Cystic pheochromocytoma: radiologic diagnosis.

Cystic pheochromocytomas are unusual variants of adrenal pheochromocytomas. Computed tomography and pathologic findings in the two cases reported here illustrate three cardinal principles in the diagnosis of cystic pheochromocytomas: (1) A suprarenal cystic tumor discovered on CT may be the result of hemorrhage and necrosis of an adrenal pheochromocytoma. (2) The cystic pheochromocytoma typically exhibits areas of low attenuation, with Hounsfield units in the range of 5 to 15 and rim enhancement on contrast administration. (3) Incidental adrenal lesions with these features discovered on CT scanning are an indication for catecholamine assays to screen for pheochromocytoma.