A giant plexiform schwannoma of the brachial plexus: case report

Plexiform Schwannoma is a rare variant of Schwannoma that accounts for only 5% of all Schwannomas, which typically shows a plexiform or multinodular growth pattern mimics plexiform neurofibroma. It was first described by Harkin and Reed in 1978 [1]. Plexiform Schwannoma usually develops in the dermis or subcutaneous tissue, and it is uncommon for the Schwannoma to develop in deep-seated nerves. Its histological features include Antoni A and B areas, diffuse and strong positivity with immunohistochemical markers like S-100, laminin and collagen type IV.On the other hand, plexiform neurofibroma lacks Antoni A and B areas of schwannoma and shows weak S-100 positivity. Plexiform schwannoma shows up to 5% association with neurofibromatosis-2 and schwannomatosis, but has no association with neurofibromatosis-1 like plexiform neurofibroma [2,3]. This report describes the rare case of a giant plexiform Schwannoma in the brachial plexus.The patient was a 64-year-old male. More than 30 years earlier, he had experienced numbness in his left upper extremity. By his own account, he had undergone surgery and was diagnosed with a brachial plexus tumor. He stopped visiting the hospital after the surgery, no records of the surgery remain and the details thereof are unknown. The patient was diagnosed with diabetes mellitus 2 years earlier. He had no family history of a similar tumor. The patient noticed muscle weakness in his left arm 5 years earlier, but never visited a medical facility. Thereafter, the muscle weakness worsened, and he finally visited a local doctor 2 years earlier. His upper extremity was far from functional, and so he was referred to our hospital for further examination and treatment.On examination a biloculate mass was observed in the left supraclavicular area, and Tinel's sign caused paraesthesia in his left arm. There was no evidence of the other tumor anywhere on his body. We found no café-au-lait spots or other signs of Recklinghausen disease neither.Manual m