We herein described a rare case of schwannoma of the hypoglossal nerve in the submandibular region with diagnostic imaging and histopathological findings.
A 31-years-old woman has had a palpable firm, rubbery, freely mobile mass in the submandibular region. Of imaging, MR images showed homogeneous isointensity on T1-weighted imaging (T1-WI), heterogeneous hypointensity on T2-WI, heterogeneous hyperintensity on short T1 inversion recovery (STIR), and heterogeneous enhancement on contrast-enhanced T1-WI. A clear capsule was observed on the margin and showed hypointense on T2-WI. Dynamic MRI showed heterogeneous gradual increased enhancement. The uptake of contrast medium was regionally slow. Diagnostic imaging using CT and MRI was suspected of salivary gland tumor or neurogenic tumor. In consideration of imaging diagnosis, a pleomorphic adenoma or a schwannoma was suspected. Final diagnosis was confirmed on the basis of histopathological finding and intraoperative findings.
1. Histopathologic examination is inevitable, because MR findings are not specific.
2. Schwannomas were said to have specific MRI properties, including specific signs (split-fat sign, fascicular sign, target sign). However, they are not always observed.
3. This case confirmed the differential diagnosis on the basis of the intraoperative finding that the tumor was continuous with the hypoglossal nerve.
Keywords: Schwannoma, Submandibular region, MRI, Antoni type A, Antoni type B, Heterogeneous hypointensity.