An unusual presentation of hemophilia B: pseudotumor of proximal tibia.

Hemophilia is one of the most common genetically inherited causes of bleeding disorders. The usual presentation is continuous bleeding from a wound. Very seldom, it presents as a pseudotumor of bone. When left untreated, it may induce compression and pressure necrosis of adjacent structures. Careful evaluation and a high index of suspicion are usually required to arrive at the correct diagnosis. In this article, we report the case of a 10-year-old boy with hemophilia B (Christmas disease) that presented as a pseudotumor producing a large defect in the proximal tibia.