Pulmonary benign metastasizing leiomyoma with limited tumor response to apatinib combined with hormonal therapy: a case report

Background Pulmonary benign metastasizing leiomyoma (PBML) is a rare disease characterized by extrauterine dissemination of benign smooth muscle tumors, most commonly to the lungs. The typical immunophenotype shows positivity for smooth muscle markers (desmin, SMA) and hormone receptors (ER, PR), while CD34 is usually negative in tumor cells. Current management options include hormonal therapy, surgical resection, and watchful waiting, but no standardized treatment protocol exists. The role of antiangiogenic therapy in PBML is unexplored. Case description A 48-year-old premenopausal woman with a history of hysterectomy for uterine leiomyoma presented with multiple bilateral pulmonary nodules. Lung biopsy revealed a spindle cell tumor with immunohistochemistry positive for desmin, SMA, ER, PR; CD34 staining was positive in vascular endothelial cells but negative in tumor cells. Given the high tumor burden, and after thorough discussion, the patient received leuprorelin, tamoxifen, and the antiangiogenic agent apatinib as an exploratory attempt. Post-treatment imaging showed stable disease (SD) according to RECIST criteria. After 16 months, apatinib was discontinued due to hypertension and proteinuria, but stable disease persisted. After more than five years of follow-up (including continued tamoxifen monotherapy after menopause), the pulmonary nodules have remained stable without significant shrinkage. Conclusions This case documents a PBML patient with long-term follow-up and represents the first report of apatinib combined with hormonal therapy in PBML. Long-term disease stability occurred during endocrine therapy; however, the relative contributions of treatment and the natural history of PBML cannot be determined from this single case. No clear incremental benefit of apatinib could be demonstrated; however, the absence of significant tumor shrinkage does not establish a lack of therapeutic activity. The findings should be considered inconclusive regarding apatinib efficacy, and the role of antiangiogenic therapy in PBML remains uncertain.