Comparison of tyrosinase-related protein-2, S-100, and Melan A immunoreactivity in canine amelanotic melanomas.
Tyrosinase-related protein-2 (TRP-2) is a highly conserved melanogenic enzyme expressed in both pigmented and unpigmented melanomas of the mouse. To determine whether TRP-2 would be a good diagnostic marker for amelanotic melanomas of the dog, we performed immunohistochemistry for TRP-2, S-100, and Melan A on 21 canine tumors identified as amelanotic melanomas based on routine histopathologic examination. Thirteen of the tumors were TRP-2 positive, 10 were Melan A positive, and 19 were S-100 positive. TRP-2 was expressed in the cytoplasm of tumor cells in both primary and metastatic melanomas. S-100 staining was positive in all of three schwannomas and two of three gastrointestinal stromal tumors (one fibrosarcoma and one leiomyosarcoma) tested. Neither Melan A nor TRP-2 antibodies reacted with these tumors. Our findings indicate that staining for TRP-2 is a sensitive and specific method for confirming the diagnosis of amelanotic melanoma in dogs.
Choi
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Department of Veterinary Biosciences, The Ohio State University, 1925 Coffey Road, Columbus, OH 43210, USA.
Kusewitt
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D000818:Animals; D000951:Antigens, Neoplasm; D004283:Dog Diseases / Q000276:immunology*; D004285:Dogs; D007150:Immunohistochemistry; D019746:Intramolecular Oxidoreductases / Q000276:immunology*; D058965:MART-1 Antigen; D018328:Melanoma, Amelanotic / Q000276:immunology / Q000662:veterinary*; D009363:Neoplasm Proteins / Q000276:immunology*; D009418:S100 Proteins / Q000276:immunology*; D012680:Sensitivity and Specificity; D012878:Skin Neoplasms / Q000276:immunology / Q000662:veterinary*
D000951:Antigens, Neoplasm; D058965:MART-1 Antigen; C548668:Mlana protein, mouse; D009363:Neoplasm Proteins; D009418:S100 Proteins; D019746:Intramolecular Oxidoreductases; C042501:dopachrome isomerase