Differential diagnosis of pheochromocytomas and paragangliomas.

Paragangliomas are of two types, sympathetic and parasympathetic, depending on the type of paraganglion in which they arise. The term pheochromocytoma is reserved for tumors arising in the adrenal medulla. These tumors are usually fairly easy to diagnose. However, several areas are the subject of debate, including the identification of malignant potential, the diagnosis of medullary hyperplasia, and the recognition of composite tumors. Some histologic features can cause problems in differential diagnosis. Paragangliomas may have spindle cell morphology or contain pigment, requiring distinction from mesenchymal tumors and melanoma, respectively. Extensive degenerative change in pheochromocytomas may mimic adrenal cortical tumors. This short review addresses the diagnosis of pheochromocytomas and paragangliomas and discusses useful approaches in the aforementioned problem areas.