Immunohistochemical study of pheochromocytomas. An investigation of methionine-enkephalin, vasoactive intestinal peptide, somatostatin, corticotropin, beta-endorphin, and calcitonin in 16 tumors.

Immunohistochemical investigations were carried out on 16 pheochromocytomas for a study of their immunoreactivity to methionine-enkephalin, vasoactive intestinal peptide, somatostatin, corticotropin, beta-endorphin, and calcitonin on serial semithin araldite sections. All antiserums except anti-beta-endorphin, selectively stained a variable number of distinct tumor cells. Methionine-enkephalin-immunoreactive cells were the most frequent. The neuropeptide content of pheochromocytomas appears highly diverse and unpredictable. These findings are supportive of the concept of multisecretory APUD cells of neural crest origin and rule out any of these neuropeptides as reliable immunohistochemical markers for tumor chromaffin cells.