Intradural dermoid cyst with complete dermal sinus of the posterior fossa: Contribution of 3D imaging with histopathological correlation.

A 5-year-old girl who presented with two episodes of meningitis, had a patchy red area and a small skin dimple in the midline of the occiput on physical examination. Imaging revealed a well-demarcated oval intradural lesion of the posterior fossa with restricted diffusion and peripheral enhancement, raising the possibility of an abscess. The 3D volume rendering of CT images of the inner surface of bone showed chronic bone remodeling and a tiny bone defect of the outer table. This detailed anatomical evaluation has an added value to MRI characteristics to orient for a preoperative diagnosis of an intradural dermoid cyst with a dermal sinus, that was confirmed by histopathological analysis after surgical excision.