Cutaneous toxoplasmosis in a female Japanese cat.

A 16-year-old female Japanese cat was presented with a single mammary-gland nodule approximately 3 cm in diameter. Histologically, the nodule consisted of necrotizing granulomatous panniculitis, vasculitis, and mastitis, and contained free and clustered protozoal organisms. The organism was present in the cytoplasm of macrophages, fibroblasts, endothelial cells, and mammary-gland epithelia. The organism was positive for anti- Toxoplasma gondii and anti- Neospora caninum antibodies. Electron microscopy showed single and grouped tachyzoites, with morphologic features similar to those of T. gondii. Polymerase chain reaction and deoxyribonucleic acid sequence analysis was consistent with T. gondii infection. This is the first report of cutaneous toxoplasmosis in a Japanese cat.