Angiomyolipoma of the kidney--an immunohistochemical study.

The study included 25 patients with angiomyolipoma of the kidney. None of them had any signs of tuberous sclerosis. Serious clinical complications such as massive hemorrhage (2/25) and hydronephrosis (2/25) were documented in four patients. Concomitant adenoma of the adrenal gland and renal cell carcinoma were found in one patient each. All tumors consisted of a differing mixture of mature adipose tissue, smooth muscle cells and blood vessels, with thickened walls devoid of elastic lamina. Immunohistochemically, the smooth muscle cells stained strongly with antibodies against vimentin, desmin and actin, as well as HMB-45 and NKI/C3. Immunohistochemical staining for NKI/C3 was stronger and more diffusely distributed. These two markers proved to be very useful in the diagnosis of angiomyolipoma, when only needle biopsy specimens are available.