Schwannomatosis is a rare genetic disorder characterized by the development of multiple non-cancerous (benign) nerve sheath tumors called schwannomas. These tumors grow along the peripheral nerves. Schwannomatosis is part of a group of related disorders known as neurofibromatoses, which includes Neurofibromatosis type 1 (NF1) and Neurofibromatosis type 2 (NF2).