A Case of Emerging Epidermoid Cyst After Excision of Benign Cystic Teratoma Located in the Conus Medullaris

Teratomas constitute 0.1% of all spinal cord tumors and contain tissues originating from the three germ layers. The aim of surgery in spinal teratomas is total excision. However, total excision of tumors in the conus medullaris may lead to potentially significant morbidities. We aimed to present an epidermoid cyst (EC) after subtotal resection of teratomas. A 19-year-old woman complained of low back pain and numbness in the posterior aspect of the left leg. Magnetic resonance imaging (MRI) showed a tethered cord and an intradural lesion at the L4 level. During surgery, part of the capsule was left. Histopathological examination was reported as a benign cystic teratoma. Thirty-three months later, a control follow-up MRI showed a cystic lesion at the L4 level. After the total excision of the lesion, a neuro deficit developed. Histopathological examination was reported as EC. Spinal ECs account for less than 1% of spinal tumors. These tumors are lined with stratified squamous epithelium, similar to the skin's epidermis, and arise from the pathological displacement of epidermal cells into the spinal canal. It should be remembered that EC may develop after incomplete resection of conus medullaris-localized teratomas, and complete resection of these masses may result in neurological deficits.