Ligamentum flavum hematoma in the lumbar spine.

A previously healthy 45-year-old woman presented with ligamentum flavum hematoma manifesting as radicular leg pain. Neurological examination findings were consistent with L-5 root compression. An old hematoma inside the degenerated ligamentum flavum was drained. The cyst showed no connection to the facet joint. Complete resection of the mass was performed, resulting in excellent pain relief. The most common cystic lesion in the lumbar spine is synovial cyst associated with the facet joints, but ligamentum flavum hematoma should be included in the differential diagnosis. The preoperative diagnosis can be based on computed tomography and magnetic resonance imaging findings of degenerative thickening of the ligamentum flavum associated with a fluid component.