[A poorly differentiated apudoma of the gallbladder].

Apudoma was found in the gall bladder removed in a 76-year-old woman because of the chronic calculous cholecystitis exacerbation. Carcinoid syndrome was absent clinically. Histologically, the tumour was a poorly differentiated carcinoid with areas of small cell and polymorphic carcinoma. Argyrophilic Pasquale reaction in the tumour cells was negative, electron microscopically small neurosecretory granules were found. Numerous ACTH-reactive cells and single serotonin-reactive cells were revealed in the tumour parenchyma by means of immunohistochemical PAP-method using antibodies against ACTH, serotonin, calcitonin, somatostatin, insulin, glucagon, P-substance. Focal hyperplasia and intestinal metaplasia of epithelium with the increase of the number of argyrophilic, ACTH-reactive cells were observed outside the tumour.