Abstract
Background: Spinal intradural arachnoid cyst is a rare lesion, sometimes acquired.
Purpose: To describe the appearance and later spontaneous disappearence of a lumbar intradural arachnoid cyst, following perineural corticoid injections.
Method: Review of the clinical data and imaging, with final spontaneous return to initial state.
Discussion: Atypical intradural arachnoid cysts can be related to perineural injections and can cause symptoms of spinal stenosis. Its spontaneous vanishing is a very rare event, up to now unreported.