A rare case of intradural and extramedullary epidermoid cyst after repetitive epidural anesthesia: case report and review of the literature

BACKGROUND Spinal epidermoid cysts are benign tumors, which are rarely seen as an intradural extramedullary spinal cord tumor in the conus medullaris region. Acquired spinal epidermoid cysts are mostly caused by iatrogenic procedures, such as lumbar puncture, and the majority of acquired spinal epidermoid cysts have been reported below the L1 level, because lumbar puncture is usually performed around the iliac crest. Here, we report an extremely rare case of an epidermoid cyst that occurred as an intradural and extramedullary spinal cord tumor attached to the conus medullaris after repetitive epidural anesthesia. CASE PRESENTATION A 67-year-old female presented with a low back pain and left sciatica. Although the patient had experienced occasional mild low back pain for several years, her low back pain markedly worsened 2 months before her visit, as well as newly developed left sciatica resulting in intermittent claudication. She had a history of several abdominal surgeries. All abdominal procedures were performed under general anesthesia with epidural anesthesia in her thoracolumbar spine. Magnetic resonance imaging of her lumbar spine demonstrated an intradural extramedullary spinal cord tumor at the T12-L1 level. Because her symptoms deteriorated, the tumor excision was performed using microscopy. Histological examination of the specimens demonstrated that the cyst walls lined with stratified squamous keratinizing epithelium surrounded by the outer layer of collagenous tissue with the absence of skin adnexa. A diagnosis of epidermoid cysts was confirmed. Her MRI showed complete resection of the tumor, and there was no recurrence at 2-year follow-up. CONCLUSIONS In this case report, epidermoid cells might be contaminated into the spinal canal during repetitive epidural anesthesia. The patient was successfully treated by complete resection, and there was no recurrence at 2-year follow-up with a good clinical outcome. However, long-term follow-up is required for a potential risk of tumor recurrence.