Case Report: Pulmonary benign metastasizing leiomyoma diagnosed through clinicopathological correlation

Background Pulmonary benign metastasizing leiomyoma (PBML) is a rare condition characterized by histologically benign smooth-muscle tumors involving the lung, typically in women with a history of uterine leiomyoma. Its radiological features are nonspecific and may overlap with primary pulmonary neoplasms, metastatic malignancies, and other mesenchymal lesions. Diagnosis therefore depends on clinicopathological correlation integrating pulmonary pathological findings with the relevant gynecologic history. Case presentation A 47-year-old woman with a history of uterine leiomyoma underwent evaluation for two right pulmonary nodules detected approximately 6 years and 8 months after uterine myomectomy. Follow-up CT showed stability of the right upper lobe nodule and slight enlargement of the right middle lobe nodule. Thoracoscopic wedge resections were performed for definitive diagnosis. Intraoperative frozen-section examination yielded different provisional interpretations for the two lesions and did not establish a definitive diagnosis. Permanent histopathological examination demonstrated spindle-cell tumors with smooth-muscle differentiation and hormone-receptor expression. Further clarification of the patient's remote gynecologic history, together with the pulmonary morphology and immunophenotype, supported the diagnosis of PBML. At the 1-month postoperative follow-up, no evidence of recurrence was identified, and annual CT surveillance was planned. Conclusion PBML should be considered in the differential diagnosis of pulmonary nodules in women with a current or remote history of uterine leiomyoma. When pulmonary spindle-cell morphology is not diagnostic in isolation, integration of gynecologic history, imaging findings, permanent histopathology, and immunohistochemical findings is important for accurate diagnosis and avoidance of misclassification. This case highlights the value of clinicopathological communication when evaluating pulmonary mesenchymal lesions.