Oral plexiform schwannoma: A case report and relevant immunohistochemical investigation

Schwannomas are benign peripheral nerve sheath tumors originating from the Schwann cells. Most schwannomas in the head and neck region are solitary; however, multiple schwannomas affecting one or more nerves suggest a possible association with neurofibromatosis type 2 and schwannomatosis. Plexiform schwannoma is a rare variant of conventional schwannoma that is characterized by intraneural multinodular growth. This grow pattern has also been observed with other neural tumors which may make diagnosis more difficult. Herein, we report the case of a 28-year-old woman who presented a solitary plexiform schwannoma of great palatine nerve. In the present case, we focused on immunohistochemical analysis in daily practice for the differential diagnosis of schwannomas and their mainly morphological mimics, especially with plexiform neurofibroma, granular cell tumor and malignant peripheral nerve sheath tumors. We also discussed on SMARBC1/IN1 marker usefulness in combination with brain magnetic resonance imaging for the distinction of solitary schwannoma from neurofibromatosis type 2 or schwannomatosis.