Epithelioid hemangioendothelioma

Epithelioid hemangioendotheliomas (EHE) are malignant vascular tumors that can occur at any age, but are more common in the second decade of life. Women are slightly more frequently affected than men. Typically they develop as soft tissue tumors of the extremities, but they can be found in almost every part of the human body because of their relation to blood vessels. Clinically, a slightly painful soft tissue mass is seen. When epithelioid hemangioendothelioma develops in large blood vessels, similar symptoms to those of vascular occlusion occur. Epithelioid hemangioendotheliomas can dilate the blood vessels, occlude the lumen and from there spread to the surrounding soft tissue. Microscopically, strands and clusters of epithelioid cells can be seen in a so-called myxohyaline stroma. The cells have an eosinophilic cytoplasm and form small vacuoles (“blister cells”). Fragmented erythrocytes are visible in some of these vacuoles. The degree of atypia is usually rather low here. The cells of the epithelioid hemangioendothelioma typically express the following vascular markers: CD34, CD31, FLI1 and ERG. Cytokeratin expression is also found in 25−40% of cases. The prognosis of most epithelioid hemangioendotheliomas is relatively good, but 20–30% metastasize. About 15% of patients with epithelioid hemangioendothelioma die from this disease.