An immunohistochemical study of pheochromocytomas.

Twenty -six adrenal pheochromocytomas and four normal adrenal medullae were studied immunohistochemically. These included four malignant tumors with proven metastases, six tumors in patients with neurofibromatosis, nine tumors in patients with multiple endocrine neoplasia type 2, and seven sporadic nonfamilial pheochromocytomas. Immunohistochemical localization of neuron-specific enolase (NSE) was seen in all tumors and in the four normal adrenals. Methionine enkephalin-like immunoreactivity was present in tumors from all four groups and in the normal adrenals. Corticotropinlike immunoreactivity was found focally in two normal adrenal medullae and in four benign pheochromocytomas. Our results indicated that NSE was present in all four major groups of pheochromocytomas, including benign and malignant tumors. This marker aided in distinguishing between adrenal cortical and medullary tumors in unusually difficult cases, since all normal adrenal cortex and adrenal cortical tumors had negative test results for NSE.