Unusual olecranon mass with ulnar nerve compressive neuropathy caused by a haemophilic pseudotumour.

A 55-year-old man with a history of haemophilia A and bilateral haemophilic arthropathy of the elbows presented with an enlarging left elbow mass and worsening paresthesias in the ulnar distribution of the left hand. The mass, originally thought to be olecranon bursitis and treated as such, was found to be due to a haemophilic pseudotumour. The patient underwent successful excision of the haemophilic pseudotumour with concomitant ulnar nerve decompression and had sustained resolution of the pseudotumour and symptoms at 10 years of follow-up. This case demonstrates the need for consideration of haemophilic pseudotumour in the differential diagnosis for olecranon masses and cubital tunnel compressive neuropathy in patients with haemophilia, and highlights the viability of surgical excision as a therapeutic option for the treatment of haemophilic pseudotumours in the elbow.