Paraneoplastic ocular proptosis secondary to a pulmonary benign metastasizing leiomyoma: a case report and brief literature review

Paraneoplastic syndromes are indirect clinical manifestations of cancer, arising from immunological mechanisms or tumor-derived substances. The most common paraneoplastic syndromes associated with lung cancer are endocrine syndromes. We report the case of a 50- year-old woman with progressive ocular proptosis and orbital pain who was evaluated by multiple specialties with various diagnostic tests that did not explain her symptoms. She received immunosuppressive therapy without clinical improvement. A right paracardiac mass was subsequently identified on imaging, initially suspected to be a pericardial cyst, but prior studies over 3 years showed significant interval growth. The lesion was resected via thoracoscopic surgery, and the patient showed symptomatic improvement within a few days. Pathological results revealed a benign metastasizing leiomyoma. Given clinical presentation and postoperative evolution, a paraneoplastic mechanism is considered the most likely cause of the patient's ocular proptosis.