Small cell carcinoma in a bladder diverticulum: a rare case report and literature review

Background Small cell carcinomas arising from bladder diverticula are extremely rare. The highly malignant nature of small cell carcinoma, combined with the absence of a muscularis propria in the diverticular wall, makes these tumors prone to early invasion and metastasis, resulting in an extremely poor prognosis. Case presentation We report a rare case of small cell carcinoma occurring in a bladder diverticulum. An 80-year-old woman presented to the hospital with gross hematuria. Computed tomography urography and cystoscopy confirmed the presence of tumors within the bladder diverticulum. Partial cystectomy was performed. Histopathological examination of the specimen revealed small cell carcinoma, and perivesical fat tissue invasion and intravascular invasion were detected. Radical cystectomy, adjuvant chemotherapy, and radiotherapy were refused. Later, tumor recurrence occurred, and the patient died 8 months after surgery. Conclusion Small cell carcinoma of the bladder diverticulum represents an extremely rare and aggressive malignancy, with only a handful of cases reported in the medical literature. This scarcity poses significant diagnostic and therapeutic challenges and underscores the need for increased awareness and further research to improve understanding and management of this complex condition.