Intraneural ganglion cyst of the lumbosacral plexus mimicking L5 radiculopathy: A case report

BACKGROUND: Intraneural ganglion cysts are benign gelatinous masses that form within the epineurium of a peripheral nerve. Only few cases of intraneural ganglion cyst arising from the hip joint have been reported. CASE SUMMARY: A previously healthy 65-year-old woman who had been experiencing left buttock pain radiating to the dorsum of the foot for 2 years visited our clinic. Prior to visiting the clinic, she underwent lumbar spine magnetic resonance imaging and received physiotherapy, pain killers, and epidural injections based on a presumptive diagnosis of spinal stenosis for 2 years in other hospitals. Repeat magnetic resonance imaging revealed joint connection of the articular branch of the hip joint and rostral extension of the cyst along the L5 spinal nerve near the L5-S1 neural foramen. The patient was diagnosed with intraneural ganglion cyst arising from the articular branch of the hip joint based on high-resolution magnetic resonance neurography. Using the arthroscopic approach, a cystic opening within the intra-articular space was detected, and cyst decompression was then performed. The pain in the left leg was significantly relieved during the 6-mo follow-up. CONCLUSION: Although intraneural ganglion cysts arising from the hip joint are rare, they can cause typical radicular pain and mimic common L5 radiculopathy. Typical cyst ascent phenomenon starting from the termination of the articular branch on magnetic resonance imaging is a crucial finding indicative of intraneural ganglion cysts arising from the hip joint.