Sirolimus for treatment of kaposiform hemangioendothelioma associated with Kasabach-Merritt phenomenon

KHE: kaposiform hemangioendothelioma KMP: Kasabach-Merritt phenomenon INTRODUCTION Kaposiform hemangioendothelioma (KHE) was first described by Zuckerberg et al in 1992. KHE is defined as a rare, locally aggressive infiltrative vascular neoplasm that typically occurs during infancy and childhood. KHE generally originates on the skin as a distinctive cutaneous lesion with ill-defined borders, later affecting deeper tissue by infiltrative growth. This lesion occurs most commonly over the extremities and other sites such as the head, neck, trunk, and retroperitoneal or thoracic cavity. According to a previous case series at a large referral center, the incidence of KHE is estimated at 0.07 per 100,000 children per year. KHE is commonly associated with KasabachMerritt phenomenon (KMP). KMP is triggered by intralesional platelet trapping within a vascular tumor leading to profound thrombocytopenia and consumptive coagulopathy. KHE is associated with a relatively high mortality rate (around 30%). However, deaths are almost always related to local invasion and compression of vital structures or are a result of KMP. To date, it is particularly challenging to treat KHE complicated by KMP, as no controlled trials have been conducted to describe variable responses of the therapeutic options for this relatively rare neoplasm. According to the consensus-derived practice standards plan for complicated KHE published in 2013