We report a case of hemophilia B in a patient with radicular cyst. A 65-year-old man was referred to our department because of a suspicious circular radiolucent finding in the right maxillary sinus. On further imaging, we found a cystic lesion measuring 32 mm × 30 mm and most likely arising from the apical area of the maxillary right second premolar. Extraction of the cyst and supplementation with coagulation factor were planned. At the time of surgery, we experienced difficulty in achieving hemostasis despite supplementation with coagulation factor, but we were able to stop the bleeding using absorbable oxidized cellulose and fibrin glue as hemostatic agents. Postoperatively, the bleeding recurred and persisted, for which we again administered coagulation factor, and the bleeding stopped completely. Subsequently, no further hemorrhage occurred, and the patient has been followed up for 10 months after surgery.
