Malignant epithelioid hemangioendothelioma arising in an intramuscular lipoma
A malignant epithelioid hemangioendothelioma (EH) developed within a peripheral intramuscular lipoma. It was seen as a painful calf mass. At the time of biopsy and en bloc resection, lung metastases were observed. Radiologic, histologic, immunohistochemical, and ultrastructural features of the neoplasm are described, and the literature pertaining to EH is reviewed. The features of this tumor permitted its classification as a malignant EH. This case illustrates the potential for aggressive behavior in an EH, often considered to be a low-grade malignant neoplasm. Because such tumors can metastasize, they should be removed with wide margins whenever possible. This malignant neoplasm was located within a benign intramuscular lipoma, demonstrating the diagnostic problem that may exist in such a complex lesion.