Ovarian teratoma with a formed lens and nonsuppurative inflammation in an old dog

A 9-year, 7-month-old female German shepherd weighing 26.6 kg was admitted to the hospital for pica and diarrhea. A large mass was found in the right ovary and removed, and cross section of the mass revealed a multilobular tumor consisting of several cystic cavities which contained tufts of dark hair in thick creamy-white sebaceous fluid. Histologically, the tumor consisted of adipose tissue, central nervous tissue, crystalline lens, cartilage and bone. In the central nervous tissue, lens and lesions like nonsuppurative inflammation comprizing of accumulation of glial cells and lymphocytic perivascular cuffing were observed. The tumor was diagnosed as a mature cystic teratoma.