Proopiomelanocortin mrna expression by small cell bladder carcinoma associated with cushing's syndrome: diagnostic contribution of in situ hybridization.

A case of ectopic ACTH secretion by primary small-cell carcinoma of the urinary bladder is described. The patient, a 38-year-old woman, presented with Cushing's syndrome. Although immunocytochemistry of the tumor for ACTH and corticotropin-releasing factor yielded negative results, in situ hybridization demonstrated a conclusive signal for proopiomelanocortin messenger RNA.