A case of benign metastasizing leiomyoma with multiple metastasis to the soft tissue, skeletal muscle, lung and breast

Abstract

Benign metastasizing leiomyoma (BML) is composed of well-differentiated smooth muscle cells and dense connective tissue. BML affects middle-aged women who have had previous hysterectomies due to a histologically benign-appearing uterine leiomyoma. We report here on a case of BML from the uterine leiomyoma in a 39-year-old woman that involved the soft tissues, skeletal muscles, lungs and breasts. She underwent a hysterectomy for the uterine leiomyoma, double oophorectomy for hormonal ablation and lung wedge resection to confirm the diagnosis. The microscopic findings of the breast and lung tumor were similar to those of the benign uterine leiomyoma. Therefore, we consider that these lesions were breast and pulmonary metastases of the uterine leiomyoma. We report here on a rare case of benign metastasizing uterine leiomyoma that involved the soft tissue, skeletal muscles, lungs and breasts, and we include a review of the relevant literature.

Figure 1

Radiologic findings of benign metastasizing leiomyoma in a 39-year-old woman. The chest radiograph (A) shows multiple, variable-sized nodules in both lungs, suggesting hematogenous metastasis. Chest CT scans with intravenous contrast enhancement demonstrate multiple, well-enhancing masses in the left breast (B, arrow), the left pectoralis minor muscle (C, arrow), and the right infraspinatus muscle (D, arrow). The follow-up chest radiography (E) showed the decreased size of the multiple nodular lesions.

Figure 2

Breast (A, H&E stain ×200) showed nodular proliferation of smooth muscle cells. The tumor shows occasional mitotic activity (4-7/HPF) (B, H&E stain ×400), but no nuclear atypia, hemorrhage or necrosis.