ISOLATED FIBRINOID VASCULITIS IN RENAL ANGIOMYOLIPOMA

Renal angiomyolipoma is a tumor composed of a mixture of thick-walled blood vessels, smooth muscle, and mature adipose tissue. It may presen t as a single unilateral lesion or as a multifocal uni- or bilateral n eoplasm, The histologic spectrum of angiomyolipoma is wide but as far as we know intratumoral fibrinoid vasculitis has not been described in the tumor. This is the first report of isolated intratumoral fibrinoi d vasculitis observed in two nodules of a unilateral multifocal renal angiomyolipoma. The vasculitis arose in a hypertensive 62-year-old wom an who presented with a history of dull right flank and low back pain of 3 months' duration. There were no signs of generalized disease. Imm unophenotyping of the vascular cellular infiltrate disclosed abundant T lymphocytes, significant numbers of histiocytes, and absence of B ly mphocytes. The diagnosis of isolated intratumoral arteritis depends on the exclusion of systemic disease. It is important to distinguish cas es like this one to avoid misdiagnosis and to prevent unnecessary trea tment.