Multiple cutaneous pleomorphic leiomyosarcoma in a dog

A male dog developed multiple cutaneous masses at 15 different sites between the ages of 11.5 and 13-years. The masses were surgically removed and histopathologically examined. In gross appearance, the cut surfaces of the masses were white with partially red areas. Microscopy revealed that the tumors were located at the dermis and were composed of spindle cells and pleomorphic cells with abundant eosinophilic cytoplasm, accompanying giant cells. These cells were occasionally arranged in bundles with minimal stromal collagen. Immunohistochemical analysis revealed that the neoplastic cells were strongly positive for vimentin, partially positive for smooth muscle actin and desmin, and negative for cytokeratin. Based on these pathological findings, the tumor was diagnosed as multiple cutaneous pleomorphic leiomyosarcoma.