Parasitic and pedunculated leiomyomas: Ultrasonographic features

Leiomyomas are the most common benign uterine tumors. They may be intramural, subserosal, or submucosal in location. Subserosal leiomyomas may be beneath the uterine surface or exophytic or pedunculated. Submucosal leiomyomas may protrude into the uterine cavity and may also become pedunculated. If a pedunculated subserosal leiomyoma develops an extremely long, tenuous stalk, it is called a wandering or migrating leiomyoma. Occasionally, such tumors become adherent to surrounding structures, such as the broad ligament or omentum, develop an auxiliary blood supply, and lose their original attachment to the uterus. They are then called parasitic leiomyomas. Rarely, a parasitic leiomyoma may become torsive and cause an acute abdomen. Pedunculated leiomyomas of the uterus are not uncommon. However, parasitic leiomyomas of the uterus have been described only rarely in the ultrasonographic literature and are seldom discussed in ultrasonography textbooks. We report two patients with parasitic leiomyomas, one of which underwent torsion.