This week’s case is a 4-year-old female Yorkshire Terrier with a 2-year history of toe swelling with previous P2 amputation. For musculoskeletal cases, my first priority is to decide whether the lesion is aggressive or non-aggressive. What do you think?
On radiographs of the left pelvic limb, there is lysis of the second metatarsal bone with only a proximal remnant. The third digit, including P1-2 and the distal metatarsal bone, are also lytic. The regions surrounding the distal interphalangeal joint of P5 are also lytic. P4 appears intact. There are small fragments of soft tissue in the region of the lytic metatarsal bones. The soft tissues surrounding this region are thickened, and there is smooth periosteal reaction and sclerosis of the third and fourth metatarsal bones.
Severe multifocal aggressive bone lesions with osteolysis in the distal left pelvic metatarsal and phalangeal regions. This is most likely due to osteomyelitis; however, a soft tissue neoplasm invading bone cannot be completely ruled out.
The digits were amputated and osteomyelitis was found in P3, with resorption and fibrous replacement of bone in P5. No organisms were isolated.