Tc-99m MIBG imaging in a huge clinically silent pheochromocytoma with cystic degeneration and massive hemorrhage.

I-131 metaiodobenzylguanidine scintigraphy showed marked accumulation in the walls of a clinically silent, huge cystic adrenal mass with a prominent hemorrhage in a 48-year-old man. Although a careful reexamination of the histologic specimen finally lead to a diagnosis of pheochromocytoma, the appearances of this mass on computed tomography and magnetic resonance imaging were not specific for this neoplasm, and even pathologic analysis initially indicated, incorrectly, that this lesion was a hemorrhagic hemangioma. This case shows that I-131 metaiodobenzylguanidine scintigraphy is useful for correctly diagnosing an adrenal mass with prominent cystic or hemorrhagic degeneration.