Plasmacytoid urothelial carcinoma of the urinary bladder with colorectal metastasis and mimicking colitis: A case report

Abstract

BACKGROUND

Plasmacytoid urothelial carcinoma (PUC) is a rare histologic variant of urothelial carcinoma. PUC is characterized by aggressiveness and poor prognosis. Since the first reported case of PUC in 1991, approximately 100 cases have been documented. In patients with PUC, colorectal metastasis is an uncommon presentation that is difficult to diagnose because it can mimic colitis on imaging examination, exhibiting colorectal wall thickening with a preserved vesicorectal fat plane. The pathogenesis of urologic malignancies that metastasize to the colon remains unclear.

CASE SUMMARY

A 65-year-old Taiwanese man presented to our emergency department with a 3-month history of progressive abdominal fullness. A month before presentation, he had visited our hospital for gross hematuria with hydronephrosis and was subsequently hospitalized in our urology ward for transurethral resection of a bladder tumor. Postoperative histopathologic examination confirmed PUC. Regarding the illness at presentation, abdominal computed tomography revealed diffuse distension of the small and large intestines and long segmental thickening of the rectosigmoid colonic wall. Conservative management—empirical antibiotics, bowel rest, nasogastric tube decompression, and intravenous fluid support—was initiated with a presumptive diagnosis of colitis. Because of the patient’s inadequate response to conservative management, a diverting ileostomy was performed, which relieved the abdominal distension. Subsequent colonoscopic and histopathologic examinations with immunohistochemical staining confirmed colorectal metastasis through an atypical metastatic route.

CONCLUSION

Our case highlights diagnostic challenges posed by atypical imaging findings and unusual etiologies of gastrointestinal wall thickening with peripheral infiltration.

Key Words: Urothelial carcinoma; Plasmacytoid; Colorectal tumor; Colitis; Case report

Core Tip: This report describes a case of colorectal metastasis in a 65-year-old man with plasmacytoid urothelial carcinoma. The patient had hospitalization with the impression of colitis with ileus initially for the image disclosed diffused bowel distension and long segmental rectosigmoid colonic wall thickening, with clear vesicorectal fat plane. And the colorectal metastasis with an unusal hypothesized pathogenesis was detected and confirmed by endoscopy and pathologic examinations with immunohistochemical staining. This case underscores the uncommon image findings and atypical pathway of metastases of bladder cancer to gastrointestinal tract.

INTRODUCTION

Plasmacytoid urothelial carcinoma (PUC) was first reported in 1991 as a rare histologic variant of urothelial carcinoma. PUC is characterized by discohesive tumor cells that morphologically resemble plasma cells, with eccentric nuclei and eosinophilic cytoplasm[1,2]. These cells express CD138, which reflects their plasmacytoid morphology, and typically exhibit strong immunopositivity for CK7, CK20, and GATA-3, which serve as biomarkers of urothelial cancers including PUC. These features help differentiate PUC from signet ring cell carcinoma, which has similar histomorphology, characterized by discohesive tumor cells, eccentric hyperchromatic nuclei, and eosinophilic cytoplasm. Furthermore, p63 immunostaining can help differentiate urothelial carcinoma from prostatic adenocarcinoma in complex cases[3]. PUC is characterized by aggressiveness, with a propensity for diffuse infiltration rather than discrete mass formation and a strong tendency for intraperitoneal dissemination[4]. Clinically, patients with PUC often present with hematuria and nonspecific urinary symptoms such as dysuria, frequency, urgency, or urinary retention; however, initial manifestations may also include distant metastases or peritoneal dissemination[5]. PUC can manifest as unusual gastrointestinal symptoms rather than those typical of urothelial carcinoma. Thus, a comprehensive histologic examination is required to determine the presence and extent of metastasis. Given the rarity of PUC, very few autopsy reports are available[6-8]. Herein, we report the case of a patient with urinary bladder PUC who initially presented with progressive abdominal fullness, nausea, and reduced appetite due to tumor infiltration of the colon and rectum and eventually received a diagnosis of colorectal metastasis. Our case features atypical imaging findings and unusual etiologies of gastrointestinal wall thickening with peripheral infiltration.

CASE PRESENTATION

Chief complaints

A 65-year-old Taiwanese man presented to our emergency department with a 3-month history of progressive abdominal fullness.

History of present illness

The patient first noted abdominal fullness, particularly after food intake, approximately 3 months before their presentation, and this fullness worsened over the following months. Initially, the symptoms were relieved with rest. However, the response to lifestyle modifications, such as a bland diet and increased physical activity, became inadequate over time. The patient also reported nausea, reduced appetite, and changes in bowel habits, including frequent diarrhea. Moreover, vomiting episodes occurred in the days leading up to his hospital visit.

History of past illness

The patient had a history of hypertension managed with medication. Approximately 1 month before presentation, he visited our urology department for painless gross hematuria, which developed approximately 2 months after the onset of the abdominal symptoms. He denied having any other urinary symptoms. Imaging examinations revealed a bladder tumor on the left side. He was subsequently hospitalized in the urology ward for transurethral resection of the bladder tumor. Postoperative histopathologic examination confirmed PUC.

Personal and family history

The patient had a healthy lifestyle without relevant occupational or social risk factors. Furthermore, he had no known family history of major illnesses or genetic disorders.

Physical examination

Physical examination revealed a distended abdomen with generalized tympany and hyperactive bowel sounds.

Laboratory examinations

Laboratory tests revealed leukocytosis (29640/μL) and an elevated C-reactive protein level (161.46 mg/L). However, the patient’s hemoglobin level, liver and renal function test results, and serum electrolyte levels were within normal limits.

Imaging examinations

Abdominal computed tomography (CT) revealed diffuse distension of the small and large intestines and long segmental thickening of the rectosigmoid colonic wall, with a preserved vesicorectal fat plane (Figure 1A and B). Colonoscopy revealed luminal obstruction with edematous mucosal changes up to 5 cm from the anal verge (Figure 1C). Multiple deep biopsies were conducted.

Figure 1 Preoperative evaluation. A: Diffuse distension of the small and large intestines on axial-view abdominal computed tomography; B: Long segmental thickening of the rectosigmoid colonic wall and perirectal fat stranding with a clear vesicorectal fat plane (white arrow) on sagittal-view abdominal computed tomography; C: Obstructed lumen with mucosal swelling (white circle) located up to 5 cm from the anal verge on colonoscopy.

Given the patient’s inadequate response to conservative management—empirical antibiotics, bowel rest, nasogastric decompression, and intravenous fluid support—an exploratory laparotomy was performed. Intraoperatively, the small intestine was found to be distended from the ligament of Treitz to the ileocecal valve and ascending colon, without any evidence of adhesions or a clear obstructive lesion. Long segmental wall thickening and marked pericolic inflammation were observed from the rectum to the sigmoid colon. A diverting loop ileostomy was performed to decompress the distended intestinal tract (Figure 2). After surgery, the abdominal fullness resolved and normal stool passage through the ileostomy was noted. Histopathologic examination of the colonoscopic biopsies revealed infiltration by PUC cells (Figure 3A and B), which were positive for GATA-3 and p63 on immunostaining (Figure 3C and D), consistent with the histology and immunohistochemistry after transurethral resection of the bladder tumor.

Figure 2 Intraoperative images. A: Distension of the intestine from the ligament of Treitz to the ileocecal valve and ascending colon; B: No apparent adhesion or obstructive lesion observed after manual decompression; C: Distended sigmoid colon with marked inflammatory changes in the colonic wall extending from the sigmoid colon to the rectum (white circle), without any evidence of urinary bladder invasion (white arrowhead).

Figure 3 Histopathologic findings. A: Discohesive tumor cells infiltrating the muscularis mucosa of the colon (black circle; hematoxylin–eosin staining, × 100); B: Plasmacytoid cells with abundant eosinophilic cytoplasm (black circle) and eccentric nuclei (black arrowhead; hematoxylin–eosin staining, × 400); C: Immunohistochemical staining for GATA-3 indicated nuclear positivity (black box; immunoperoxidase method, × 200); D: P63 staining revealed nuclear positivity (black box; immunoperoxidase method, × 200).

FINAL DIAGNOSIS

The patient received a final diagnosis of PUC with rectosigmoid colonic metastasis.

TREATMENT

The patient was referred to a urologist for further management. After a multidisciplinary conference was held, a radical cystectomy, to be followed by systemic chemotherapy plus targeted therapy, was scheduled.

OUTCOME AND FOLLOW-UP

During radical cystectomy, peritoneal carcinomatosis was observed; hence, the surgery was aborted. The urologist informed the patient and family of the unfavorable operative findings, poor prognosis, and limited response expected from systemic therapy at this advanced stage. The patient and family opted for comfort care and declined further aggressive or invasive interventions. Thus, the patient was referred to the palliative care unit for hospice management. He passed away approximately 3 months after the PUC diagnosis was made.

DISCUSSION

PUC accounts for 1%–3% of all bladder cancer cases. It is associated with adverse clinicopathologic features, advanced stage at cystectomy, and poor prognosis[2,9-13]. Some reports have reported that PUC invades along the perirectal or perivesical fascial plane[9,12,13], a pattern that is difficult to detect through conventional CT or magnetic resonance imaging[14]. The median duration of survival in patients with PUC is 17.7 months, with the duration being lower in patients with stage IV disease (13.3 months) than in those with stage I–III disease (45.8 months)[15]. In our case, the patient died approximately 3 months after the confirmed diagnosis of bladder cancer was made. This duration is shorter than that reported in the literature, likely attributable to the fact that our patient received only hospice care without systemic therapy. A similar trend was observed in a study exploring treatment patterns and the benefits of neoadjuvant chemotherapy for patients with PUC, which reported a significant difference in survival duration between patients receiving neoadjuvant chemotherapy and those not receiving it[16]. In our case, PUC was diagnosed following a presentation of painless gross hematuria. The patient’s history of intermittent abdominal fullness over 3 months indicated colonic involvement. The rarity and atypical presentation of PUC complicate its early diagnosis. The colon and rectum are less common sites of metastasis compared with other organs, such as the lungs, liver, and brain. Metastases to the colon and rectum are rarely observed in other cancers. Only one study reported a case of gastric cancer with metastases to the colon[17]. In that case, the metastatic gastric cancer mimicked primary colon cancer on imaging examinations. The final diagnosis was made through histologic examination and immunohistochemical staining for CDX-2, CK7, and CK20.

PUC rarely metastasizes to the gastrointestinal tract. A study investigating the correlations between metastatic patterns and primary bladder tumor characteristics reported that only 3% of all primary bladder cancer cases involve metastasis to the intestines[18]. Lesions may spread to the colon through lymphovascular or direct extension invasion routes. Lymphovascular spread is generally associated with regional lymphadenopathy, which was not observed in our patient, making this pathway unlikely. The mechanisms of extension invasion through which urologic malignancies metastasize to the colon remain unclear. Several studies have proposed different hypotheses. One study suggested that a history of surgical exposure can induce malignant deposition[19]. However, the absence of a history of pelvic surgery in our patient precludes this route. Another study proposed directional invasion, wherein cancer cells breach the bladder wall and extend to the colon through Denonvilliers’ fascia[20]. This route was also unlikely in our case because no directional invasion between the colon and bladder was detected. Kobayashi et al[21] suggested metastasis from the bladder’s lateral pedicles to the posterior rectal wall, followed by permeation into the colorectal wall, resulting in wall infiltration[21]. This route appears most plausible in our case because it aligns with the CT findings. However, our case is unique because of the sequence of symptom presentation. Most cases of bladder cancer with colorectal metastases initially manifest with urinary symptoms, such as gross hematuria, dysuria, or urinary retention. This observation is consistent with the findings of a study reporting that rectal involvement was detected, on average, 13.5 ± 11.8 months after the initial diagnosis of bladder urothelial carcinoma[22]. The initial gastrointestinal presentation in our case could have led to misdiagnosis and inappropriate treatment.

The present case highlights factors that may lead to misdiagnosis in cases of PUC. Abdominal CT images revealed segmental thickening of the colorectal wall, accompanied by pericolic inflammation. Differentiating colitis from tumor infiltration solely on the basis of imaging data—without endoscopic and histologic examinations—can be challenging. A study reported a case of recurrent colon cancer diagnosed 13 years after resection, presenting with gross hematuria[23]. In that case, diagnosis was confirmed through CT and histologic examination. Given the risk of metastasis, patients with a history of cancer or unexplained symptoms should be comprehensively evaluated, including through CT, endoscopy, and histopathology. Immunohistochemical staining can also aid in establishing the diagnosis and guiding therapeutic strategies. Metastasis to the colon may occur through embolic, lymphovascular, or direct invasion routes. In our case, metastasis was initially excluded because of the absence of regional lymphadenopathy and directional invasion to the rectum on CT. Nevertheless, a review of the literature indicated that metastasis from the bladder’s lateral pedicles to the posterior rectal wall was the most likely route.

CONCLUSION

Although the colon and rectum are less commonly affected by metastatic lesions than are other organs, colonic and rectal metastases should still be considered in urothelial carcinoma and PUC. Our case involved PUC with metastasis to the rectosigmoid colon, mimicking the colitis symptoms of colorectal wall thickening and pericolic infiltration on CT. Given the high risk of misdiagnosis, clinicians must maintain a high index of suspicion when encountering cases that resemble colitis.