Composite pheochromocytoma: a clinicopathologic and molecular comparison with ordinary pheochromocytoma and neuroblastoma.

Composite pheochromocytoma is a rare adrenal tumor composed of ordinary pheochromocytoma and other components, most frequently neuroblastic elements. Little is known about its biologic potential, therefore creating a clinical dilemma on diagnosis. This study investigates the clinical characteristics and N-myc amplification status of 4 cases of composite pheochromocytoma and compares them with selected cases of ordinary pheochromocytoma and neuroblastoma. The age range of the patients with composite pheochromocytoma was 15 to 40 years with an equal M/F ratio, including 2 patients with syndromes. None of these composite pheochromocytomas demonstrated N-myc amplification, none recurred, and there were no deaths. Of the classic pheochromocytomas, none demonstrated N-myc amplification, 2 recurred, and there were no deaths. Of the neuroblastomas, 5 (50%) of 10 showed significant N-myc amplification, and there were 4 known recurrences and 5 known deaths. These findings suggest that composite pheochromocytoma may be regarded as a histologic variant of classic pheochromocytoma.