Gingival Osteogenic Melanoma in Two Dogs

Ellis, Angela E.; Harmon, B. G.; Miller, Debra L.; Northrup, Nicole C.; Latimer, Kenneth S.; Uhl, Elizabeth W.

doi:10.1177/104063871002200133

Cited by 10 publications

(6 citation statements)

References 20 publications

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“…The positive‐staining melanoma reported herein was excised completely and was located in subcutaneous tissue on the right lateral thigh with no bony involvement. Osteoid production has been documented in canine malignant melanomas; osteoid was not visualized in this melanoma, but neoplastic cells may have expressed ALP without evidence of bone formation. Recent studies of melanoma stem‐like cells have shown that subpopulations of these cells express ALP when grown in an osteogenic medium …”

Section: Discussionmentioning

confidence: 78%

Detection of alkaline phosphatase in canine cells previously stained with Wright–Giemsa and its utility in differentiating osteosarcoma from other mesenchymal tumors

Ryseff

Bohn

2012

Veterinary Clinical Pathol

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Section: Discussionmentioning

confidence: 78%

Detection of alkaline phosphatase in canine cells previously stained with Wright–Giemsa and its utility in differentiating osteosarcoma from other mesenchymal tumors

Ryseff

Bohn

2012

Veterinary Clinical Pathol

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“…The presence of significant collagen matrix and spindle cells within collagen fibers, well observed in the fourth biopsy, indicated that neoplastic melanocytes actively produced collagen and osteoid backgrounds within the dense connective tissue. This demonstrated the ability of melanocytes to make mesenchymal elements [5].…”

Section: Discussionmentioning

confidence: 94%

“…Malignant melanoma with bone or cartilage formation has been widely described in humans for more than 30 years, but only few studies on its occurrence in dogs have been reported [5,10,14]. Since then, there have been few or no reports on primary oral melanoma with osteocartilaginous differentiation and metastasis in dogs.…”

Section: Introductionmentioning

confidence: 99%

Canine Oral Osteocartilaginous Malignant Amelanotic Melanoma with Pulmonary Metastasis

Andrade

Silva

Campos

et al. 2018

Acta Scientiae. Vet.

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Background: Melanomas are typically malignant neoplasms commonly observed in the oral cavity of dogs. The classical presentation of melanomas with characteristic melanin pigmentation is easy to diagnose; however, in some cases, the lack of melanin production in the amelanotic oral tumors cause a delay in establishing the precocious diagnosis and consequent treatment. The aim of this report was to evaluate the histopathological and immunohistochemical aspects of an oral amelanotic melanoma with osteocartilaginous formation and metastasis in a dog, in a temporal way.Case: A 10-year-old male German Shepherd dog, presenting mouth bleeding with an amelanotic melanoma located between the upper incisors was received at the Veterinary Hospital of the Catholic University Dom Bosco (UCDB), Campo Grande, MS, Brazil. The animal was clinically evaluated and radiography was performed. The tumor was surgically removed and a sample was collected for histopathological examination that revealed spindloid and some epithelioid morphological cell types surrounded by a fibromatous matrix with moderate amounts of fibrovascular stroma. Approximately 1 month after surgical removal, recovery of the tumor was observed, and a second clinical analysis and collection of sample were performed. These procedures were repeated three times showing the same histopathological characteristics added by myxoid, chondroid, fibromatous tissue, and small groups of chondrocytes as well as central areas of irregular mineralized spicules. X-ray examination revealed proliferative and lytic bone infiltration in the jaw. Immunohistochemical analysis for melanocytic differentiation markers was performed showing positivity to Melan-A, tyrosinase and HMB-45 immunoreactivity, while no S100 reactivity was detected. After 11 months of the first biopsy, pleural effusion and radiopaque disseminated nodules of 1cm in the lungs were detected by X-ray. The animal died and necropsy was conducted. Multiple masses were observed in the lung and at the parietal pleura, suggesting lung metastasis by the positivity for Melan-A.Discussion: The dog was first diagnosed with fibromatous epulis based on the observation of fibroblastic tissue and spindle cells with intense vascularization associated to the site of the tumor and its macroscopic aspect. In the subsequent follow-ups the tumor displayed malignant characteristics observed by recurrence after each surgery, as the tumor returned even larger, aggressive, and infiltrative. From the second biopsy, the histopathological analysis showed the undifferentiated character of epithelioid neoplastic cells, demonstrated by the increase of cartilage and osteoid tissue and the mineral deposit. The phenomenon of the tumor stroma to form cartilage and bone is highlighted here because myxoid change and cartilage formation were frequently observed at the site where amelanotic spindle cells were actively proliferating. It is possible that neoplastic melanocytic cells themselves were involved in the development of the osteocartilaginous areas. Although no cytoplasmic melanin pigmentation was found in the tumor fragments, specific melanocytic markers for melanoma detected neoplastic melanocytes and unmelanized melanosomes. The positive reaction for Melan-A, HMB-45, and tyrosinase in the epithelioid, spindle, and cartilaginous cell groups of the neoplasia indicated amelanotic melanoma with osteocartilaginous differentiation. The negative HMB-45, S100, and tyrosinase expression in lung metastasis may be due to the fact that melanomas express aberrant markers and are also known to display occasional loss of their classic immunophenotype. Amelanotic melanoma can be underdiagnosed due to rapid progression of the tumor allied to the dedifferentiation ability of melanocytes. Thus, the follow up study of cell morphology and immunohistochemical analysis for melanogenic factors can be important determinants in diagnosis.

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“…The extracellular matrix and intracellular eosinophilic granules in this melanoma likely represented foci of cartilaginous differentiation identified histologically. Osteocartilaginous differentiation in these tumors is rare, but has been reported in canine oral melanomas and should be considered when extracellular matrix is observed cytologically. In some cases, neoplastic melanocytes produce matrix, whereas in others its origin is uncertain .…”

Section: Discussionmentioning

confidence: 99%

“…Osteocartilaginous differentiation in these tumors is rare, but has been reported in canine oral melanomas and should be considered when extracellular matrix is observed cytologically. In some cases, neoplastic melanocytes produce matrix, whereas in others its origin is uncertain . Metaplasia of stroma in response to injury or stimulation by neoplastic melanocytes is a proposed mechanism for osteocartilaginous differentiation in these tumors .…”

Section: Discussionmentioning

confidence: 99%