Small Cell Carcinoma of the Bladder

Definition

Carcinoma of the bladder composed of uniform cells with scant cytoplasm and neuroendocrine features

Appearance is identical to that of small cell carcinoma of the lung
- Scant cytoplasm, very high nucleus/cytoplasm ratio
- Finely granular, stippled chromatin
- Nucleoli small to absent
- Nuclear molding
- Very high mitotic rate
- Immunohistochemical demonstration of neuroendocrine differentiation not required
  - Many are positive for synaptophysin
Frequently mixed with other types of carcinoma
- Any component of small cell carcinoma determines behavior
Large cell neuroendocrine carcinoma is exceedingly rare in the bladder

Robert V Rouse MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342