Small cell carcinoma encountered in a urinary bladder diverticulum.

Received December 2007 Accepted May 2008 INTRODUCTION Bladder tumors arising within a diverticulum are uncommon and pose a unique diagnostic and therapeutic challenge. The reported incidence ranges from 0.8% to 10.0%, with the most common histological subtype being transitional cell carcinoma followed by squamous cell carcinoma.(1) Additionally, small cell carcinoma of the bladder is a rare and highly aggressive tumor which tends to progress and metastasize within a few months after diagnosis and provides very poor prognosis.(2) It presents with the histopathologic, immunohistochemical, and ultrastructural characteristics and light microscopic features common to all neuroendocrine tumors observed in other organs, especially the lung.(3) Since Cramer and colleagues(4) reported the first case of a small cell carcinoma of the urinary bladder in 1981, nearly 160 cases have been reported.(5) However, small cell carcinoma encountered in a bladder diverticulum has been described in only 5 patients in the literature.(4,6-8) We present a new case of this rare entity disease.