There are two types of chromaffin cell neoplasms: the pheochromocytoma which is a neoplasm of the medullary parenchyma of the adrenal medulla and the paraganglioma which is a neoplasm of chromaffin cells elsewhere in the body. Chromaffin cells are those cells that have an affinity for the dichromate containing stains. In the presence of these stains these cells become brown in color as they are in this specimen. Some chromaffin cells produce catecholamines. About 85% of phaechromocytomas are sporadic, in contrast to the remaining 15% which are part of a familial neoplastic syndrome such as the mutliple endocrine neoplasia syndromes. Clinically these patients present with a constellation of symptoms related to the paroxysmal release of catecholamines from the neoplasm. About 93% of these neoplasms are benign.