Cystic schwannoma of the distal forearm. Case presentation

Schwannomas are well-encapsulated, benign tumors arising from Schwann cell constituting the nerve sheaths. We report a case of a cystic conventional schwannoma, measuring 2.5×3 cm, located in the distal forearm of a 33-year-old female patient with no sign of neurofibromatosis type 2 or type 3. The mass was painless, but Tinel's sign was positive. Ultrasonography showed a soft tissue cystic mass diagnosed as being synovial cyst in the left distal forearm. Surgical resection was performed without any complications. Histopathological examinations oriented the diagnosis to a schwannoma, but immunohistochemical stainings proved the tumor origin in Schwann cells and made the differential diagnosis with other pathologies, like neurofibroma, leiomyoma, epithelial cyst, synovial cyst, or ganglion cyst.