Surgical specimens of 72 adrenocortical tumours were investigated by conventional histology, immunocytochemistry and DNA-cytophotometry. Histologically, 57 tumours were classified as adenomas and 15 as carcinomas. Nine adenomas weighed more, 2 carcinomas less than 50g. Only in 9 of the latter cases were distant metastases and/or lethal outcome of disease recorded, while the clinical course of the remaining patients was uneventful. No significant differences in DNA content were found between adenomas and carcinomas or between carcinomas with aggressive and indolent behaviour. Neither could immunocytochemistry discriminate between these conditions. Immunostaining with the monoclonal antibody D 11 proved to be the only effective means to definitely type adrenocortical neoplasia. Thirty-one cases exhibited positivity upon immunostaining with a polyclonal antiserum against synaptophysin. This phenomenon has so far not been encountered in non-neuroendocrine neoplasia.
