Answer: Epithelioid hemangioma

Histology: At low magnification, the lesion appears to have a somewhat lobular/oval appearance. At low magnification one can appreciate that there is a significant red blood cell component to the lesion. At higher magnification, especially toward the periphery of the nodules, one can make out some well-formed vessels. In the center of the lesion, the vascular appearance becomes more complex with some spindling and a more solid appearance. Numerous extravasated red blood cells are present. In the center of one of the nodules there appears to be a feeder large vessel with epithelioid appearing epithelial cells that are piled up. The remaining endothelial cells also appear swollen almost occluding the lumina with a very epithelioid appearance. Associated with the vascular proliferation is a prominent inflammatory component consisting of lymphocytes as well as in areas numerous eosinophils.

Discussion: This lesion has the classic appearance of an epithelioid hemangioma. A synonym used for this lesion that is more descriptive is angiolymphoid hyperplasia with numerous eosinophils. The latter name also reflects some ambiguity of as to whether this is a neoplasm or a reactive process although most experts consider the former. Both Kaposi’s sarcoma, epithelioid hemangioendothelioma, and angiosarcoma would lack the well-formed rounded vessels that is seen in some of this lesion. Although some areas appear Kaposiform, there is the presence of the better formed vasculature that rules out Kaposi’s sarcoma. Similarly, epithelioid hemangioendothelioma is composed of individual cells and cords of cells with cytoplasmic vacuoles yet lacking well-formed vessels. In addition to the architectural pattern that distinguishes it from the various more aggressive mimickers, the lesion lacks cytologic atypia characteristic of angiosarcoma. The presence of the lesion centered around a larger vessel though not always present is characteristic of epithelioid hemangioma. These lesions may recur but metastases do not. These typically occur in the region of the head and neck and the forehead is one of the more common sites.