A hemangioma that rapidly increases in size has the potential to trap platelets and cause a consumptive coagulopathy. We describe the case of an 18-week-old boy who was brought to a local emergency department with ecchymosis on his nasal bridge and medial epicanthi, as well as a subconjunctival hemorrhage. He was noted to be anemic and thrombocytopenic. Packed red blood cells and platelets were transfused. However, despite hematologic correction, the ecchymosis and petechiae worsened, and a mass became evident in the right posterior triangle of the patient's neck. Computed tomography demonstrated a lobular soft-tissue-density mass in the right posterior triangle that extended to the level of the skull base. Histologic analysis of a biopsy specimen revealed that the lesion was a giant kaposiform hemangioma. The patient was diagnosed with Kasabach-Merritt syndrome, and prednisolone was commenced as a first-line treatment. However, the mass continued to grow, resulting in inspiratory stridor. Magnetic resonance imaging revealed encroachment into the thecal sac and compression of the spinal cord. The lesion was embolized, and vincristine therapy was commenced. Following a second embolization, the size of the lesion decreased and no further blood products were required. The hemangioma was deemed to be unresectable. The successful treatment in this case was dependent on the maintenance of hemostasis, the initial medical treatment with a corticosteroid, repeat embolization, and longer-term control with vincristine.