Study Design. A patient with sciatica resulting from a hemorrhagic cys
t of the ligamentum flavum is reported. Surgical removal of the cyst r
elieved the patient of her sciatic symptoms. Summary of Background Dat
a. Cyst of ligamentum flavum is an uncommon cause of radiculopathy. Th
ere are 13 cases in the literature. Conclusions. The differential diag
nosis of benign interspinal extradural mass lesions includes spinal sy
novial cysts, ligamentum flavum cysts, perineural cysts, dermoid cysts
, and parasitic cysts.