Bacterial Meningitis Caused by Posterior Fossa Pilonidal Sinus in a Pediatric Patient: A Case Report

Abstract Posterior fossa pilonidal sinus is a rare congenital defect characterized by a dermal sinus tract extending intracranially, potentially connecting with the dura mater or brain tissue. This abnormal passage facilitates bacterial entry into the central nervous system, increasing the risk of severe infections like pyogenic meningitis. We report a pediatric case of bacterial meningitis secondary to an occult posterior fossa pilonidal sinus. Despite receiving full-course, guideline-directed broad-spectrum antibiotic therapy, the patient exhibited persistent signs of infection. The diagnosis was achieved through multidisciplinary consultation combined with characteristic findings on magnetic resonance imaging (MRI). Surgical excision of the sinus tract resulted in complete resolution of the infection, with normalization of laboratory markers and neuroimaging findings. This case underscores the importance of considering occult anatomical defects when intracranial infections fail to respond to standard antimicrobial therapy. Early surgical intervention is crucial for definitive cure and prevention of recurrence.