Schwannoma is a slow-growing, benign tumor of the peripheral nerves arising from the Schwann cells. We report a rare case of a schwannoma originating from the submandibular branch of the lingual nerve. A 26-year-old man presented with a painless right submandibular swelling, and CT revealed a 4.5-cm tumor arising from the right submandibular gland. Despite the tumor being so large, ultrasonography-guided fine-needle aspiration cytology (FNAC) failed to provide a definitive diagnosis. Adhesion of the tumor to the lingual nerve was noted during resection of the tumor along with the submandibular gland. Microscopic examination revealed a well-encapsulated tumor composed of spindle-shaped cells in a palisading arrangement. We concluded that the tumor was a schwannoma arising from the submandibular ganglion. Paralysis of the marginal mandibular branch of the facial nerve developed as a postoperative complication, although the patient recovered from this complication by 3 months after the surgery. There was no evidence of lingual nerve paralysis.
The lack of specific symptoms sometimes makes it difficult to make an accurate preoperative diagnosis of schwannoma. Even MRI fails to distinguish between schwannoma and pleomorphic adenoma, which is the most commonly occurring tumor of the submandibular gland, and FNAC also often fails to yield the diagnosis. We review nine cases of schwannoma arising from the lingual nerve or the submandibular ganglion and discuss their clinical findings.
