Idiopathic spinal intramedullary epidermoid cyst arising in the thoracic region: illustrative case

BACKGROUND: Spinal epidermoid cysts are rare tumors typically found in the lumbosacral region in the intradural extramedullary space. These tumors are usually caused by defects in neural tube closure or acquired through iatrogenic or traumatic insult, with either mechanism leading to the inclusion of epidermal cells in cystic compartments in the spine. Although benign, these cysts can cause symptoms including back pain and weakness, and patients often undergo resection. OBSERVATIONS: We present a unique case of an intramedullary spinal epidermoid cyst appearing in the T6-7 region of a 69-year-old male. Furthermore, subcutaneous epidermoid cysts within the same region as the spinal tumor were observed. A review of the literature revealed that while intramedullary spinal epidermoid cysts are rare, their concurrent appearance with subcutaneous cysts has not been observed, demonstrating the novelty of this case. LESSONS: This case demonstrates the possible occurrence of epidermoid cysts in the intramedullary space, in superior spinal regions, and in the older population. Additionally, such cysts should remain on the differential in individuals with myelopathic symptoms and associated subcutaneous inclusion cysts on the back. Careful imaging to guide diagnoses and surgical planning is crucial. https://thejns.org/doi/10.3171/CASE26313.