Intraosseous lipoma in the ulna and radius of a two-year-old Leonberger.

This report describes a case of intraosseous lipoma in a two-year-old Leonberger. The dog was presented with a history of ten month lameness in the right forelimb. A massive swelling from the elbow to the carpus of the right forelimb was visible. Treatment with anti-inflammatory medications by the local veterinarian for ten months was unsuccessful and the dog was presented at the university clinic. Radiographic images showed that the diaphyseal part of the ulna was affected by extensive cyst-like osteolysis. Furthermore, the distal metaphysis of the radius showed cyst-like osteolytic changes. The soft-tissue mass and parts of the ulna periosteum were surgically resected. Histopathological analysis of the mass in combination with clinical, surgical and radiographic findings was diagnostic for an intraosseous lipoma. The dog had a good long-term outcome as it was free of any signs of recurrence at the follow-up examinations performed after 18 months and after five years. To the authors' knowledge, this is the first description of intraosseous lipoma in a dog.