Simultaneous occurrence of angiomyolipoma and renal cell carcinoma. Clinical and pathologic (including ultrastructural) features.

The clinicopathologic features of an angiomyolipoma and a renal cell carcinoma occurring in the same patient are reported. A seventy-four-year-old woman was thought clinically and radiographically to have renal cell carcinoma of the left kidney with a metastasis to the right kidney. At surgery, however, she was found to have an angiomyolipoma in the right kidney and a renal cell carcinoma confined to the left kidney, both of which were resected with a good prognosis for survival. Light microscopy of the angiomyolipoma showed the characteristic admixture of adipose tissue, spindle cells, and hyalinized blood vessels. By electron microscopy, the spindle cells had cytoplasmic myofilaments and pinocytotic vesicles, and were surrounded by a basal lamina, consistent with a smooth muscle cell origin. This case is of interest in light of genetic influences in both of these neoplasms, and from the point of view of patient management.