INFILTRATING RENAL ANGIOMYOLIPOMA INTO ASCENDING COLON ASSOCIATED WITH HEPATIC INVOLVEMENT IN A PATIENT WITH TUBEROUS SCLEROSIS

Abstract

Angiomyolipoma is the most common mesenchymal tumor of the kidney and is composed of a heterogeneous mixture of adipose cells, thick walled blood vessels and smooth muscle in haphazard pattern. It is relatively slow growing and usually has a benign clinical course. 1 On rare occasions, renal angiomyolipoma has infiltrating growth, extensive destruction and local recurrence with a fatal outcome. We report an infiltrating renal angiomyolipoma with recurrence at the ascending colon in a patient with tuberous sclerosis. CASE REPORT A 31-year-old woman with tuberous sclerosis presented with an abdominal mass. Computerized tomography revealed bilateral renal tumors with fat contents. The left kidney was resected. Intraoperatively, a small liver nodule was also noted. A year later the patient had a sudden onset of right flank pain and gross hematuria. The right kidney was removed. The left and right kidneys measured 20 3 12 3 10 cm. and 27 3 18 3 14 cm., respectively. Bilateral kidneys were largely replaced by a gray-yellow confluent solid mass. Massive hemorrhage was noted in the right renal mass. Histological examination revealed that bilateral renal tumors were comprised of fat tissue, smooth muscle and blood vessels, which were characteristic of angiomyolipoma. Both renal tumors showed an infiltrating growth with entrapment of renal tubules (part A of figure ). There was no obvious cytological atypia. The liver nodule was composed of solid sheets of epithelioid myoid cells admixed with some adipocytes and abnormal vessels (part B of figure). The patient returned with bloody stool 1 month after the second operation. At laparotomy a colonic tumor was found at the ascending colon. The colonic tumor showed infiltrating bundles of smooth muscle with few fat cells and blood vessels under the mucosa (part C of figure). Immunohistochemical study revealed that the infiltrating smooth muscle bundles were positive for HMB-45 (part D of figure). The patient died of postoperative pneumonia. DISCUSSION