HYPOGLOSSAL NEURILEMMOMA IN THE SUBMANDIBULAR REGION A DIAGNOSTIC DILEMMA

Pleomorphic adenoma is a common benign salivary gland tumor, predominantly found in the parotid gland, with only 10% occurring in the submandibular gland. It is a mixed tumor comprising epithelial, myoepithelial, and mesenchymal components. Hypoglossal schwannomas, on the other hand, are extremely rare, with an undefined incidence. These tumors arise from Schwann cells, responsible for myelin sheath formation, and can occur anywhere along the course of the hypoglossal nerve. Due to their proximity to the submandibular gland, they are frequently misdiagnosed as submandibular pleomorphic adenomas. We report a 24-year-old female presented with a gradually enlarging right submandibular swelling over two years, with occasional swallowing discomfort. Clinical evaluation revealed a firm, spherical 6×6 cm mass without speech abnormalities. Ultrasonography and CECT neck suggested pleomorphic adenoma, confirmed by FNAC. The patient underwent elective submandibular gland excision. Intraoperatively, a separate lesion arising from the hypoglossal nerve was discovered and carefully dissected. Postoperatively, she had mild tongue deviation and facial asymmetry, which resolved in three weeks. Histopathology confirmed a benign schwannoma. Preoperative diagnosis is challenging, with studies showing only 6% accuracy. Similar cases have been misdiagnosed as submandibular adenomas, emphasizing the diagnostic dilemma. MRI features, such as split-fat, fascicular, and target signs, aid diagnosis, but findings are not always conclusive. Histopathological examination remains the gold standard. Thus Hypoglossal neurilemmoma is a rare entity often mistaken for submandibular pleomorphic adenoma. Awareness of this differential diagnosis is crucial to prevent misdiagnosis and ensure appropriate surgical management.