<p>We describe the case of an 11-year-old boy with hemophilia B who presented with swelling and pain in the left index finger. The patient was referred to our hospital after first presenting to another hospital. The patient experienced slight difficulty making a fist because of limited flexion of the proximal interphalangeal joint. Radiography of the left index finger revealed an expansile remodeling osteolytic lesion with a well-defined sclerotic border and cortical thinning. The patient had prolonged activated partial thromboplastin times and decreased factor IX levels. We performed curettage of the tumor in the left proximal phalanx and artificial bone filling. A hemophilic pseudotumor was diagnosed. At 1&#xa0;year postoperatively, the patient was able to mobilize the index finger without range of motion limitations. Radiography of the left index finger revealed no signs of recurrence. Hemophilic pseudotumor usually occurs in patients with severe hemophilia A; however, this is the first reported case of a hemophilic pseudotumor arising from the finger of a child with mild hemophilia B. When progressive expansile remodeling of bone in the hand of a patient with hemophilia is observed, the possibility of a hemophilic pseudotumor, regardless of the severity or type of hemophilia, should be considered.</p>