Platelet transfusion recipients occasionally become alloimmunized to foreign HLA and HPA antigens, impairing their responses to further platelet transfusions. Anti-HLA and anti-HPA antibodies, which are produced during pregnancy and blood transfusion, often cause platelet transfusion refractoriness (PTR). We report a case of PTR occurring after platelet transfusion for tooth extraction. A 78-year-old woman was referred to our department because of tooth pain. She had chronic hepatitis and thrombocytopenia, as well as a history of blood transfusion on two occasions. We planned extraction of the left mandibular premolars and left maxillary second molar after the platelet transfusion. After a preoperative platelet transfusion of 20 units was performed, her platelet count decreased. Tests for anti-HLA antibody suggested the possibility of PTR. She had a good response to transfusion of HLA-matched platelets, and the tooth extraction was carried out successfully.
