Odontogenic Myxoma in an 8-Year-Old Labrador Retriever Dog

Abstract

Abstract. Odontogenic myxoma (OM) was diagnosed in an 8-year-old Labrador Retriever dog with an ulcerohemorrhagic mass located on the caudal area of the right maxillary gingiva. The neoplasm was characterized by a low mitotic index and moderate numbers of spindle, stellate, and round cells that were sparsely distributed in an alcian blue reactive myxomatous matrix. Individual neoplastic cells were characterized by small amounts of faintly eosinophilic staining cytoplasm, prominent nucleoli, and stippled amphophilic staining chromatin that was immunoreactive for vimentin but negative for cytokeratin and actin. To the authors' knowledge, this is the first reported case of canine OM from North America, and it shares histomorphologic and histochemical features with 3 other cases reported in dogs elsewhere. Whereas, a literature review suggests untreated canine OM is insidious and locally aggressive, the prognosis in the present dog remains unknown. These findings support previous recommendations for inclusion of canine OM on the World Health Organization list of odontogenic tumors.

Odontogenic Fibromyxoma in a Cat: First Confirmed Case in This Species

“…Other than the nonspecific mention of a canine OM in 1963, 34 all other canine reports have occurred since 2005 (Table 1). 32,37,40,41 As veterinary dentists and pathologists continue to refine our histopathological classifications of oral tumors, as new techniques in pathology and surgery become available, as digital information grows increasingly accessible, and as higher levels of pet care are sought out, perhaps the reported prevalence will change.…”

“…2 In the 4 reported cases of canine OM and for the single case report of a nonhuman primate, metastasis to the lungs or regional lymph nodes was not mentioned. 32,36,37,40,41 Two of the 4 canine cases noted local recurrence of the OM. 37,41 In 1 case, the surgery and time until recurrence were not described.…”

“…2 Vimentin is a 58-kD protein present in mesenchymal cells. 39,40 Studies have found that human OMs test positive for vimentin and smooth-muscle actin. 39 Two of the reported canine OMs underwent immunohistochemical evaluation.…”

“…Table 1 summarizes the current literature regarding veterinary OM. The tumor has been reported in a 3-year-old Jack Russell terrier, 32 an 8-year-old Labrador retriever, 40 a 12-year-old Doberman pinscher, 37 a 14-year-old dachshund, 41 a nonhuman primate ( Macaca mulatta ), 36 horses, 22,31 and cattle. 22 A 1963 report classifying odontogenic tumors in man and animals cites a review of 1230 oral tumors in which only 1 OM was diagnosed.…”

Conjunctival myxoma in a dog: clinical and histopathological features

“…Myxomas are rare tumours derived from primitive mesenchymal cells and are characterised by a large amount of mucin in the intercellular matrix. These benign, slow‐growing neoplasms can occur at any site where there is connective tissue, but they more frequently affect joint tissue (synovial myxoma), heart, and teeth (odontogenic) . To the best of the authors’ knowledge, no reports of myxomas involving the eye in any canine species have been published to date in the veterinary literature.…”