Completely infarcted smooth muscle tumor of the placental membrane.

Non-trophoblastic tumor of the placenta is rare, and so is placental smooth muscle tumor. We report leiomyoma of the placental membrane, which was discovered on cesarean section. Histologically, the tumor was a benign leiomyoma with complete necrosis, and this finding was confirmed immunohistochemically. Only six cases of smooth muscle tumors of the placenta have been reported to date. This is the third report of leiomyoma involving the placental membrane.