Spontaneous hyperplastic and neoplastic lesions of the uterus in mice

A histologic study was done on the spontaneously occurring hyperplastic and neoplastic lesions of the uterus, cervix, and vagina taken from a variety of inbred, hybrid, and backcross female mice. The most commonly observed neoplasm of the endometrium was stromal cell sarcoma, followed by adenocarcinoma, which occurred approximately half as frequently. Hyperplasia was the most commonly observed endometrial lesion occurring either as glandular, stromal, or both and was often cystic with the formation of polyps. Among the benign and malignant lesions other than endometrial, leiomyomas, hemangioendotheliomas and leiomyosarcomas were the most commonly encountered. Lesions in the mucosal cervix and vagina were comparatively rare and were observed in only a few animals. Females with hyperplastic and neoplastic lesions of the uterus, cervix, and vagina in this survey represented a small fraction of the large number of animals necropsied, emphasizing the relative infrequency of these spontaneous lesions in mice.