OBJECTIVETo investigate the clinicopathological characteristics and the prognosis of bladder neuroendocrine carcinoma (NEC).

METHODSClinicopathological data from 17 NEC of the bladder cases were collected, and immunohistochemical staining was performed with follow-up analysis and literature review.

RESULTSThe recruited included 13 male and 4 female patients, aged from 48 to 86 years old (average 61 years; 14 patients >60 years). Gross hematuria of the whole urination course or intermittent was the initial symptom. Macroscopically, the outer surface of the tumor presented with polypoid, lobulated, fungating or ulcerous structures. Histologically, according to the criteria of WHO classification of neuroendocrine tumor of the lung, our NEC cases were divided into three histological types: 13 cases of small cell carcinoma, 3 cases of large cell neuroendocrine carcinoma and 1 case of atypical carcinoid. The urothelial carcinoma was concurrent with NEC in 6 cases, and adenocarcinoma was concurrent with NEC in 2 cases. Most tumor tissue infiltrated to the muscular layer, some infiltrated to the outer membrane. Immunohistochemically, the positive expression rates of CD56, Syn and CgA were 16/17, 16/17 and 12/17, respectively. The epithelial markers, including CK7 and CKpan, were also expressed with positive rates of 12/17 and 15/17, respectively. TTF-1 was positively expressed in 11 cases. The follow-up data were available in 14 cases, of which 9 patients died of the tumor 1-34 months after surgery (average, 11 months). Five patients lived uneventfully for 1-12 months after surgery.

CONCLUSIONSNEC is a rare malignant tumor of the bladder. Immunohistochemical markers such as CD56, Syn, CgA and CKpan could be helpful in determining the diagnosis and differential diagnosis of the tumor. NEC is a highly invasive malignant tumor with poor prognosis. Based on its biological behavior, radical cystectomy is the preferred method of treatment for the tumor.