Giant hemangioma with thrombocytopenia. Radioisotopic demonstration of platelet sequestration.

T HE ASSOCIATION of thrombocytopenia with giant hemangioma has been documented in approximately 40 cases since the first report of Kasabach and Merritt in 1940. The mechanism of thrombocytopenia is thought to he related to the trapping of platelets by the abnormal endothelium of the tumor, and the accumulation of material presumably derived from the platelets has been demonstrated by histologic technics.3 The actual sequestration of platelets by the tumor should be easy to verify by transfusing platelets labeled with a radioactive isotope, but such studies have produced conflicting results. Petit2 has claimed that no platelet sequestration takes place, and Blix and Aas7 found no increased radioactivity over the tumor following the infusion of tagged platelets. Kontras et al. performed careful studies with baseline calculation of the tumor vascular space followed by infusion of Cr-51 tagged platelets. These authors concluded that the increased radioactivity over the hemangioma should be atrihuted not only to the large blood volume present in the hemangioma hut to an actual trapping of the platelets.6 The present report describes a case of thrombocytopenia associated with giant hemangioma in which similar studies were performed. While our tracer studies are somewhat different from those of Kontras, our isotopic findings, together with the radiotherapeutic results, tend to confirm the occurrence of platelet trapping as reported by these authors.