Kaposiform hemangioendothelioma (KHE) is a rare congenital vascular tumor. Most cases occur in infancy, especially in the neonatal period. KHE may arise in childhood or rarely in young adults. In the skin, KHE presents as a solitary violaceous plaque, nodule, or tumor of variable size. KHE arises most frequently on the extremities, though head, neck, and trunk may also be primary sites. KHE may also extend to involve bone, the mediastinum, or the retroperitoneal space.

KHE spreads locally, but no cases of distant metastases have been reported. It is 1 of 2 vascular tumors that have been strongly associated with the Kasabach-Merritt phenomenon (KMP), the other being a tufted angioma, where a thrombocytopenia and, less frequently, a consumptive coagulopathy develop in the setting of a rapidly enlarging tumor. KMP is thought to occur as a result of platelet trapping and subsequent consumption of clotting factors within the tumor. KMP is a life-threatening complication. In the presence of KMP, rapid growth of the KHE occurs and purpura overlying the tumor and an ecchymotic edge may be seen. More general bruising or bleeding also may be seen. Acute distress due to hemothorax, intracranial, or intra-abdominal bleed may occur, as may high output cardiac failure.

Larger tumors that involve more than one anatomic region, and deeper tumors that involve muscle or bone, have been associated with a higher risk of KMP. KMP is rarely seen in KHE that develop in older children or adults. Overall, KMP develops in around 70% of KHE tumors.

Related topic: hemangioendothelioma