Introduction: Sinus pericranii is a rare vascular malformation that connects the intracranial dural sinuses to the extracranial venous drainage system and is caused by either trauma or congenital defects. Although the majority of these vascular structures are due to trauma, some are congenital. Case report: Herein, we report a 5-month-old patient with a very large and fluctuating subcutaneous mass over the occiput and the diagnosis of Crouzon’s syndrome. The child presented with a large midline mass that on imaging, connected to the underlying torcular and was diagnosed as a sinus pericranii. At long-term follow-up and without operative intervention, the sinus pericranii resolved. This uncommon relationship is reviewed. Conclusion: Premature closure of posterior fossa sutures as part of Crouzon’s syndrome can present with large sinus pericranii. Such subcutaneous swellings might resolve spontaneously.