Title:Hepatoid-sejtes adenoma és malignus melanoma komponensű kollíziós vegyes bőrdaganat kutyában
SUMMARY The authors described the histopathological, and immunohistochemical investigations of the malignant collision mixed skin tumour, that has been removed surgically from the perianal region of a 11-year-old female Jack Russel Terrier. The tumour was 0.7 × 0.6 mm in diameters, and consisted: (1) melanin-rich malignant melanoma without any signs of lymphovascular invasion, and (2) benign perianal gland adenoma. In the anatomically uniform tumour proximal, 60% (4 mm in diameter) of the total parenchyma was formed by a melanoma, and distal, about 40% of it (3 mm in diameter) was a hepatpoid-gland adenoma. During the immunohistochemical investigations the melanoma showed Melan-A-immunoreactivity, and vimentin-, α-SMA-, panycytokeratin-, claudin-5- and claudin-7-negativities with 38–39% Ki-67 labelling index. The hepatoid-gland adenoma was positive for claudin-5- and claudin-7, and showed vimentin-, α-SMA-, Melan-A-, pancytokeratin-negativities with 0.38% Ki-67 labelling index. In conclusion, this is the first report of a primary cutaneous malignant biphasic collision mixed tumour formed by malignant melanoma, and perianal gland adenoma.