Pulmonary benign metastasizing leiomyoma presenting as advanced lung cancer: A case report

Pulmonary benign metastasizing leiomyoma (PBML) is a rare extrauterine smooth muscle neoplasm that predominantly affects women with a history of uterine leiomyoma. Because its clinical and radiological manifestations frequently resemble advanced pulmonary malignancy, establishing the diagnosis remains challenging. Herein, we describe an unusual presentation characterized by a dominant pulmonary mass and diffuse bilateral pulmonary nodules, initially suggesting advanced lung cancer with intrapulmonary metastases.

We report the case of a 38-year-old woman with a previous history of total hysterectomy for symptomatic uterine leiomyomatosis who presented with progressive exertional dyspnea and persistent dry cough. Chest imaging revealed a dominant left lower lobe pulmonary mass associated with numerous bilateral pulmonary nodules, initially raising strong suspicion of advanced lung cancer with intrapulmonary metastases. Extensive microbiological and oncological investigations were unrevealing. Surgical lung biopsy demonstrated benign spindle-cell proliferation without atypia or mitotic activity, while immunohistochemistry confirmed pulmonary benign metastasizing leiomyoma. ^18F-FDG PET/CT excluded hypermetabolic extrapulmonary disease. The patient was managed conservatively with clinical and radiological surveillance and remained clinically stable with symptomatic improvement.

PBML should be considered in the differential diagnosis of women with a history of uterine leiomyoma who present with multiple pulmonary nodules or a dominant pulmonary mass. Histopathological and immunohistochemical confirmation is essential to establish the diagnosis and avoid unnecessary oncologic treatment. Conservative surveillance may represent an appropriate management strategy in selected patients with indolent disease. Given the short follow-up interval in this report, longer prospective surveillance is needed to confirm the durability of this approach.