Tarsal villonodular tenosynovitis (giant cell tumor of tendon sheath) in a dog

Abstract

A 12-year-old female mixed-breed dog presented with lameness, pain, and an enlarged, non-ulcerated, nodular mass in the region proximal to the tarsal joint of the right pelvic limb. Surgical excision was performed, revealing a 6.5 cm mass adherent to the deep flexor tendon and adjacent tissues. The cut section had cysts filled with blackened clotted material, which exuded reddish serous fluid. Microscopically, the cysts were filled with red blood cells and were either denuded or covered by synoviocytes. In addition, the mass was characterized by marked fibrovascular connective tissue associated with siderophages and multinucleated giant cells. These findings were consistent with those of pigmented villonodular tenosynovitis, a rare condition affecting several animal species and humans.

Imaging features of benign synovial inflammation affecting the long digital extensor tendon sheath in a dog

“…Mimickers of soft tissue neoplasia are widely recognized in the musculoskeletal system and include benign tenosynovial giant cell tumors and pigmented villonodular synovitis 5,11 . There are a a few reports of these masses in the veterinary literature, 5 which share characteristics with the mass in this dog. Giant cell tumors have a genetic association in humans, 11 but in dogs they have been associated with trauma including intra‐osseous hemorrhage 12 .…”

“…Pathology of the LDET and sheath is uncommon in adult dogs, although tendinopathy or rupture secondary to trauma or mechanical injury 1,2 and neoplasia may occur in this region. [3][4][5][6] A relationship between LDET injury with CrCL injury has been postulated. 2 In this case, there was minimal cruciate ligament degeneration on MRI and the dog had a low activity level with no recent history of trauma.…”

“…Pathology of the LDET and sheath is uncommon in adult dogs, although tendinopathy or rupture secondary to trauma or mechanical injury 1,2 and neoplasia may occur in this region 3–6 . A relationship between LDET injury with CrCL injury has been postulated 2 .…”