Kaposiform hemangioendothelioma is a rare, aggressive vascular proliferation in children that is clinically and histologically distinct from hemangioma of infancy. It is often complicated with Kasabach-Merritt syndrome. The authors describe a 2-month-old girl who developed a rapidly enlarging deep subcutaneous solid tumor in the left axilla. The tumor size was about 10x7 cm and there was no skin change over the mass. The results of laboratory tests were significant for a moderate anemia (7.0 g/dL) and a profound thrombocytopenia (3x10/L). The preoperative radiologic findings were suspicious for a soft tissue sarcoma with scapular erosion. Anemia and thrombocytopenia were corrected by preoperative corticosteroid therapy and blood component transfusion. The tumor was excised totally and the pathologic findings were consistent with Kaposiform hemangioendothelioma. Serial blood examinations showed that the hemoglobin and platelet count returned to the normal range after surgery.