Renal angiomyolipoma is rare and mostly associated with tuberous sclerosis. Herein is reported a case of primary angiomyolipoma without tuberous sclerosis which occurred in the renal sinus. Such a case is of exceptional rarity and very interesting because it must be considered in the differential diagnosis of parapelvic cyst.
A 50-year-old female visited our hospital on December 12, 1972, complaining urethral bleeding after the resection of caruncle. She had pain in the right flank. Physical examination revealed no abnormal mass. Blood pressure was 150/100. On intravenous pyelography a right pelvic deformity was found. The retrograde pyelogram demonstrated a compressed renal pelvis and dilated calyces. The responsible lesion seemed to extend out of the sinus and compressed the upper ureter from medial side. This finding was thought to be not compatible with parapelvic cyst. Nephrotomography combined with contrast medium infusion and pneumoretroperitoneum was performed and the mass was poor in vessels. Arteriography was not done. Stigmata of the tuberous sclerosis complex were not evident.
On January 17, 1973, under general anesthesia exploration was carried through transabdominal approach. An encapsulated yellow tumor arising from the right renal sinus extended out of the hilus and downward along the inferior vena cava. The right kidney and the mass were removed. The patient was uneventful postoperatively.
The yellow lipoma-like tumor measured 8.0×4.0×4.0cm. The exact site of origin was difficult to determine. On microscopic examination the tumor was mainly consisted of abundant mature fatty tissue. There were scattered patchy foci of abnormally thick walled vessels surrounded by cuffs of slender smooth muscle cells irradiating from the wall. Those angiomatous vessels were composed of smooth muscle cells resembling arterial wall but had no elastic fiber. The tumor was considered to be a hamartoma rather than true neoplasm. The renal parenchyma showed the picture of chronic pyelonephritis. Calyces were compressed and enlarged.
Prince and associates, reporting their 30 cases, noted that most of the tumor located within the parenchyma of the kidney. The case reported by Appel and associates, however, had a myxoma in the renal sinus which compressed collecting system, resembling parapelvic cyst. In case of angioendothelioma reported by Prince and associates the pelvis was flattened ventro-posteriorly. Such mesenchymal tumors must be considered in the diagnosis of parapelvic space occupying lesions.