Spontaneous regression of a sacral Tarlov cyst.

Tarlov cysts or perineural cysts are extradural cerebrospinal fluid (CSF)-filled sacs commonly found in the sacral spine. Their clinical significance is often underestimated due to diagnostic challenges. This case report describes a female patient presenting with rectal pain, coccydynia, dyspareunia and urinary symptoms. Initial imaging revealed a 4 cm Tarlov cyst at the S3 level, along with two smaller cysts between the S1 and S2 vertebrae. Despite significant symptomatology, spontaneous regression of the S3 cyst was observed within 4 months, leading to the cancellation of a scheduled surgical intervention. This case is notable as spontaneous regression of Tarlov cysts is exceedingly rare, with only one prior documented instance. This report suggests a potential dynamic process involving CSF flow in and out of the cyst which may contribute to the growth of the lesion but also, in rare cases, to a decrease in size up to complete disappearance.