Hello mam, inversion uterus is when uterus goes inside down and its inner surface comes out of cervix to protrude from vagina. It can occur due to any tumor arising from the inner surface of uterus which drags the uterine wall along with. This leiomyosarcoma is definitely a matter of concern as it is a serious condition and you should ideally opt for hysterectomy. And further course will depend on biopsy findings. Wish you good health. Take care.