Radiological and pathological findings of spinal intramedullary granular cell tumor.

Background: Granular cell tumors (GCTs) are rare, usually benign, tumors with classic histomorphology. This tumor can occur throughout the body, but the spine is a distinctly rare location. Here, we report a very rare case of intramedullary GCT arising in the thoracic spinal cord. Case Description: A 36-year-old woman presented to our hospital with an approximately 1-year history of gradually worsening numbness in the left toe and weakness in both lower limbs. Neuroimaging showed a tumor mass in the upper spine at the level of thoracic vertebrae 7-8, appearing hypointense on T2-weighted imaging (WI) and showing uniform gadolinium enhancement on T1-WI. Complete surgical resection was successfully performed. Histopathological examination revealed round or polygonal cells with abundant granular eosinophilic cytoplasm strongly staining for S-100 and SOX10, and benign intramedullary GCT in the thoracic spinal cord was diagnosed. Postoperative magnetic resonance imaging (MRI) showed no residual tumor, and the patient recovered well from this intervention, showing no sequelae. Follow-up neuroimaging after 2 years showed no signs of recurrence. Conclusion: This report describes an extremely rare case of GCT arising from the intramedullary thoracic spinal cord, which is difficult to diagnose by routine neuroimaging. Therefore, accurate diagnosis requires careful identification of clinical signs, MRI including hypointensity on T2-WI, and analysis of combined morphologic and immunohistochemical studies.