Capillary‐Lymphatic Malformation, Kaposiform Hemangioendothelioma and Delayed Kasabach‐Merritt Phenomenon

: According to International Society for the Study of Vascular Anomalies classification, vascular anomalies are mainly divided into two groups: vascular tumors and vascular malformations. Nevertheless, a small group of patients present clinical and/or histopathologic overlapping features. We report a case of a 4‐month‐old boy that presented a vascular lesion on his right buttock with involvement of abdominal wall muscles, abdominal cavity and drainage to primitive iliac by a tortuous drainage vein. Surgery was performed and histopathology demonstrated a combined vascular malformation. Six months later he developed a thrombocytopenia and repeat magnetic resonance imaging revealed a new solid mass involving the majority of the abdominal cavity. At 18 months of age the patient developed a Kasabach‐Merrit phenomenon and treatment with vincristine, interferon and then acetyl‐salicilic acid and dypiridamol was started. No response in platelet counts was obtained and one more surgery was perfomed. On this occasion a histopathologic study revealed vascular malformation areas intermingled with areas of kaposiform hemangioendothelioma. This patient demonstrates the Kasabach‐Merritt phenomenon with kaposiform hemangioendothelioma arising within a pre‐existing combined vascular malformation.