Localized primary cutaneous intravascular papillary endothelial hyperplasia.

A 10-year-old boy developed an asymptomatic, pigmented, flat-topped papule on the thigh. Biopsy revealed intravascular papillary endothelial hyperplasia in a dilated capillary of the superficial dermal plexus. This vascular abnormality was not accompanied by demonstrable thrombotic material or by angioma. Pathogenetically, intravascular papillary endothelial hyperplasia in this case appears to represent a primary rather than a reactive endothelial proliferation.