[Schwannomatosis diagnosed from an approximately 30-year history of multiple mononeuropathy accompanied by multiple cauda equina nodules: a case report].

A 51-year-old woman presented with left drop foot at age 20, numbness in the right fourth and fifth fingers at age 45, and numbness in both lower extremities at age 51. Lumbar MRI revealed multiple cauda equina nodules, while ultrasonography of the peripheral nerve identified enlarged nerve bundles in several locations, including the right ulnar and left peroneal nerves. Nerve conduction studies and upper extremity MRI findings were consistent with these observations, and head MRI confirmed the absence of auditory schwannomas. Schwannomatosis (SWN) is a rare disease characterized by the formation of multiple peripheral schwannomas, associated with genetic abnormalities such as SMARCB1 and LZTR1. When multiple peripheral nerve tumors are detected, SWN should be considered as part of the differential diagnosis.