Today’s case is a 12 year old male neutered Great Pyrenee. Forelimb lameness. What is your interpretation?
Baseline left humerus: There is a mixed osteolytic and osteoproductive lesion in the proximal left humerus. There is an area of geographic lysis caudally, and increased opacity from the surrounding proliferative bone.
Post radiation therapy: The areas of proliferative bone surrounding the proximal humerus and extending to the soft tissues caudally have increased in opacity. There are additional areas of lysis in the proximal humerus compared to the previous exam. The area of the osteosarcoma lesion is also greater than previously seen.
The aggressive bone lesion in the proximal left humerus is most consistent with a primary bone tumor such as osteosarcoma.
Osteosarcoma. Palliative radiation therapy was performed between the first and second set of images.