Angioleiomyoma within a histiocytoma

We report an angioleiomyoma developed within a cellular histiocytoma on the calf of a 77-year-old man. The lesion consisted of a spherical nodule with two well-defined concentric areas. The outer circular area was a cellular histiocytoma and the inner central area consisted of an angioleiomyoma. Immunoperoxidase investigations for desmin demonstrated positivity in the angio-leiomyoma, whereas the histiocytoma remained negative. Serial sections of the lesion failed to demonstrate a connection between the angioleiomyoma and a normal vein which could have been trapped by the histiocytoma. The angioleiomyoma may have originated from a vessel in the histiocytoma.