Pheochromocytoma associated with neuroendocrine carcinoma - A new type of composite pheochromocytoma

The coexistence of pheochromocytoma and other tumor types in a single adren al gland has been rarely documented. This type of pheochromocytoma is desig nated "composite" or "mixed," depending on whether the pheochromocytoma and the nonpheochromocytoma components show the same embryologic origin. The n onpheochromocytoma components reported in the composite pheochromocytoma in clude ganglioneuroma, ganglioneuroblastoma, neuroblastoma, and malignant sc hwannoma. The components found in the mixed pheochromocytoma include adrena l cortical neoplasms and spindle cell sarcoma. We report a unique case of c omposite pheochromocytoma in which the nonpheochromocytoma element is a neu roendocrine carcinoma. The histologic and the immunohistochemical profiles of the 2 distinct components of this tumor were typical for those of pheoch romocytoma and neuroendocrine carcinoma. This dual differentiation was also supported by ultrastructural findings. This case not only broadens the mor phologic spectrum of composite pheochromocytoma but also provides some addi tional insight into the histogenesis of this rare but fascinating type of t umor.