Giant Cell Tumour of Bone in a Cat with Extraskeletal Metastases: Pathological and Immunohistochemical Study

Vertebral giant cell tumour of bone in a domestic shorthair cat

Case summary

A 10-year-old male neutered domestic shorthair cat was presented with a 5-month history of progressive non-ambulatory paraparesis. Initial vertebral column radiographs revealed an L2-L3 expansile osteolytic lesion. Spinal MRI showed a well-demarcated, compressive expansile extradural mass lesion affecting the caudal lamina, caudal articular processes and right pedicle of the second lumbar vertebra. The mass was hypointense/isointense on T2-weighted images, isointense on T1-weighted images and had mild homogeneous contrast enhancement after gadolinium administration. MRI of the remaining neuroaxis and CT of the neck, thorax and abdomen with ioversol contrast revealed no additional neoplastic foci. The lesion was removed by en bloc resection via a dorsal L2-L3 laminectomy, including the articular process joints and pedicles. Vertebral stabilisation was performed with titanium screws placed within L1, L2, L3 and L4 pedicles with polymethylmethacrylate cement embedding. Histopathology revealed an osteoproductive neoplasm composed of spindle and multinucleated giant cells without detectable cellular atypia or mitotic activity. On immunohistochemical evaluation, osterix, ionised calcium-binding adaptor molecule 1 and vimentin labelling were observed. Based on the clinical and histological features, a giant cell tumour of bone was considered most likely. Follow-up at 3 and 24 weeks postoperatively demonstrated significant neurological improvement. Postoperative full-body CT at 6 months showed instability of the stabilisation construct but absence of local recurrence or metastasis.

Relevance and novel information

This is the first reported case of a giant cell tumour of bone in the vertebra of a cat. We present the imaging findings, surgical treatment, histopathology, immunohistochemistry and outcome of this rare neoplasm.

Giant Cell Sarcomas in Domestic Rabbits (Oryctolagus cuniculus)

Multinucleated giant cells (MGCs) are a prominent histological feature of various mesenchymal neoplasms and are often considered a criterion of malignancy. Mesenchymal neoplasms with MGCs for which the cell lineage is unclear generally are referred to as giant cell sarcomas. Here we characterize the gross, histologic, and immunohistochemical features of 90 giant cell sarcomas in domestic pet rabbits. Based on the anatomic location and histologic and immunohistochemical findings, 18 cases were classified as histiocytic sarcomas (HS) and 72 cases as anaplastic sarcomas (AS). At postmortem examination, HS was either localized HS (n = 7) always affecting the lungs, or disseminated HS (n = 10) that affected the lungs (n = 10), liver (n = 6), kidneys (n = 4), pleura (n = 2), mediastinum (n = 2), heart (n = 4), skeletal muscle (n = 1), adipose tissue (n = 1), and lymph node (n = 1). Additionally, one cecal biopsy was consistent with HS. Microscopically, HS were characterized by sheets of neoplastic polygonal to round cells that contained single to several, often greatly enlarged nuclei as well as abundant cytoplasm. HS were always positive for CD204 and always negative for SMA and desmin. In contrast, AS arose most commonly from the skin or subcutis (n = 62) and rarely the skeletal muscle (n = 8) or abdominal organs (n = 2). In 29% of extra-abdominal AS, the tumor deeply invaded into surrounding connective tissue, skeletal muscle, tendons, and bone causing pathological fractures. Five of 9 postmortem cases metastasized to various organs often including the lungs. Microscopically, AS were characterized by sheets of spindle or pleomorphic cells admixed with variable numbers of MGCs. Immunohistochemically, AS were always negative for CD204 and often (71%) positive for SMA and/or desmin.

Diagnoses and Clinical Outcomes Associated with Surgically Amputated Feline Digits Submitted to Multiple Veterinary Diagnostic Laboratories

Amputation is commonly performed in an attempt to both treat and diagnose conditions affecting the digits of cats. The records of multiple veterinary diagnostic laboratories were searched to identify submissions of amputated digits from cats. Eighty-five separate submissions were reviewed for diagnosis, age, sex, limb of origin, and digits affected; and the original submitting clinics were surveyed to determine clinical outcome. The Kaplan-Meier product-limit method was used to determine the disease-free interval and survival time. Neoplastic disease was identified in 63 of 85 submissions, with exclusively inflammatory lesions composing the other 22 cases. In 60 (95.2%) of the neoplastic cases, a malignant tumor was identified. Squamous cell carcinoma was the most commonly identified malignant tumor ( n = 15; 23.8%) and was associated with a median survival time of 73 days. Other diagnoses included fibrosarcoma ( n = 14; 22.2%); adenocarcinoma, likely metastases of a primary pulmonary neoplasm ( n = 13; 20.6%); osteosarcoma ( n = 5; 7.9%); mast cell tumor ( n = 4; 6.3%); hemangiosarcoma ( n = 5; 7.9%); malignant fibrous histiocytoma ( n = 2; 3.2%); giant cell tumor of bone ( n = 2; 3.2%); and hemangioma ( n = 2; 3.2%). Giant cell tumor of bone has not been previously described in the digits of cats. Various neoplasms can occur in the digits of cats, and submission of the amputated digit for histopathologic diagnosis is essential to determine the histogenesis and predict the clinical outcome.

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 tumor of bone: a basic science perspective

Comprehending the pathogenesis of giant cell tumor of bone (GCT) is of critical importance for developing novel targeted treatments for this locally-aggressive primary bone tumor. GCT is characterized by the presence of large multinucleated osteoclast-like giant cells distributed amongst mononuclear spindle-like stromal cells and other monocytes. The giant cells are principally responsible for the extensive bone resorption by the tumor. However, the spindle-like stromal cells chiefly direct the pathology of the tumor by recruiting monocytes and promoting their fusion into giant cells. The stromal cells also enhance the resorptive ability of the giant cells. This review encompasses many of the attributes of GCT, including the process of giant cell formation and the mechanisms of bone resorption. The significance of the receptor activator of nuclear factor-κB ligand (RANKL) in the development of GCT and the importance of proteases, including numerous matrix metalloproteinases, are highlighted. The mesenchymal lineage of the stromal cells and the origin of the hematopoietic monocytes are also discussed. Several aspects of GCT that require further understanding, including the etiology of the tumor, the mechanisms of metastases, and the development of an appropriate animal model, are also considered. By exploring the current status of GCT research, this review accentuates the significant progress made in understanding the biology of the tumor, and discusses important areas for future investigation.

Giant Cell Tumor of Bonelike Lesion in a Trp53 Mutant Mouse

Giant cell tumor of bone (GCTB) is a common primary neoplasm of bone characterized by distinctive clinicopathological features. GCTB is exceedingly rare in nonhuman species, and it has been sporadically reported in cats, dogs, rats, and birds. This report describes a primary murine bone tumor that shares striking clinicopathological similarities with human GCTB. The neoplasm occurred in a 71-week-old C57BL/6 mouse heterozygous for the specific Trp53 R172H point mutation. Grossly, the tumor presented as a mono-ostotic nodular mass arising from the distal metaphysis of the right femur. Microscopically, the affected bone was effaced by an osteolytic neoplasm with focal infiltrations into the surrounding tissues. Similarly to what was reported for human GCTB, the murine neoplasm consisted of 3 main cell populations: (1) bundles of pleomorphic spindle-shaped mononuclear cells displaying an indefinite mesenchymal histogenesis with immunohistochemical expression of vimentin and smooth muscle actin, (2) scattered multinucleated giant cells exhibiting osteoclast differentiation with prominent tartrate-resistant acid phosphatase activity and immunoreactivity for monocyte/macrophage markers including CD45 and lysozyme, and (3) scattered round mononuclear cells consistent with activated macrophages and expressing CD45, lysozyme, and F4/80. Based on these morphological and immunohistological results, the murine bone tumor described in this study has been putatively classified as GCTB.

Feline paediatric oncology: retrospective assessment of 233 tumours from cats up to one year (1993 to 2008)

OBJECTIVES

To determine which types of tumour occur in cats up to the age of 12 months based on biopsies submitted to Idexx Laboratories, Wetherby, UK.

METHODS

Retrospective review of histopathological diagnoses of tumours in cats up to the age of 12 months from biopsies received between September 1993 and March 2008.

RESULTS

A total of 4196 submissions from cats 12 months old or younger were identified; 233 biopsies (6%) were neoplastic and fulfilled the search criteria. Tumours were categorised as haematopoietic (n=73, 31%), malignant epithelial (n=44; 19%), malignant mesenchymal (n=38; 16%), benign epithelial (n=37; 16%), benign mesenchymal (n=30, 13%) and miscellaneous (n=11; 5%). The most frequent tumours were lymphoma (n=51; 22%), soft-tissue sarcoma (n=34; 15%), mast cell tumour (n=22; 9%) and squamous cell carcinoma (n=16; 7%). The most common tumour site was the skin and soft tissues (41% of tumours). In all, 164 neoplasms (70%) were malignant or had malignant potential.

CLINICAL SIGNIFICANCE

These data provide unique epidemiological information on a poorly characterised subgroup of feline cancer patients in the UK.

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.