PIGMENTED VILLONODULAR SYNOVITIS IN A RETICULATED GIRAFFE (GIRAFFA CAMELOPARDALIS)

Abstract

: A 17-yr-old, female, captive-born reticulated giraffe ( Giraffa camelopardalis ) presented with acute-onset lameness of the right metacarpophalangeal (fetlock) joint. Despite multiple courses of treatment, the lameness and swelling progressively worsened over a 3.5-yr period, and the giraffe was euthanized. At necropsy, gross and microscopic changes in the right, front fetlock and associated flexor tendon sheath included villous synovial hyperplasia and the formation of discrete pigmented nodules within synovial membranes. Histologically, the nodules were composed of abundant, fibrous connective tissue with heavy macrophage infiltration, hemosiderin deposition, and distinctive, multinucleated cells that resembled osteoclasts. These findings were consistent with pigmented villonodular synovitis (PVNS), a rare condition affecting both humans and animals. Although the pathophysiology of PVNS is poorly understood, lesions exhibit features of both neoplastic and reactive inflammatory processes. This case report represents, to the authors' knowledge, the first description of PVNS in a nondomestic ungulate.

Chronic lymphoplasmacytic villonodular proliferative synovitis in a 10-year-old Jack Russell Terrier dog

“…Furthermore, the sero-sanguineous appearance of joint fluid and the reddish-brown discolouration of the synovial membrane reported in this study has also been described in cases of villonodular synovitis by other studies [6,8,16]. The negative culture, high cellularity, mitotic figures, appearance of red blood cells, mild nucleated neutrophilia and abnormal mononuclear cells on microscopy and the proteinaceous precipitation of the joint fluid [1,28,34], though not pathognomonic for CLPVNS, is suggestive of the condition.…”

“…When chronic and associated with plasma cell and/or lymphocyte infiltrates, the condition is known as chronic lymphoplasmacytic villonodular proliferative synovitis (CLPVNS) [8,9]. CLPVNS has been described in humans [6,[9][10][11], dogs [1,3,[12][13][14][15], horses [8] and giraffe [16].…”

“…The aetiology of villonodular synovitis (VS) is uncertain [6,12,14]. Degenerative [1,2,19,21,22], immunopathological [3,23], reactive inflammatory [6,15], neoplastic mechanisms [11,24] or both neoplastic and reactive inflammatory mechanisms [16] have been suggested as possible causes.…”

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

“…With respect to the immunohistochemical aspect of PVNTS, the panCK antibody was used to discard epithelial cells on the surface of the cysts and confirmed the synovial origin with the morphological aspects, in addition to excluding epithelioid components characteristic of the subtypes of synovial cell sarcoma (CRAIG et al, 2002;POOL & THOMPSON, 2002). The immunoreactivity patterns observed in this study were similar to those described by other authors (MALATESTA et al, 2005;IHMS et al, 2017) in a lynx and giraffe, with strong and diffuse immunolabeling for vimentin, suggestive of the collagenous origin of the stroma and negative results for panCK. The multifocal and discrete cytoplasmic labeling for the Iba-1 antibody suggests that mononuclear and multinucleated cells represent activated monocytic cells (WEST et al, 2006;IHMS et al, 2017).…”

“…The nature of PVNTS is controversial, given its morphological characteristics and clinical behavior, indicative of both inflammatory and neoplastic lesions. The debate regarding its etiology is still ongoing (IHMS et al, 2017). However, based on recent canine studies, the term PVNTS was chosen by the authors in this research (AKERBLOM & SJÖSTRÖM, 2006;DEMPSEY et al, 2018).…”