Benign metastasizing leiomyoma (BML) is a rare disorder in which myomatous tissue thought to be of uterine etiology is found in other organs, most commonly lungs and lymphoid tissue. Usually BML is seen after myomectomy and hysterectomy. To our knowledge it has never been reported to present with spontaneous pneumothorax and has not been described after uterine artery embolization (UAE). We report a case of BML presenting as spontaneous pneumothorax 1 year after UAE.
32 yr old African American female who presented to the emergency room with progressive dyspnea and chest tightness of 2 days duration. Past medical history was significant for uterine fibroids for which she had underwent a myomectomy in 1998 and UAE in 2003.A chest x-ray upon presentation showed complete pneumothorax on the left side and multiple small nodules on the right. A CT scan confirmed multiple small nodules, some of which were cavitating. Thoracoscopic biopsies and pleurodesis were performed. Pathology revealed multifocal nodular proliferation of immature smooth muscle cells with formation of subpleural and intraparenchymal cyst-like structures. Our differential diagnosis had included lymphangioleiomyomatosis (LAM) because of the cystic nature of some of the nodules, however stains for HMB 45 were negative, making the diagnosis of LAM unlikely.
BML refers to histologically benign smooth muscle tumors which originate from uterine fibroids. It is a rare disorder with about 100 cases reported in the literature. It is seen exclusively in females. It is associated with a history of uterine fibroids and is more commonly seen in patients who have undergone some form of invasive intervention for their fibroids. Though it has been described in various organs, it is most frequently seen in the pulmonary parenchyma and lymph nodes . BML lesions appear anywhere from 3 months to 20 years after manipulation of the uterine lesion. It is usually an incidental finding as most patients are asymptomatic. However, patients may present with dyspnea, cough or chest pain. Our patient is the first reported case of spontaneous pneumothorax in BML.Radiographically these lesions are well circumscribed solitary or multiple pulmonary nodules ranging in size from a few millimeters to several centimeters in diameter. Typically these nodules are non-calcified and do not enhance with intravenous contrast administration. They may cavitate.Usually there is bronchial and pleural sparring.The exact pathogenesis of BML remains controversial. Multiple theories exist, but vascular dissemination and hematogenous spread during surgical manipulation seems to be the most accepted one. However, there are case reports in which pulmonary nodules have been seen prior to any surgical intervention of the uterine fibroids. Multi-focal origin of the tumor has been advocated to account for this3.Treatment of BML is based on hormonal manipulation as these tumors express estrogen and/ or progesterone receptors. Progesterone treatment has been shown to be successful in regression and prophylaxis against recurrence. Bilateral oopherectomy and parenchymal sparing surgical resection of these lesions are also advocated as treatment modalities. The prognosis of this disease seems to depend on the hormonal receptor status. There are case reports describing regression of tumor during pregnancy and in post menopausal women. We are postulating that the dissemination of myomatous tissue occurred during uterine artery embolization. It is possible that this could have happened during her prior myomectomy. However we do not have any radiographic evidence of this as the patient did not have a chest X-ray performed in the interval.
Dissemination of myomatous tissue may occur with any invasive uterine procedure. UAE is a relatively new modality for treatment of fibroids. Physicians should be aware that BML can present after UAE.
Deepa Lazarous, None.