Cutaneous angiomyolipoma. A light-microscopic, immunohistochemical, and electron-microscopic study.

We report a case of cutaneous angiomyolipoma found on the helix of a 67-year-old man. The lesion was studied by routine light microscopy, special stains, immunohistochemical methods, and electron microscopy. Histologic examination showed a well-circumscribed nodule in the dermis composed of an intimate mixture of blood vessels, smooth muscle, and mature fat. These components were confirmed by special stains, immunohistochemistry, and electron microscopy. We concluded that the unique features of this lesion distinguish it from other lesions such as angiomyoma, angiolipoma, and other mixed mesenchymal tumors. This report demonstrates that the features considered diagnostic of angiomyolipoma can occur in extrarenal sites and, therefore, this diagnosis cannot be excluded on the basis of site alone.