Benign metastasizing leiomyoma of the lung: A case report and literature review

Abstract

Pulmonary benign metastasizing leiomyoma (BML) is a rare event characterized by benign soft-tissue tumors that occur when uterine leiomyomas metastasize to the lung. The present study reports the case of a 47-year-old female patient who presented with multiple bilateral pulmonary nodules on a chest X-ray during a health checkup nine years after a hysterectomy due to uterine fibroids. Chest computed tomography (CT) revealed multiple well-defined nodular shadows in the lung. One tumor of the left upper lung was resected by thoracoscopic surgery. Pathologically, the resected lesion consisted of benign spindle cells and was diagnosed as BML. The post-operative course was uneventful. Other lung nodules have been meticulously monitored at follow-up, and repeat CT two years later showed that these nodules had not increased at all in size and that no new lobe nodules had appeared. The present study indicates that pulmonary BML occurs in a low proportion of female with a history of uterine leiomyoma and treatment methods for it are diverse and controversial.

Keywords: benign metastasizing leiomyoma; pulmonary nodules.

Figure 1.

Computed tomography scans showing generally smooth and diffusely distributed lesions in each lung.

Figure 2.

Positron emission tomography-computed tomography results revealing multiple hypometabolic masses in the lungs.

Figure 3.

Low-grade spindle cell proliferation in the excised lesions from the left upper lung lobe. (A) Benign metastasizing leiomyoma (BML) in the lung with entrapped bronchoalveolar epithelium (hematoxylin and eosin staining, x10 magnification). (B) BML in the lung showing benign-appearing spindle-shaped cells arranged in intersecting fascicles (hematoxylin and eosin staining, x40 magnification).

Figure 4.

Immunohistochemical staining of benign metastasizing leiomyoma (BML). BML in the lung showing positivity for (A) actin, (B) desmin and (C) smooth muscle actin, with entrapped bronchoalveolar epithelium showing positivity for (D) cytokeratin 7, (E) surfactant protein A and (F) thyroid transcription factor 1.

Figure 5.

Repeated computed tomography scan at 2 years post-diagnosis. The existing nodules have remained stable and no new nodules can be observed.