Diagnosing a rare thoracic intramedullary spinal dermoid cyst using DWI with ADC mapping: Case report

INTRODUCTION: Dermoid cysts are rare lesions generally associated with embryological errors that occur during neural tube closure. Intramedullary lesions are extremely rare, especially within the upper thoracic spinal cord. CASE PRESENTATION: We report a case of a 19-year-old male who had an intramedullary thoracic dermoid cyst presenting with progressive ataxia, lower limb weakness, and hyperreflexia. MRI demonstrated a 1.2 × 1.8-cm intramedullary thoracic dermoid cyst causing significant spinal cord compression, which was successfully removed via full resection. The patient had an uncomplicated postoperative course, with improvement in preoperative deficits. DISCUSSION: This is a unique case documenting a thoracic spinal cord intramedullary dermoid cyst not associated with trauma or congenital abnormality of the spinal cord. CONCLUSION: We highlight the importance of future inclusion of diffusion-weighted magnetic resonance (MR) imaging (DWI) with apparent diffusion coefficient (ADC), an imaging modality that detects differences in cellularity of spinal cord lesions, for earlier diagnosis of dermoid cyst.