Cytologic findings from a benign giant cell tumor of the tendon sheath in a dog

Abstract

A 6-year-old male neutered Australian Shepherd dog was presented for evaluation of a subcutaneous mass on the plantar aspect of the proximal left metatarsus. Fine-needle aspirate smears contained numerous plump spindle cells and large multinucleated cells amongst a considerable amount of pink extracellular matrix. Histopathologic diagnosis of the tissue obtained during initial biopsy and eventual surgical cytoreduction of the mass was a benign giant cell tumor of the tendon sheath (GCTTS). Immunohistochemically, the synovioblastic neoplastic cells were diffusely strongly positive for vimentin and S-100, were multifocally moderately positive for cytokeratin AE1/3, and were negative for CD18, muscle-specific actin (MSA), and melanoma-associated antigen (mutated) 1 (MUM-1). The dog recovered from surgery and underwent definitive radiation therapy to treat the local residual disease. Eight months later, the mass had not recurred. The diagnosis of GCTTS in this case supports previously published reports describing GCTTS as a relevant disease entity in dogs, and provides the first documentation of cytologic findings with this tumor. Further investigation is needed to correlate pathologic features with clinical behavior and response to therapy in dogs.

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

“…However, when reported, it is more frequently observed in large breed adult dogs and often shows a unilateral presentation similar to that observed in this study; although, a few cases of bilateral presentations have also been reported (MARTI, 1997;CAMPBELL et al, 2014;DEMPSEY et al, 2018). PVNTS affecting the radiocarpal-metacarpal, scapular-humeral, and tibiofibulo-patellar joints, and the sheath of the metatarsal tendon has been reported in dogs; however, involvement of the tarso-tibio-fibular joint has not been previously reported (YOUNG & HUDACEK, 1954;MARTI, 1997;HANSON, 1998;CAMPBELL et al, 2014;DEMPSEY et al, 2018). In this case, the lesion was localized, involving the deep digital flexor tendon in intra-articular presentation and extending to the extra articular region surrounding the tendon.…”

“…in the histological section are reactive macrophages that present receptors for such cytokines (CSF1-R) (WEST et al, 2006). Giant cell tumors of the tendon sheath have been regarded as a rare disease in some studies in veterinary medicine, and there is only one recent report in dogs (CAMPBELL et al, 2014). The characteristic cystic appearance of the mass in this study should be distinguished from that of a synovial cyst, which has similar characteristics.…”

“…Cytopathological examination is frequently used for diagnosis (CAMPBEL et al, 2014) of PVNTS, which is characterized by a population of polygonal or fusiform mononuclear stromal cells associated with multinucleated cells similar to osteoclasts with minimal or no mitotic activity, in addition to macrophages with hemosiderin, which corroborates the diagnosis. Veterinary medicine has limited reports as well as non-specific cytological findings for this disease, as reported by CAMPBELL et al (2014). However, a cystic lesion with macrophages in erythrophagocytic activity, siderophages, and erythrocytes, combined with clinical signs, anatomical location, and radiographic pattern, could be a differential diagnosis of PVNTS.…”

“…In this case, the lesion was localized, involving the deep digital flexor tendon in intra-articular presentation and extending to the extra articular region surrounding the tendon. In humans and horses, the injured and hypertrophied synovial membrane may appear macroscopically as a single nodular structure, commonly appearing localized than diffuse, or it may exhibit several diffuse nodules around the tendon located intra-or extra-articularly (MARTI, 1997;GREENSPAN et al, 2007;CAMPBELL et al, 2014;DEMPSEY et al, 2018).…”

A case of giant cell tumor of soft parts in a horse

“…Giant cell tumor of soft parts is a rare neoplasm, reported in several domestic species, including dogs, cats, and horses. 1,2 In the equine species, it represents one percent of all cutaneous neoplasms. 3 It affects mostly adult animals, with the majority of horses over the age of 10 years.…”