Peculiar bony involvement of sinus pericranii in children: Extensive diploic erosion in three "karstic" variants

Object: Sinus pericranii (SP) is a rare, benign, extradural venous anomaly whose extracranial connection consists in an enlarged subgaleal drainage composed of a network of thin-walled veins that form a varix on the external table of the skull. In the present series of three patients we present three variantesof SP which have never been described, characterized by an extensive diploic erosion causing a "karstic" effect.

Methods: A systematic review was conducted in compliance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline. A comprehensive search for relevant articles was performed on PubMed from 1992 to 2022 using the following search words: "sinus pericranii".

Results: The search produced 77 articles with 137 patients. In all the cases analysed, there were not reported any patients with extensive diploic erosion, namely "karstic" variants. So, the authors present clinical history, neuroimages, treatment strategies and outcome of 3 patients with a "karstic" SP with the aim to describe this clinicradiological entity.

Conclusions: In this study, our group identified a peculiar variant of SP characterized by bony involvement with extensive diploic "karstic" erosion of diploe, with possible tendency to enlarge during time.