SECTION EDITOR: EDWARD B. STELOW, MD
Epithelioid hemangioendothelioma (EHE) is a vascular tumor with epithelioid morphologic characteristics. Unlike clearly benign vascular lesions, such as epithelioid (histiocytoid) hemangioma, EHE is classified as a malignant neoplasm based on World Health Organization classification of soft-tissue tumors. This is because approximately 30% of EHE cases feature marked cytologic atypia, foci of necrosis, and high mitotic activity. The local recurrence rate is about 20%, and in its classic form, the metastatic rate is less than 20% and mortality is around 3%.1 Usually, EHE presents in the extremities of adults as a painful, deep soft-tissue mass, although the primary tumor sites in the bone, liver, and lung are also well described. Histologically, EHE consists of rounded eosinophilic cells, organized in strands, cords, or solid nests, sometimes harboring intracytoplasmic vacuoles. There is usually a myxochondroid background and low mitotic activity. Immunohistochemical analysis is useful in diagnosis, as EHE expresses factor VIII–related antigen, CD31, CD34, and the nuclear transcription factor FLI1.1,2
Pathology Quiz Case 2: Diagnosis. JAMA Otolaryngol Head Neck Surg. 2013;139(3):320. doi:10.1001/archotol.139.3.320
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