Benign metastasizing leiomyoma presenting as multiple cystic pulmonary nodules: a case report

Background: Benign metastatic leiomyoma (BML) is an extremely rare disease. Although uterine leiomyomas are benign histologically, they can metastasize to distant sites. While the incidence is very low, the lung is the organ most frequently affected by BML. Pulmonary BML usually presents as numerous well-defined nodules of various sizes, while the cavitary or cystic features in the nodules are rarely observed on radiologic images. Case presentation: A 52-year-old woman complained of cough and dyspnea for one month. She had been previously diagnosed with uterine leiomyoma and had undergone total hysterectomy about 14 years prior. High-resolution computed tomography (CT) images showed that there were multiple cystic nodules of various sizes in both lungs. Pathologic examination revealed that the pulmonary nodule had complex branching glandular structures lined by a single layer of simple cuboidal to columnar epithelium that was surrounded by abundant spindle cells. Additional immunohistochemistry data suggested that pulmonary nodule diagnosis was BML-associated uterine leiomyoma. Conclusion: In this report, we introduce an interesting case of pulmonary BML that presented as a combination of various kinds of nodules including simple round nodules, simple cysts, and cysts with a solid portion, which are very rare radiologic features of BML in lung. In addition, when the patient is a woman of reproductive age, physicians should meticulously review the gynecological history and suspect BML when there are various cystic pulmonary lesions.