Lumbar Epidural Cystic Lesion Associated With Finegoldia magna Discitis Presenting as Cauda Equina Syndrome: A Case Report.

STUDY DESIGN: A case report of a lumbar epidural cystic lesion associated with discitis presenting with cauda equina syndrome. OBJECTIVE: To describe a rare presentation of a lumbar epidural cystic lesion associated with Finegoldia magna discitis presenting with cauda equina syndrome, discuss diagnostic considerations, and highlight the overlap between cystic lesions and infectious epidural pathology. SUMMARY OF BACKGROUND DATA: Discal cysts are uncommon epidural lesions that typically communicate with the intervertebral disc and present with radiculopathy. Severe neurological deficits are unusual, but infectious causes should remain in the differential when findings are atypical. When cauda equina syndrome is suspected, emergent diagnosis and treatment are imperative. METHODS: A 41-year-old male presented with persistent low back pain, bilateral lower extremity radiculopathy, saddle anesthesia, and bowel and bladder changes consistent with cauda equina syndrome. He reported no history of trauma or infectious symptoms. Magnetic resonance imaging revealed a 1.6 × 1.1 cm cystic mass at the L4-L5 disc level that extended into the spinal canal, along with an L5-S1 central disc herniation. He underwent emergent decompression and debridement of the L4-L5 disc space. RESULTS: Histologic examination showed benign fibrocartilaginous tissue compatible with intervertebral disc material, and cultures grew Finegoldia magna (formerly known as Peptostreptococcus magnus). His neurologic symptoms and pain improved immediately after surgery, and he was discharged home on postoperative day four. He was followed clinically and with repeat magnetic resonance imaging, which demonstrated resolution of the cyst and discitis. CONCLUSIONS: Lumbar disc-associated epidural cystic lesions are rare but should be considered in the differential diagnoses in patients with lumbar radiculopathy and/or cauda equina syndrome, and urgent decompression should be performed. This case highlights diagnostic overlap between discal cyst and infectious epidural pathology. LEVEL OF EVIDENCE: Level IV.