Nonfunctioning argyrophilic tumor (APUDoma) of the hepatic duct: simplified methods of detecting biogenic amines in tissue.

This report documents a foregut endocrine neoplasm in an unusual location, the main hepatic bile duct, and describes simplified methods of detecting similar endocrine tumors. Formaldehyde fume-induced fluorescence (FIF) is a quick, specific method to demonstrate biogenic amines. FIF combined with histochemical procedures showing abundant alpha-glycerol phosphate dehydrogenase and esterases indicates the neural crest origin of these and related neoplasms. Amine precursor uptake and decarboxylation (APUD) is a significant marker of these cells and gives them their name.