Infratentorial abscess secondary to dermal sinus associated with dermoid cyst in children: Review of the literature and report of a rare case

BACKGROUND: Dermal sinus is usually located at either end of neural tube but most commonly lumbosacral. When occipital, it extends caudally and is mostly localized in the midline position or in the cavity of the fourth ventricle. It could communicate with the skin through a fistula with potential risk of deeper abscesses. Posterior fossa abscess secondary to dermal sinus associated with intracranial dermal cyst is an uncommon pathology. CASE DESCRIPTION: A 24-month-old girl was admitted to our institution with a cutaneous fistula in the midline of the occipital region. Brain imaging showed an infratentorial intradiploic cyst with peripheral enhancement to contrast medium. The mass showed hyperintensity on T1-weighted sequences, with the lower signal on T2-weighted images. A suboccipital craniotomy was performed with evacuation of the abscess and excision of the capsule. Contextually a 3 cm whitish and encapsulated cystic mass with hair component was extracted. Histology confirmed the diagnosis of abscess associated with dermal cyst and dermal sinus. The patient condition improved and 15 days after excision, was discharged. The postoperative MRI showed total removal of the lesion. A 36-month follow-up highlighted no evidence of recurrence. CONCLUSION: Posterior fossa dermoid cyst should be considered in all children with a cutaneous fistula. Early neurosurgical treatment of these benign tumors should be performed to prevent the development of severe intracranial infection. Best results are associated with early diagnosis and complete removal of the abscess. The present work further reviews the few similar cases that have been reported in the literature confirming the need for future research.