Benign Pulmonary Metastasizing Leiomyoma of Uterus Presenting as Malignancy of Unknown Origin, A Diagnostic Dilemma

Benign metastasizing leiomyoma (BML) is a rare condition characterized by well circumscribed, multiple nodules of smooth muscle cells predominantly involving lungs and other soft tissue organs. Up to 120 cases have been reported since Steiner first did in 1939. It usually affects women of reproductive age with previous hysterectomy for benign leiomyoma. Time interval between initial surgery and development of BML varies significantly with many occurring years after hysterectomy. Most patients are diagnosed incidentally after chest radiograph or computed tomography (CT) scan for other indications. These patients are usually misdiagnosed as malignancy of unknown origin and a delay in obtaining histological diagnosis can cause significant psychological trauma to the patient. Optimum treatment is controversial but hormone manipulation is generally considered the first approach. We report a case of a 54 year old woman with previous hysterectomy who presented with abdominal pain and vomiting. CT scan reported bowel obstruction and multiple lung nodules.