Ligamentum Flavum Cyst: Rare Presentation Report and Literature Review

Ligamentum flavum cysts (LFC) are uncommon and their differentiation from other Juxta-facetal cysts & epidural cystic lesions is difficult based on imaging techniques. We present one such rare case of ligamentum flavum cyst with relevant review of the literature. An eighty-eight years male presented with progressively worsening radicular symptom in the left lower limb. His neurological examination was unremarkable. Magnetic resonance imaging of lumbar spine revealed an epidural cystic lesion narrowing the left lateral recess. Intra-operatively, a mass was found originating from ventral surface of ligamentum flavum. Pathological examination was suggestive of fibro-collagenous tissue without synovial lining. The exact pathogenic mechanism for the formation of LFCs is not well understood. Association with segmental instability and degenerative conditions of spine is postulated. They are commonly seen at the mobile junctional levels of the spine. Persistent micro-traumatic events with abnormal movement maybe contributory to their origin. They present either with radiculopathy or neurogenic claudication symptoms owing to compressive effect on adjacent neural structure. LFC should be considered as a differential in patients with radicular pain or claudication symptoms with epidural cystic lesion seen on MRI. Complete excision of such lesion provides excellent pain relief in symptomatic individuals.