Lipid degeneration in pheochromocytomas mimicking adrenal cortical tumors.

A case of bilateral adrenal pheochromocytomas with unusual morphologic features is reported in a 27-year-old man with a family history of von Hippel-Lindau disease. In both glands, the medulla was replaced by neoplasms with two distinct gross and microscopic appearances. There was typical pheochromocytoma in areas of dusky red tissue. The yellow nodules noted on gross examination were microscopically composed of large cells with vacuolated cytoplasm. Fat stains confirmed the presence of lipid in these areas. Immunohistochemistry revealed positivity for neuron-specific enolase and chromogranin in the cytoplasm of pheochromocytes, as well as in the perinuclear cytoplasm and processes of cells scattered in the yellow nodules. Ultrastructural examination of the yellow lesions showed characteristics of pheochromocytoma and an extensive accumulation of lipid. Although gross and light-microscopic examination of the yellow tissue suggested adrenal cortical nodules, immunohistochemistry and electon microscopy elucidated lipid degeneration within pheochromocytoma, a finding not previously described.