Differential Diagnosis, Investigations and Treatment
In this case, diagnosis is difficult. Squamous cell carcinoma of the jaw was considered at first impression because the swelling, pain and numbness in the left mandible for more than 4 years. However, according to the imaging results, the lesion developed along the mandibular canal with clear boundaries, so we believed that the lesion was a neurogenic tumor with high probability of benign. In maxillofacial region, the most common neurogenic tumors are schwannoma and neurofibroma. But the clinical and imaging findings of this case did not support these two diagnoses. To determine the nature of the lesion, we performed a fine-needle aspiration biopsy, but the puncture was not successful, so we decided to proceed directly to exploratory excision.
The tumor was totally excised under general anesthesia. During the operation, the tumor was noted along the long axis of the inferior alveolar nerve; appeared white; and had an intact capsule, cystic cavity, and milky cloudy fluid; the inferior alveolar nerve had denatured and could not be distinguished from the mass (Figure 5). The tumor and the adjacent nerve were completely excised during the operation.
Intraoperative frozen sections were obtained for pathological examination. The pathological examination indicated a cystic wall composed of fibrous connective tissue aggregated with a large number of histiocytic and cytoplasm-rich cells (Figure 6). Postoperative immunohistochemical pathology results showed cytokeratin (CK) (-), CD68 (focal +), CD163 (focal +), Ki-67 (+ <2%), S-100 (+), CD56 (+), synaptophysin (Syn) (-/+), SRY-related HMG-box (SOX)-10 (+), neuron-specific enolase (NSE) (-/+), glial fibrillary acidic protein (GFAP) (-), neurofilament (NF) (partial +), and ETS-related gene (ERG) (-) (Figure 7). Immunohistochemical analysis showed the GCT with slightly irregular nuclei surrounded by a few nerve fibers.