A degenerating cystic uterine fibroid mimicking an endometrioma on sonography

Uterine fibroids are the most common benign uterine neoplasms, occurring in 20% to 30% of women of reproductive age. Fibroids can be a source of pain, bleeding, and infertility in many women and account for 30% of all hysterectomies performed in the United States. Generally, the sonographic appearance of uterine leiomyomas is characteristic; however, they can undergo various kinds of degeneration that can dramatically change their sonographic appearance and make the diagnosis quite challenging. Here we describe a case of marked cystic degeneration of an exophytic uterine fibroid, which sonographically simulated an endometrioma.