Small cell carcinoma (SCC) of the bladder is an aggressive, poorly differentiated neuroendocrine neoplasm that is similar to SCC of the lung in clinical behavior. It is a rare neoplasm worldwide. For example, in the United States, it accounts for roughly 500 new cases annually.
Although SCC is classified as a discrete entity, molecular studies have indicated that SCC is derived from the same clonal population as urothelial cancer . Bladder SCC is frequently found in conjunction with other histologic forms of bladder cancer [2-4]. As an example, in a series of 66 cases from one institution, 44 (68 percent) had other tumor types present, including elements of urothelial cancer in 38 cases (58 percent of the total series) . Similarly, a series of 51 cases of SCC at another institution reported that elements of urothelial carcinoma, adenocarcinoma, and squamous cell carcinoma were seen in 70, 8, and 10 percent of the cases, respectively .
SCC of the bladder will be reviewed here. Extrapulmonary SCC at other sites is discussed separately. (See "Extrapulmonary small cell cancer".)
The worldwide incidence of small cell carcinoma (SCC) of the bladder increased significantly from 0.05 to 0.14 cases per 100,000 population, but this still represents less than one percent of all bladder tumors .
In a 2011 analysis of patients with SCC using the Surveillance, Epidemiology, and End Results (SEER) database, the following was noted :