Giant cell tumor of the bone in a scarlet macaw (Ara macao).

A 6-mo-old female scarlet macaw (Ara macao) was presented after a 2-mo period of anorexia and weakness. The bird was reluctant to fly 1 wk before referral due to a painful left wing. Physical examination revealed a firm swelling around the left shoulder. On radiographs, the diaphysis and proximal metaphysis of the left scapula were radiolucent. Computer tomography revealed an osteolytic process, suggestive of a bone tumor, affecting the left scapula. Cytology of a fine needle aspiration biopsy of the mass showed erythrocytes, a proliferation of spindle-shaped mesenchymal cells, and multinucleated giant cells (osteoclasts) suggestive of a giant cell tumor. The left wing, including the scapula, was amputated. The bird showed a fast recovery but died 1 hr later. Findings during the pathological examination were compatible with shock due to blood loss. The shoulder process was characterized as a giant cell tumor. To our knowledge, this is the first complete report of a giant cell tumor of the bone in a bird.

Clinical, histological and prognostic features of a novel nail-bed lesion of cats: 41 cases.

Objectives There is a distinct subset of lesions arising on the digits of cats, located at or close to the nail-bed epithelium, which are typically composed of proliferative fibroblast-like cells, multinucleate giant cells and areas of osseous metaplasia, but currently there is no published literature detailing the clinical or histological features of these lesions. Methods This study identified 41 such cases from two large commercial diagnostic laboratories and assessed various histological and clinical features; 22 cases had additional follow-up data available. Results All masses in this study were exophytic, variably inflamed, contained large numbers of spindle cells and had areas of capillary formation. The majority also had areas of ulceration, multinucleate giant cells and osseous metaplasia. The mitotic count was variable, but mitoses were confined to the fibroblast-like cells. Male cats appeared predisposed and the second digit was the most commonly affected. Conclusions and relevance These distinctive lesions arising on the digits of cats had potential for local recurrence but metastasis was not reported. Based on these clinical and histological features, the masses in this study appear most similar to giant cell reparative granulomas, and trauma, injury to the nail or nail-bed and nail-bed infections may potentially contribute to their development.

Giant cell tumour of bone in a cat.

A domestic shorthaired cat had a firm, non-painful swelling of the left antebrachium. Radiographs showed an expansile, multiloculated lesion in the radius. The mass gradually enlarged over the following four and a half months and the animal became completely lame. The histological diagnosis was giant cell tumour of bone; this is a rare neoplasm of bone in veterinary patients. Giant cell tumour of bone should be considered in the differential diagnosis of bone lesions having an expansile, multiloculated radiographic appearance.

Protease expression in giant cell tumour of bone: a comparative study on feline and human samples.

Human giant cell tumour of bone (GCTB) is a rare low grade of malignancy tumour with tendency to recur. During tumourigenesis the bone remodeling balance is subverted by the tumour cellular components that interacting with bone matrix induce release of growth factors and cytokines, promoting cell proliferation and bone resorption. The master regulators of this positive feed-back are acid and neutral proteases that destroying extracellular matrix increase osteolysis. In contrast, in cats, very few data are reported on GCTB biological activity. In this study, histological features and metalloproteinase (MMPs) and urokinase plasminogen activator system (uPA) expression were compared in human and feline GCTB and differences in distribution and intensity related to histological pattern and clinical behaviour were determined. In both species, the overexpression of these molecules suggested a strong and complex cross-talk between tumour and microenvironment.

Giant cell osteosarcoma in the calvarium of a cat.

Feline primary osteosarcomas involving the skull are extremely rare. When they occur, orbit, mandible, and maxilla are the most common sites. Microscopically, scattered multinucleated giant cells (MGCs) are not an uncommon occurrence in osteosarcoma (OSC), but they are generally in low number. Only in a rare variant, the giant cell-rich OSC, are MGCs the prevalent cell type. Although osteoclast and osteoblast origin have been postulated in human and veterinary literature, the origin of MGCs in osteosarcomas is poorly understood. This report describes a giant cell-rich OSC in the calvarium of a 13-year-old spayed female shorthair cat. The animal exhibited a range of neurologic signs, including left circling, compulsive gait, lack of proprioception, and bilateral absence of menace reaction, with indication of left forebrain involvement. Gross lesions were characterized by a multilobate, spherical mass located in the left calvarium, compressing the left forebrain. Histologically, the tumor was characterized by scattered nests of MGCs separated by small bundles of pleomorphic, fusate to polygonal cells. Between spindle cells, osteoid was very sparse and arranged in thin strands. Immunohistochemical stains for vimentin were positive, with no detectable cellular staining for cytokeratin, S-100 protein, or Class II major histocompatibility complex. Ultrastructurally, MGCs contained profiles of rough endoplasmic reticulum; no lysosomes were observed. The origin of MGCs in osteosarcoma remains obscure, and our results confirm their ambiguous identity.

Giant cell tumour of bone in a cat with extraskeletal metastases: pathological and immunohistochemical study.

A case of giant cell tumour of bone (GCTb) in the lung and in a subcutaneous mass located in the right flank, with a probable primary origin in the mid-diaphysis of the right tibia, was described in a 8-year-old female cat. Numerous multinucleated giant cells were homogeneously distributed among a population of ovoid or spindle-shaped mononuclear cells. All of them were positive for vimentin suggesting a mesenchymal origin. Spindle-shaped tumour cells resemble fibroblastic cells, showing collagen fibres in their vicinity. Ovoid mononuclear cells are similar to macrophages, with a cytoplasm rich in electron-dense lysosomes. Multinucleated giant cells appear morphologically similar to osteoclasts. These findings are supported for the positive reaction to tartrate-resistant acid phosphatase (TRAP) and lysozyme, encountered only in ovoid and multinucleated giant cells. No immunoreactivity against human oestrogen receptors was observed in the nuclei of any neoplastic cells.