Hemangioendothelioma (HE) refers to a heterogeneous group of vascular tumors with intermediate biologic behavior, between benign hemangiomas and more aggressive angiosarcomas. This summary discusses several HE subtypes: epithelioid hemangioendothelioma (EHE), pseudomyogenic hemangioendothelioma (PHE), and hobnail hemangioendothelioma (HHE). Each of the subtypes of HE have a different risk for metastasis: EHE is the most aggressive, while HHE is the least aggressive. A separate article discusses an additional subtype of HE, kaposiform hemangioendothelioma (KHE), given that it has notable distinct features.

EHE
EHE occurs equally in both sexes and at any age, although it is rarely seen in childhood. This tumor presents as a painful, subcutaneous mass, either superficial or deeper. Lung, liver, and bone may also be primary sites. Approximately half of EHEs are associated with blood vessels. As such, venous occlusion with resultant edema or thrombophlebitis can occur. EHE metastasizes and produces multifocal lesions in around a third of cases with a 15% direct-cause overall lifetime mortality rate.

PHE
PHE (also known as epithelioid sarcoma-like HE) most commonly afflicts male (4:1 predilection) young to middle-aged adults, with a peak incidence at 30 years old.

Classically PHE presents as dermal or subcutaneous nodules on extremities, most commonly on the lower limbs. They occasionally ulcerate. With disease progression, multiple tumor nodules clustered in the same area develop, and many cases present with multifocal lesions. The vast majority of lesions measure less than 3 cm.

Local recurrence after excision occurs in around half of cases, but metastases are rare. The time from excision to local recurrence is generally 1-2 years. The tumor is not generally fatal.

HHE
HHE refers to 2 closely related tumors, retiform and Dabska-type hemangioendothelioma, which both contain cuboidal endothelial cells with a high nuclear / cytoplasmic ratio. These related tumors generally share overlapping features, although they affect different demographics: Dabska-type hemangioendothelioma occurs in children, while the retiform subtype is seen in adults (mean age 40). Both develop as plaques, which are often poorly circumscribed with an overlying violaceous hue. HHEs tend to be low-grade lesions, although they have the potential to extend to regional lymph nodes.