A 14-year-old, spayed female, Maltese with multiple nodular skin lesions was presented to a local animal hospital. The nodules were infiltrated by discrete round to polygonal neoplastic cells with large nuclei. Cells having phagocytic activities and multinucleated cells were also present. Immunohistochemically, neoplastic cells were positive for vimentin, S100, lysozyme and CD18 and negative for pancytokeratin, CD3, CD79α, and CD138. Considering histopathologic and immunohistochemical features, the tumor was diagnosed as disseminated cutaneous hemophagocytichistiocytic sarcoma. This is the first report of this disease in a Maltese dog.

Key words: CD18, Dogs, Histiocytic sarcoma, Immunohistochemistry, Neoplasms