Leiomyomas are benign ball-like masses that commonly form in the uterus. Cervical and uterine carcinomas tend to initially form a fairly superficial layer of cancer on the surface of the endocervix or uterine cavity, which may later become deeply infiltrative. Usually, no ball-like mass is produced. Leiomyosarcomas are very rare tumors, which form masses that are usually less regular in geometry than leiomyomas.