Kaposiform Hemangioendothelioma and Kasabach-Merritt Phenomenon: Management of Coagulopathy and Treatment Options

Abstract

Historically, all localized vascular tumors of infancy and childhood were classified as “hemangiomas,” and any consumptive coagulopathy associated with a vascular anomaly was termed the Kasabach-Merritt phenomenon (KMP). However, with improved understanding of disease pathophysiology and histology, subcategories of vascular tumors are now better defined. Kaposiform hemangioendothelioma (KHE) is a rare vascular tumor with two distinctive features: infiltration across tissue planes and association with the Kasabach-Merritt phenomenon (a syndrome of severe thrombocytopenia, hypofibrinogenemia, and consumptive coagulopathy demonstrated in KHE). Another vascular tumor, tufted angioma (TA), is now considered to be closely related to KHE, likely part of a spectrum of histopathology. KHE presents a diagnostic and therapeutic challenge to the pediatric hematologist oncologist. Invasive interventions including complete surgical excision and vessel embolization were once the mainstay of therapy but placed KHE patients with KMP at great risk of hemorrhagic complications. Numerous pharmacotherapeutic agents with high systemic toxicity including interferon alpha and a variety of chemotherapeutic agents have gradually been replaced by less-toxic agents and more reliably effective agents including combination vincristine/corticosteroid and sirolimus. A multidisciplinary approach to management with an organized and coordinated therapy plan can help achieve best possible outcome for this locally aggressive vascular tumor.