Use of Sirolimus in a Premature Neonate With Kaposiform Hemangioedema

Kaposiform hemangioendothelioma (KHE) is a rare, vascular malignancy that is often associated with coagulopathies and thrombocytopenia secondary to platelet trapping. Typically, a person diagnosed with KHE with Kasabach-Merritt phenomenon (KMP) presents with a reddish-purplish lesion, thrombocytopenia, and elevated D-dimer, which can lead to high morbidity and mortality. Sirolimus has been identified as a treatment option for KHE with or without KMP for reduction in lesion size and hematologic parameters. In this case report, a female born at 26.5 weeks was noted at birth to have a purpuric lesion on her right upper back and flank area. She was diagnosed with biopsy-confirmed KHE with KMP. She was started on sirolimus 0.01 mg (0.02 mg/kg; 0.14 mg/m²) once a day, and because of high trough concentrations treatment was held until concentrations decreased. Sirolimus was then microdiluted to a 0.01 mg/mL concentration in medium-chain triglyceride oil for administration. Prior to discharge from the hospital the commercially available product was dispensed for home use. After 6 months of treatment, she achieved a reduction in lesion size and improvement in hematologic parameters, and treatment was stopped at 9 months.