28283 Efficacy and tolerability of early initiation of sirolimus for kaposiform hemangioendothelioma in an extreme premature infant

Abstract

Kaposiform hemangioendothelioma (KHE) is a rare, locally aggressive vascular tumor most commonly affecting children <6 months of age. It is associated with Kasabach-Merritt phenomenon (KMP), a life-threatening consumptive coagulopathy with severe thrombocytopenia. Although no standard treatment algorithm exists, the mTOR inhibitor sirolimus has proven effective in clinical KHE mass reduction and management of KMP. Literature regarding sirolimus for KHE in children <1 month of age is sparse, with the youngest report to date in an 8-day old term male; long term efficacy and safety continues to be an important area of study. A 26.5 week extreme premature female, born via C-section secondary to maternal hemolysis-elevated liver enzymes-low platelet (HELLP) syndrome, was noted at birth to have a 4.0 × 3.5 cm purpuric, thin expanding plaque over her right upper trunk with ipsilateral hand edema. Punch biopsy was performed; ultrasound was consistent with cutaneous/subcutaneous vascular anomaly. Histopathology showed a vascular proliferation within the dermis/ subcutis, characterized by nodules of spindled endothelial cells (GLUT1-) surrounded by ectatic vascular spaces, degenerated erythrocytes, and CD61+ fibrin thrombi, consistent with KHE. Platelet level decreased from 147 on day of life (DOL) 1 to 51 by DOL 4. Fibrinogen was 244 [170-450] and D-dimer 2,079 [0-500], with a trend to 141 and 1207, respectively, by DOL 6. Sirolimus was started on DOL 6; no platelet transfusion was required. She has remained on drug and stable without adverse event. Blood counts stabilized with remarkable reduction in the size of her tumor.