Neonatal Kaposiform Hemangioendothelioma with Kasabach–Merritt Phenomenon Presenting as Severe Airway Obstruction at Birth: A Case Report

<b>Background/Objectives</b>: Kaposiform hemangioendothelioma (KHE) is a rare, locally aggressive vascular tumor of infancy, often complicated by Kasabach-Merritt phenomenon (KMP), a consumptive coagulopathy characterized by severe thrombocytopenia and hypofibrinogenemia. Airway involvement at birth is exceptionally rare and can be life-threatening. This study reports the clinical presentation and treatment course of a full-term male neonate with severe airway obstruction caused by KHE with KMP. <b>Case Presentation</b>: The patient had unremarkable prenatal imaging but presented at birth with severe respiratory distress requiring emergent intubation. Physical examination revealed firm violaceous swelling over the right cervicothoracic region. Laboratory tests showed profound thrombocytopenia (22,000/μL), hypofibrinogenemia (75 mg/dL), and coagulopathy. Imaging findings were consistent with KHE complicated by KMP. Due to bleeding risk, the biopsy was not performed. Initial treatment included platelet and plasma transfusions, intravenous immunoglobulin (IVIG), corticosteroids, and antithrombin III replacement. Vincristine was discontinued owing to gastrointestinal toxicity. Sirolimus therapy was initiated on day 14. Following sirolimus initiation, rapid platelet recovery was observed. At three months, marked tumor regression was documented. After mild recurrence, sirolimus was reintroduced, and the patient remained stable at 16-month follow-up. <b>Conclusions</b>: This case underscores the critical importance of prompt airway stabilization, early recognition of consumptive coagulopathy, and sirolimus-based therapy in managing neonatal KHE with airway involvement.