Cerebellar abscess secondary to dermal sinus associated with dermal cyst in children: review of the literature and report of a rare case

Introduction: Dermal sinus occur in the cranial vault, and the occipital region. Rarely, is localized in the posterior fossa, particularly 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 (0,1 to 0,7 %). Methods: A 24-month old girl was admitted to our institution with a cutaneus fistula in the midline of the occipital region. A CT scan and brain MR showed a sottotentorial intradiploic cyst with peripheral enhancement and edema. The mass was hyperintensity on T1-weighted sequences, with lower signal on T2-weighted images. A suboccipital craniotomy was performed with evacuation of the abscess and an excision of the visible capsule with a total removal of a 3 cm whitish, midline, encapsulated cystic mass with hair component. Results: The histologic examination confirmed the diagnosis of abscess associated with dermal cyst and dermal sinus. Post-operative course was uneventful. The patient experienced a sudden improvement of cephalalgia and 15 days after the microsurgical excision, was discharged. On postoperative RM imaging, it was found the total removal of the lesion. A 36 month follow-up no evidence of recurrence. Discussion: Posterior fossa dermoid cyst should be considered in all children with a cutaneus fistula. Early neurosurgical treatment of these benign tumours should be performed to prevent the development of severe intracranial infection. Best results were obtained in cases of early diagnosis and the complete removal of the abscess. The reported case passes through a review of similar cases riported in the literature confirm the rarety of the case report.