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

Abstract

Kaposiform hemangioendothelioma (KHE) was first described by Zuckerberg et al in 1992.1 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.1, 2 This lesion occurs most commonly over the extremities and other sites such as the head, neck, trunk, and retroperitoneal or thoracic cavity.3, 4 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.2 KHE is commonly associated with Kasabach-Merritt phenomenon (KMP). KMP is triggered by intralesional platelet trapping within a vascular tumor leading to profound thrombocytopenia and consumptive coagulopathy.4, 5, 6 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.1, 3 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 there are several treatment modalities for KHE complicated by KMP, such as corticosteroids, vincristine, intravascular embolization, and surgery. These treatments are described with variable responses and many side effects.7 Recently, sirolimus, a mammalian target of rapamycin inhibitor, was reported to be effective and safe and seems to be a promising agent in treating patients with life-threatening refractory KHE.4, 6, 8 We report for the first time, to our knowledge in the Middle East, a successful outcome using oral sirolimus to treat refractory KHE complicated with KMP in a neonate who did not respond to multiple medical therapies.