Benign metastasizing leiomyoma in femur and thigh with a history of uterine leiomyoma: A case report and literature review

Benign metastasizing leiomyoma (BML) is a rare disease that is characterized by well-differentiated smooth muscle tumors occurring extrauterine site in women with a history of uterine leiomyoma. The lung is the most common metastatic site for BML. A 48-year-old woman, who had histories of laparoscopic myomectomy and transabdominal total hysterectomy, visited an orthopedics complaining of a mass in her left thigh and difficulty in walking. Magnetic resonance imaging (MRI) and fluorine 18 fluorodeoxyglucose positron emission tomography/computed tomography revealed multiple mass lesions in her both thighs and left femur as well as both lungs. She was referred to our hospital for further examination. We diagnosed her tumors as BML according to histopathological analysis of tumor specimen. The left thigh tumor was resected and the treatment with gonadotropin releasing hormone agonist regressed the size of the residual tumors by approximately 30%. BML should be considered when multiple soft tissue tumors are found in women with a history of leiomyomas.