Retroperitoneal Extraskeletal Mesenchymal Chondrosarcoma in a Dog

Abstract

Abstract.A young adult female Mastiff dog developed a large retroperitoneal mass, pleural effusion, and multiple pulmonary and pleural nodules. All masses were diagnosed as mesenchymal subtype chondrosarcomas, using histological and immunohistochemical criteria. Reports of canine extraskeletal mesenchymal chondrosarcomas (EMCs) are rare but involved animals less than 3 years of age in 60% of the cases. This is the first description of this type of tumor developing distant metastases. Evidence from this case and previous reports suggests that EMCs are associated with a poor prognosis.A 20-month-old intact female Mastiff dog presented with a 1-week history of progressive dyspnea, lethargy, and mild weight loss. The dog was alert and responsive, with generalized weakness and mild muscle wasting. A firm, fixed caudal abdominal mass was palpated. Increased lung sounds were auscultated in all fields. Pleural effusion and diffusely scattered, variably sized, pulmonary nodules were visible radiographically. Approximately 1 liter of serosanguineous fluid was drained from the pleural cavity. No neoplastic cells were observed on cytological examination of this fluid, and fungal pneumonia was tentatively diagnosed. An ultrasoundguided fine-needle aspirate of the abdominal mass revealed small numbers of pleomorphic, round-to-oval, occasionally multinucleated cells with basophilic cytoplasm. A malignant mesenchymal tumor was considered most likely, and the dog was euthanatized 8 days after initial presentation.Necropsy revealed a firm white 10-ϫ 8-ϫ 6-cm multilobular retroperitoneal mass. The mass was adjacent, but not adhered, to the fourth, fifth, and sixth lumbar vertebrae near the origin of the left broad ligament of the uterus. Incision of this mass revealed numerous small areas of cavitation that often contained serosanguineous fluid. Approximately 1.5 liters of serosanguineous fluid was present within the pleural cavity. Myriad firm white nodules of up to 1-cm diameter were scattered throughout the lungs. Pleural surfaces were diffusely opaque, and numerous interpleural adhesions were present. No other significant lesions were observed. Tissue samples were fixed in 10% buffered formalin and routinely processed for histological examination. Immunohistochemistry was performed using commercially available antibodies to S-100 protein a vimentin, a desmin, a smooth muscle actin, b and cytokeratin. a The avidin-biotin-peroxidase complex system c was used to visualize all immune reactions.Histological examination of the retroperitoneal mass revealed a pleomorphic proliferation of cells arranged in 2 confluent cellular patterns (Fig. 1). Approximately 30% of the neoplastic cells formed dense sheets supported by a fine fibrovascular network. Cells within these areas were generally small and round-to-oval, with prominent basophilic cen- trally placed nuclei that contained indistinct nucleoli. Cytoplasm was scant and faintly eosinophilic. Cells within the second neoplastic cell pattern were arranged in whorls and bundles. The cel...

Extraskeletal Myxoid Chondrosarcoma with Systemic Metastasis in a Five-Month-Old Irish Setter Dog

“…Our histological, immunohistochemical and ultrastructural findings are similar to those reported previously for extraskeletal myxoid chondrosarcoma in man and other animals [8,17,18]. In dogs, extraskeletal chondrosarcoma occurs in the lung [19], omentum [19], heart including pericardium [1,9,13,19,22], spleen [15], abdomen [20], retroperitoneum [16], and liver [3]. Most previously reported cases involved variants of extraskeletal mesenchymal chondrosarcoma and occurred in adult or old dogs aged 18 months to 17 years (mean 7.8 years).…”

Immunohistochemical and Histopathological Findings of Chondrosarcoma in Mammary Gland of A Dog: A Case Report

“…Primary chondrosarcoma has been reported in appendicular skeleton, synovium, trachea, larynx, lung, liver, subcutaneous, digit, tongue, kidney, abdominal wall, pulmonary artery, omentum, mammary gland, heart and urethra [2][3][4][6][7][8][9][10][11] . In veterinary literature, canine skeletal chondrosarcoma accounts for 1-13% of all chondrosarcomas [1,5] .…”

Chondrosarcoma of the scapula of an 8-month-old Holstein steer

“…3,5,8,10,11,17,18,19,21 The most commonly reported locations in the dog include costochondral junction of the ribs, nasal turbinates, and pelvis, while cartilage of the sternocostal complex (followed by scapula and tuber coxae) is the most commonly identified location in sheep. 1,6,7,12,17,19 Chondrosarcomas in cattle and horses are most often reported in flat bones, but occasionally occur in long bones or extraskeletal locations. 1,3,7,14,[19][20][21][22] In a retrospective study of 67 feline chondrosarcomas, 46 out of 67 cases were associated with bone, with the scapula being the most commonly affected flat bone (15% of all chondrosarcomas arising from the skeleton).…”

“…7,8,18,19 In addition, there are reports of extraskeletal chondrosarcomas in animals, a rare form in which the neoplastic cells exhibit chondroid differentiation, but are present within soft tissue and lack association with the skeletal system. 3,7,9,12,13,15 Most chondrosarcomas in animals are considered primary bone tumors of medullary origin. 8,18,19 Chondrosarcomas tend to arise from any site where normal cartilage exists, and in all species, flat bones are more commonly involved than long bones.…”