensive local resection
Herman and Nabseth[25], 1973	36	Male	Rectum	Cholecystectomy, appendectomy	Diarrhea, tenesmus	Colostomy
Green et al[26], 1974	25	Female	Rectum	Hemorrhoidectomy, perianal condyloma acuminatum	Mucopurulent bloody stool, tenesmus	Excision
Farman et al[27], 1974	70	Female	Sigmoid	Cholecystectomy	No symptoms	Laparotomy
Farman et al[27], 1974	23	Male	Rectum	No	Rectal pain, hemafecia, diarrhea	Conservative
Farman et al[27], 1974	52	Female	Rectum	No	Recurrent ventral hernia	Conservative
Lasser and Acosta[28], 1975	37	Male	Sigmoid colon	Bilateral ureterosigmoidostomy	Confusion, weakness, lethargy, vomiting, metabolic acidosis	Partial colonic resection, ileal loop diversion
Friedman and Tueller[29], 1975	26	Male	Rectum	No	Watery diarrhea	Corticosteroid enemas
Tedesco et al[30], 1976	36	Male	Rectum	No	Mucopurulent bloody stool	Conservative
Tedesco et al[30], 1976	27	Female	Rectum	No	Diarrhea, mucopurulent bloody stool	Local excision
Tedesco et al[30], 1976	31	Female	Rectum	No	Diarrhea, rectal pruritus	Conservative
Tedesco et al[30], 1976	19	Male	Descending colon and sigmoid colon	No	Mucopurulent bloody stool (history of ulcerative colitis)	Total colectomy
Tedesco et al[30], 1976	60	Male	The junction of the descending and sigmoid colon	No	Diarrhea, abdominal pain	Endoscopic polypectomy, anterior colonic resection
Bhuta and Prathikanti[31], 1976	27	Male	Rectum	No	Hemafecia, tenesmus, abdominal pain, vomiting	Wide local excision
Rosen et al[32], 1976	37	Female	Colon	No	Abdominal gunshot wound	Colostomy
Nagasako et al[33], 1977	19	Male	Rectum	No	Mucopurulent bloody stool	Abdominoperineal resection
Kyriakos and Condon[34], 1978	48	Male	Ileum	Appendectomy side-to-side anastomosis of the jejune	Abdominal pain, abdominal distension, vomiting, diarrhea	Wedge resection of the jejunal segment
Baratz et al[35], 1978	57	Male	Ileum, The ileocecal junction, colon	Right nephrectomy, radiotherapy for clear cell renal cell carcinoma	Astriction	Right hemicolectomy, ileotransverse anastomosis
Ledesma-Medina et al[36], 1978	13	Female	Rectum	No	Type I rectal prolapse with bleeding	Excision
Shinohara et al[37], 1981	49	Male	Rectum	No	Diarrhea, astriction, rectal pain, anal bleeding	Perineal rectal resection
Magidson and Lewin[38], 1981	20	Male	Sigmoid colon	No	Mucopurulent bloody stool	Total proctocolectomy
Krummel et al[39], 1983	14	Male	Rectum	No	Anal pain, tenesmus, hemafecia	Excision
Suzuki and Matsumoto[40], 1983	14	Male	Rectum	No	Diarrhea, hemafecia	Extirpation of the polyp
Suzuki and Matsumoto[40], 1983	15	Female	Rectum	No	Mucopurulent bloody stool	Conservative
Nielsen et al[41], 1984	33	Male	No	No	Mucopurulent bloody stool (history of ulcerative colitis)	Conservative
Gardiner et al[42], 1984	55	Female	Colon	Radiotherapy for squamous carcinoma of the cervix (stage A), cholecystectomy	Bloody diarrhea, abdominal distension	Resection of the sigmoid colon with primary anastomosis, defunctioning transverse loop colostomy
Yashiro et al[43], 1985	70	Male	Sigmoid colon	No	Follow-up study	Polyp removal and surgery
Bentley et al[44], 1985	52	Male	Sigmoid colon	Decompression loop colostomy of the transverse colon, total colectomy + cecal sigmoid anastomosis	Abdominal pain, fever, hemafecia, mucoid loose stools, vomiting	Abdominal perineal resection, Koch ileostomy
Walker et al[45], 1986	36	Male	Rectum	Splenectomy	Abdominal pain, hemafecia, marasmus, mucoid loose stools	Rectal resection
Spjut et al[46], 1987	39	Male	Colon transversum jejunum	History of duodenal ulcer	Abdominal distension, rectal bleeding	Segmental resection of the transverse colon
Guy and Hall[47], 1988	17	Male	Rectum	No	Astriction, diarrhea, rectal bleeding, tenesmus	Mucosal sleeve resection
Hulsmans et al[48], 1991	48	Male	Rectum	No	No	Conservative
Kim et al[49], 1992	31	Male	Transverse colon	No	Hemafecia	Segmental resection with end-to-end anastomosis of the descending colon
Zidi et al[50], 1994	48	Female	Anterior wall of rectum, sigmoid transverse colon	Transabdominal rectopexy, diverting transverse colostomy	Hemafecia	Sigmoidectomy, low-sited colorectal anastomosis
Heusinkveld and Barnard[51], 1994	13	Male	Rectum	No	Hemafecia	Rectal resection
Lifshitz et al[52], 1994	37	Female	Rectum	No	Hemafecia	Transanal local excision
Valenzuela et al[53], 1996	30	Female	Rectum	No	Mucopurulent bloody stool	Conservative
Valenzuela et al[53], 1996	45	Male	Rectum	No	Abdominal pain, tenesmus, mucopurulent bloody stool	Conservative
Petritsch et al[54], 1996	30	Male		No	Mucopurulent bloody stool	EMR
Petritsch et al[54], 1996	27	Male	Rectum	No	Presented with rectal polyps for consultation	Conservative
Karnak et al[55], 1997	5	Male	100 cm distal to the ligament of Trietze and 120 cm proximal to the ileocecal valve	No	Abdominal pain, fever, biliary vomiting, ileal intussusception	Partial ileal segment resection and ileoileal anastomosis
Sakurai et al[56], 2000	53	Male	Colon transversum	No	Ulcerative colitis	Transverse colectomy
Wang et al[57], 2001	73	Male	Rectum	Spinal cord injury	Mucopurulent bloody stool	Transverse colostomy
Wang et al[57], 2001	47	Male	Rectum	Spinal cord injury	Mucopurulent bloody stool	Mesalamine enemas
Wang et al[57], 2001	75	Male	40 cm from the anal margin	Spinal cord injury	Irregular bowel movements, fecal incontinence	Left hemicolectomy and transverse colostomy
Madan and Minocha[58], 2002	37	Male	Sigmoid colon	Multiple sclerosis	Bloody diarrhea, abdominal pain, bile vomiting	Sigmoidectomy and end colostomy
Krüger et al[59], 2005	39	Female	Colon transversum	Crohn’s disease	Recurrent of bowel obstruction	Partial left hemicolectomy
Kayaçetin and Kayaçetin[60], 2005	18	Male	Rectum	No	Mucopurulent bloody stool, tenesmus, fatigue	Anterior resection with a protective colostomy, closure of the colostomy
Sarzo et al[61], 2005	No	Female	Rectum, sigmoid colon	No	Mucopurulent bloody stool	Anterior resection of the sigmoid colon and upper rectum
Dewandel et al[62], 2001	39	Female	Colon descendens	No	Abdominal pain, diarrhea	Excision
Inan et al[63], 2007	16	Male	Rectum	No	Mucopurulent bloody stool, tenesmus	EMR
Sztarkier et al[64], 2006	64	Female	Rectum	No	Hemafecia, ulcerative proctitis	Full-thickness transanal excision
Tajika et al[65], 2007	48	Male	Colon descendens	No	Positive fecal occult blood experiment	Right hemicolectomy
Kornprat et al[66], 2007	48	Female	Rectum	No	Astriction, rectal pain, rectal prolapse	Perineal proctectomy (altemeier procedure)
Laurent et al[67], 2007	66	Male	Rectum	Anorectal dysfunction resulting from a history of spinal surgery	Anal mass with prolapse, astriction, tenesmus	EMR
de Toro et al[68], 2007	35	Female	Sigmoid colon	Postoperative radiotherapy and chemotherapy for cervical cancer	Abdominal pain, vomiting	Proximal sigmoid colostomy
Dolar et al[69], 2007	44	Male	Rectum	No	Mucopurulent bloody stool tenesmus, rectal incontinence and prolapse	Low anterior resection with colon-anal anastomosis
Higuera Alvarez et al[70], 2008	50	Male	Ileum, sigmoid, colon transversum, caecum	No	Anorexia, weight loss, perianal abscess	Conservative
Toll and Palazzo[71], 2009	16	Male	Colon	No	Ulcerative colitis	Proctocolectomy
Fernández Salazar et al[72], 2009	70	Male	Sigmoid colon	No	Diarrhea, abdominal pain, weight loss, anemia, ulcerative colitis	Colectomy
Baltar-Arias et al[73], 2010	63	Female	Rectum	No	Mucopurulent bloody stool	Conservative
Jung et al[74], 2010	38	Male	Sigmoid	History of polypectomy of the colon	Hemafecia	EMR
Qayed et al[75], 2011	42	Male	Sigmoid colon	No	Abdominal pain, fever with chills, hemafecia, vomiting	Sigmoid colectomy and descending colostomy
Arana et al[76], 2014	49	Male	The junction of the rectum and sigmoid colon	No	Mucopurulent bloody stool, ulcerative colitis	Total proctosigmoidectomy with preservation of the anus and terminal ileostomy
Sultan et al[77], 2014	27	Male	Rectum	No	Hemafecia	Conservative
Cecinato et al[78], 2014	39	Male	Colon descendens	No	Colonoscopy follow-up (history of ulcerative colitis)	Segmental colectomy
Shin et al[79], 2014	65	Male	Sigmoid colon	No	Colonoscopy follow-up	EMR
Hernandez-Prera and Polydorides[80], 2014	46	Female	Colon	No	Abdominal pain, astriction, vomiting (history of Crohn’s disease)	Partial colectomy with end-to-end anastomosis
Lord et al[3], 2015	28	Female	Rectum	No	Astriction, hemafecia, full-thickness rectal prolapse	Laparoscopic surgery and ileostomy
Wang et al[8], 2015	29	Female	Rectum	No	Abdominal pain	ESD
Spicakova et al[6], 2017	45	Male	Rectum	No	Mucopurulent bloody stool (family history of ulceration)	Low anterior resection and prophylactic appendectomy
Spicakova et al[6], 2017	16	Female	Rectum	No	Hemafecia, astriction	Conservative
Ayantunde et al[1], 2016	34	Female	Rectum	No	Tenesmus, mucopurulent bloody stool	Complete dissection from the submucosa is achieved through a vertical mucosal incision
Masood et al[7], 2018	21	Male	Rectum	No	Hemafecia, weight loss	Laparoscopic surgery and ileostomy
Jeruc et al[81], 2019	32	Male	Colon	No	Mucopurulent bloody stool (history of Crohn’s disease)	Total colectomy
Rumi et al[9], 2019	65	Female	Rectum	No	Mucopurulent bloody stool, tenesmus	Anterior resection of the rectum
Abe et al[82], 2021	48	Male	Rectum	No	Hemafecia (intellectual disability, frequently inserting fingers into the anus after defecation)	ESD
Zhou et al[83], 2021	14	Male	Colon transversum	No	Hemafecia, diarrhea, iron-deficiency anemia (history of Crohn’s disease)	Partial colectomy
Zaki et al[5], 2022	58	Male	Rectum	No	Diarrhea	Surgical resection
Chen et al[10], 2023	62	Male	Rectum	Cholecystectomy	Rectal submucosal eminence	ESD
Suter and Skinner[84], 2023	25	Female	Rectum	No	Hemafecia	EMR
Zhang et al[85], 2023	14	Male	Rectum	Transanal resection of the rectal lesions	Hemafecia	Conservative
Jiang et al[4], 2023	34	Male	Rectum	No	Mucous defecation	EMR
Jiang et al[4], 2023	27	Female	Rectum	No	Mucopurulent bloody stool, tenesmus	EMR
Bhagwanani et al[86], 2023	49	Female	Rectum	No	Rectal prolapse	Surgical resection
Denis et al[87], 2024	72	Female	Colon	Sigmoid colectomy for colon cancer (stage T2N0)	Asymptomatic	Right hemicolectomy
Chebbo et al[88], 2024	29	Female	Sigmoid colon	Appendicectomy	Abdominal pain, hemafecia	EMR
Rosano et al[89], 2024	65	Female	Sigmoid colon	No	Abdominal pain, diverticulosis (family history of colon cancer, history of atrial fibrillation)	Laparoscopic sigmoidectomy
Früh et al[90], 2024	82	Female	50 cm from the anal margin	No	Hemafecia	Loop excision
Guduguntla et al[91], 2025	20	Female	Rectum	No	Hemafecia (family history of colon cancer)	No
Zhou et al[92], 2025	48	Male	Colon descendens	No	A mass in the descending colon mucosa	ESD

EMR: Endoscopic mucosal resection; ESD: Endoscopic submucosal dissection.

CCP is a rare and non-cancerous condition marked by several mucus-filled submucosal cysts, typically found in the rectum and sigmoid colon[4]. In medical literature, fewer than 200 cases have been documented. The most common symptoms of CCP include altered bowel habits, rectal tenesmus, hematochezia, mucus secretion in feces, and obstructive defecation. However, the reported patient had no symptoms and were detected incidentally at a medical check-up. Both lesions have approximately the same diameter and histopathological findings, which is very rare. This is inconsistent with previous studies.

The underlying causes of CCP are not fully understood, but a weakness in the mucosal wall, whether congenital or acquired, is thought to be a factor in its development. This vulnerability may be induced by infection, inflammation, ischemia, or trauma, leading to the implantation of mucosal epithelium into the submucosa[4]. There are diffuse and localized types, depending on the level of invasion[5]. In the diffuse type, the entire colon is involved and characterized by ulcers or villous or polypoid lesions, mainly due to intestinal inflammation and ulceration, which is associated with Crohn’s disease, infectious colitis, ulcerative colitis, and radiation enteritis[4]. The local type is mainly observed in the anterior wall of the rectum, manifesting as nodules or polyps. It is associated with rectal prolapse and isolated rectal ulcer syndrome. The literature shows that the local type is the mostly frequent, with the diffuse type comprising less than 15% of cases[6]. A young patient in this study presented with mucous excretion as a clinical manifestation. Located 18-20 cm from the anal verge on the anterior rectal wall, the lesion exhibited nodularity and was classified as the local type, consistent with prior research findings.

With advances in endoscopic ultrasonography (EUS) technology, this method is crucial for pre-surgical diagnosis. It has been reported that there are three main forms of CCP in EUS: (1) Anechoic; (2) Mixed echoic; and (3) Hypoechoic. Under EUS, the typical imaging features of CCP were that the lesions originated from the mucosa or submucosa, and gradually extended to the submucosa or muscularis propria. The echoic area is observed with no color flow imaging. The primary differential diagnosis is mucinous carcinoma, which showed abundant blood flow signal. EUS enables clear identification of the intestinal wall’s distinct layers and assessment of the integrity of the mucosal, muscularis propria, and serosal layers. While EUS cannot definitively diagnose, it is crucial to rule out malignant tumors. Moreover, EUS can be repeated as a follow-up examination. EUS remains there commended as a follow-up management examination. It is easy to perform safe, noninvasive, nonradioactive and well tolerated. In this study, EUS revealed submucosal cystic lesions in both cases, with intact mucosal and serous layers. On CT, CCP manifests as a non-infiltrating submucosal mass with well-defined borders and variable-sized cystic lumens[4]. Magnetic resonance imaging showed low signal on T1-weighted imaging, a submucosal high-signal nodule on T2-weighted imaging, no obvious enhancement on contrast-enhanced sequences, high signal on diffusion-weighted imaging, no diffusion restriction on apparent diffusion coefficient, and marked high signal on T2-weighted imaging - consistent with mucin-containing lesions[7]. Even though colonoscopy provide the benefit of taking biopsies, misdiagnosis can occur when the biopsy depth is limited and the sampling is not enough[4]. Wang et al[8] reported viscous yellow fluid was seen flowing from the lesion during endoscopic resection. Examination of shed showed the presence of neutrophils, lymphocytes, columnar epithelial cells and squamous cells. In our case, the yellow fluid was aspirated by an assistant, and the surgeries were completed uneventfully. This is similar to the study by Wang et al[8]. Ultimately, the definite diagnosis of CCP was eventually determined based on the operative findings and postoperative pathology.

Histologically, CCP is identified as a nonmalignant lesion with submucosal cysts filled with mucin of various sizes, covered by epithelium without atypical cells, extending under the muscularis mucosa and intruding into the muscularis propria in many instances. Moreover, the connective tissue around the lesion may also display signs of chronic inflammation and fibrosis[9].

The main differential diagnosis is benign or malignant colorectal tumors (adenomatous polyps, polypoid inflammatory granulomas, leiomyomas, lipomas, sarcomas, adenocarcinomas, mucinous carcinomas) and inflammatory bowel disease (Crohn's disease, ulcerative colitis and ischemic colitis or proctitis)[5]. Interestingly, intraoperative frozen-section pathology of the patient suggested low-grade mucinous neoplasms. However, the low-grade mucinous neoplasms in most cases are from mucinous tumors arising from the appendix. Subsequently, the patient underwent an appendectomy. The results were described as simple appendicitis. This result differs from the one we imagined. Finally, the conclusion was reached after discussion by the pathologists. This is not low-grade mucinous neoplasms. Ultimately, the patient was diagnosed with CCP. Thus, the differential diagnosis is important.

The treatment of CCP aims to alleviate symptoms. The first step is conservative management with a high-fiber diet and lifestyle changes to avoid constipation and straining during bowel movements. In many instances, conservative treatment is ineffective, requiring surgical intervention for severe bowel obstruction, rectal prolapse, and bleeding. Recently, the use of endoscopic submucosal dissection has become widespread due to its benefits of quick healing, minimal damage, and maintaining colonic integrity[4,10]. In our case, the risk of perforation by endoscopic treatment was concerned. The patient declined any endoscopic therapy, and thus, laparoscopic excision was pursued. Actually, if endoscopic removal fails, surgery is warranted.

CONCLUSION

In summary, it is crucial to identify CCP. Once misdiagnosed, it causes patients to perform unnecessary painful surgeries and brings risks to physicians. It is especially vital for appendectomy patients. Meanwhile, imaging studies with CT and magnetic resonance imaging and EUS significantly contribute to disease detection and the differentiation of malignant conditions, but also limited. Thus, further research is required to distinctly identify and differentiate CCP from other similar conditions.