Benign metastasizing leiomyomatosis with massive brachial plexus involvement mimicking neurofibromatosis type 1

We report the case of a patient who presented with right arm and shoulder pain due to compression of the infraclavicular brachial plexus due to benign metastasizing leiomyomatosis (BML). She was initially and had been repeatedly misdiagnosed as having neurofibromatosis type 1 (NF1). The diagnosis of BML was not obvious due to its rare nature, the patient's not detailing the specifics of her gynecologic history of having undergone resection of a large uterine leiomyoma and followed by disseminated pelvic leiomyomatous nodules, histologic misinterpretation of an extrauterine lesion of the spine and the brachial plexus as a neurofibroma and the radiologic diagnosis of lung nodules as being "non-specific" in nature. In addition and importantly, no clinical, radiographic or histologic features of NF1 were present. Although a rare condition, BML should be considered in the differential diagnosis of NF and in patients having a history of uterine leiomyoma. The remarkable, selective involvement of the brachial plexus in this case is unexplained.