History and admission findings: A 45-year-old woman was refferred for diagnosis of an accidentally found symptomless space-occupying lesions in the central part of the right lung. She had undergone a hysterectomy 4 years before and reported smoking 15 cigarettes daily since the age of 17 years. Physical examination was normal.
Investigations: As primary bronchial carcinoma or metastasis to the lung was suspected she underwent a series of diagnostic tests: sonography, computed tomography (CT), gastroscopy, coloscopy, bronchoscopy, skeletal scintigraphy, gynaecological examination and various laboratory tests, none of which indicated a primary extrapulmonary tumour. CT-guided fine-needle biopsy then suggested benign metastasizing pulmonary leiomyoma (BMPL).
Treatment and course: The largest of the tumours were surgically removed, confirming BMPL. Hormone receptors (for oestrogen, progesterone) having been demonstrated, progesterone treatment was initiated as prophylaxis against recurrences. CT 6 months later revealed new intrapulmonary foci. Administration of luteinizing hormone-releasing hormone analog to stop completely any oestrogen effect, and CT of the thorax 6 months later showed that both tumour numbers and their size had been reduced. The patient remained asymptomatic and the findings had not changed in the subsequent 12 months.
Conclusion: BMPL is a rare cause of a space-occupying pulmonary lesion, predominantly affecting middle-aged women after hysterectomy for uterine myoma. The pathogenesis remains unclear, hormone-dependent tumour growth being discussed as a possible mechanism. Anti-oestrogen administration is the treatment of choice to achieve remission and effective prevention of recurrences.