Ovarian tumors and related lesions in aged chimpanzees.

The ovaries of a 48-year-old chimpanzee each contained a large bilateral fibrothecoma. A 39-year-old chimpanzee had two small fibrothecomas in one ovary and a well-differentiated Sertoli-Leydig cell tumor in the other; there also was adenomatous hyperplasia of the endometrium. Both animals had extensive thecal hypertrophy in the ovaries. Thecal hypertrophy might have been a source of excessive estrogen and could have been a partial cause of the ovarian tumors.