Abstract
BACKGROUND: Large cell neuroendocrine carcinoma (LCNEC) of the bladder is a rare non-urothelial tumor of the bladder. The treatment of LCNEC of the bladder is different from that of urothelial carcinoma (UC); therefore, early and accurate diagnosis is particularly important. As LCNEC of the bladder is rare and its clinical symptoms and radiographic features are similar to those of urothelial tumors, the clinical diagnosis of the disease remains challenging. CASE SUMMARY: We report a 72-year-old female patient who presented with gross hematuria for 3 mo. A solitary tumor located in the anterior wall of the bladder was found by cystoscopy. Pathological examination after biopsy suggested UC of the bladder in the absence of immunohistochemical assessment. The patient underwent partial cystectomy and was finally diagnosed with LCNEC (pT2bN0M0) based on the results of postoperative immunohistochemical examination. During the 10-mo follow-up, no signs of tumor recurrence or metastasis were found. CONCLUSION: Immunohistochemical examination is essential for diagnosing LCNEC of the bladder. Accurate diagnosis and multidisciplinary treatment in the early stage of the disease are crucial for improving the prognosis.