Mehmet Önder KARAYİĞİT, Mustafa Yavuz GÜLBAHAR, Ahmet ÖZAK, Yonca Betil KABAK, Ayhan GACAR

Oral metastatic melanoma with neurosarcomatous transformation in a dog

Bu çalışmada 16 yaşlı erkek terrier köpekte ön mandibular bölgede sürekli büyüyen, ülserli ve hafif pigmentasyon gösteren tümöral kitle gözlendi. Mikroskobik olarak, tümör iki komponentten oluşmaktaydı. Birincisi epitel benzeri veya iğ şekilli, melanin pigmenti içeren ya da içermeyen hücrelerden oluşan klasik malign melanomdu. İkinci component ise melanin pigmenti içermeyen tipik palisad (Verocay cisimcikleri) ve yalancı-palisadlardan oluşmaktaydı. İmmunohistokimyasal incelmelerde, tümör vimentin, Melan-A, NSE ve GFAP pozitif; HMB45, S100, MBP, desmin, SMA ve pansitokeratin negatifti. Melan-A boyanması klasik melanom alanları ile sınırlıydı. Palisad ve yalancı-palisadlar vimentin, NSE, GFAP için pozitif, diğer antikorlar için negatifti. Lenf yumurusu metastazında doku iğ tarzında hücrelereden oluşmuştu ve vimentin ile Melan-A için pozitifti. Olgu palisad ve yalancı-palisadlarla birlikte nörosarkomatöz farklılaşma gösteren malign oral melanom olarak tanımlandı

Köpekte nörosarkomatöz farklılaşma gösteren oral metastatik melanom olgusu

A 16-year-old male terrier dog was presented with a history of progressively growing ulcerated and slightly pigmented oral masses on the rostral mandible. Microscopically, the tumor composed of two different components. One component was conventional malignant melanoma including epitheloid or spindle-shaped components with/without melanin pigment. The other component was typical palisades (Verocay bodies) and pseudopalisades, with no melanin pigment. Immunohistochemical analysis revealed that the tumor was positive for vimentin, Melan-A, NSE, and GFAP, and negative for HMB45, S100, MBP, desmin, SMA, pan-cytokeratin. Melan-A reactivity was limited to the upper conventional melanoma areas. Nuclear palisading and pseudopalisading structures were positive for vimentin, NSE, GFAP whereas negative for other antibodies. Metastatic lymph node displayed spindle cell melanoma, with immunoreactivity for vimentin and Melan-A. The diagnosis was typical of oral malignant melanoma including nuclear palisading and pseudopalisading components, suggesting neurosarcomatous differentiation in a dog

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