Limb salvage in Christmas disease masquerading as fungating aneurysmal bone cyst.

A boy in middle childhood presented with complaints of swelling and pain in his right forearm for 4 months. He had previously undergone left above-elbow amputation due to a suspected malignant tumour in that arm. Radiological imaging revealed a locally aggressive bone tumour of the right distal radius. Two biopsies failed to provide a diagnosis, and in the meantime the lesion became fungating. Consequently, it was decided to perform wide resection together with wrist arthrodesis. Postoperatively, on day 4, the patient developed wound dehiscence and impending compartment syndrome. During revision surgery, a significant quantity of blood clots was removed, without any active bleeders. Due to the uncertain diagnosis, thromboelastography (TEG) analysis was done, which showed a fibrinolytic pattern, and the patient's factor IX level was found to be 4% of the normal value. As a result, a diagnosis of haemophilia B was established. The patient was started on tranexamic acid and factor IX replacement therapy.