Extraskeletal Osteosarcoma of the Mandibular Salivary Gland in a Dog

Abstract

Abstract. A 14-year-old spayed female shepherd/collie crossbred dog had a 6 ϫ 4-cm mass excised from below the right ear. The partially encapsulated, neoplastic mass had a necrotic core and was embedded in the mandibular salivary gland. Histologically, the mass was composed of numerous multinucleate giant cells and large, oval, pleomorphic cells that produced osteoid. Neoplastic cells were immunoreactive for vimentin and actin but not for keratin, desmin, or S-100 protein. At postmortem examination 1 month later, an 11-cm spherical mass had recurred at the surgical site, and there were metastatic nodules in the lungs, ipsilateral mandibular lymph nodes, and kidney. The tumor was diagnosed as an osteosarcoma of the mandibular salivary gland with pulmonary, lymphatic, and renal metastasis. In addition, a 17-year survey of canine salivary-gland neoplasms revealed that most were adenocarcinomas or carcinomas.Key words: Dogs; immunohistochemistry; osteosarcoma; salivary gland neoplasms.Salivary-gland neoplasms and extraskeletal osteosarcomas are both rare in dogs. 3,9,10 Salivary neoplasms make up 0.09% of all canine surgical biopsies in one report. 3 Extraskeletal osteosarcomas have been reported to make up approximately 1% of all canine osteosarcomas. 9 Numerous types of salivary-gland tumors have been reported, as have various classification schemes. 3,5,8,10 One recent review classified tumors as adenocarcinoma, carcinoma, squamous-cell carcinoma, mixed, primary fibrosarcoma, mast-cell tumor, adenoma, and unspecified. 3 Other studies have included mucoepidermoid, acinic cell, malignant mixed, true malignant mixed, malignant melanoma, secondary fibrosarcoma, and secondary lymphosarcoma. 5,8,10,13 Bone has been reported in mixed tumors (pleomorphic adenomas), malignant mixed tumors (carcinoma in pleomorphic adenomas), and true malignant mixed tumors (carcinosarcomas). 2,4,6,13 The vast majority of salivary-gland tumors are adenocarcinomas and carcinomas according to our study and others. 3,10 Extraskeletal osteosarcomas have been reported as primary tumors in a variety of soft tissues, but not in salivary glands. 9 In this paper, we present histopathologic and immunohistochemical evidence of a malignant mandibular salivary-gland tumor that consisted only of an osteosarcoma, and we briefly summarize 43 cases of additional canine salivary-gland tumors.An excisional biopsy was submitted in 10% neutral buffered formalin to the Iowa State University College of Veterinary Medicine, Department of Veterinary Pathology, from a 14-year-old spayed female shepherd/collie crossbred dog. The rapidly growing mass had been known to be present for approximately 2 weeks before being surgically removed. It was described as hard, fixed, encapsulated, vascular, and originating ventral to the right ear and extending under the mandible. Grossly, the surface of the oval mass was light gray, rough, and fibrous, measuring 6 cm long and 4 cm in diameter. A tan, lobulated, glandular structure (mandibular salivary gland) was embedded in the ne...

Thyroid Carcinosarcoma in a Dog

“…Salivary gland was another possibility because osteoid production had been reported in the malignant mixed tumor and extraskeletal osteosarcoma of the salivary gland. 16,19 The IHC results for thyroglobulin confirmed the presence of neoplastic thyroid follicular cells, which were intermixed with vimentin-positive neoplastic mesenchymal cells. One of the previously reported cases of mixed thyroid tumors in dogs was associated with myxedema, 11 whereas the other three did not have any record on this issue.…”

Intermandibular malignant mesenchymoma in a crossbreed dog

“…To the authors’ knowledge, although extraskeletal osteosarcomas have been reported in the trachea, glottis and salivary tissue (Brodey and others 1969, Thomsen and Myers 1999), there have been no previous reports of malignant mesenchymoma arising from the soft tissues of this area. This classification is debatable.…”

“…Such soft tissue sarcomas, showing stromal differentiation down two or more pathways, are presumed to arise from a pluripotential mesenchymal stem cell. No salivary tissue was found within the neoplasm, and immunohistochemical staining for cytokeratin was negative, ruling out malignant mixed tumour of the salivary gland, which can demonstrate osteosarcomatous differentiation (Thomsen and Myers 1999).…”

Osteoclast-like giant cell tumour arising from the kidney in a dog

“…Differentiation of OGCT from an extraskeletal osteosarcoma may be difficult. Less obvious and more localised presence or complete absence of osteoid and bone formation is important distinctive finding (Guccion and Enzinger, 1972;Thomsen and Myers, 1999). A case of extraskeletal canine osteosarcoma that arose from the mandibular salivary gland contained multinucleated giant cells and intensive osteoid and bone formation as well as tumour cells located inside the osteoid lacunas (Thomsen and Myers, 1999).…”