Cranial dermal sinus
Stalk begins with a dimple in the occipital or nasal region. Cutaneous stigmata of hemangioma, subcutaneous dermoid cyst, or abnormal hair formation may occur. Occipital sinuses extend caudally, and if they enter the skull, they do so caudally to the torcular herophili. The presentation may include recurrent bacterial (usually S. aureus) or aseptic meningitis. Evaluation should include MRI to look for the intracranial extension and associated anomalies, including an intracranial dermoid cyst.
Treatment
When operating on a cranial dermal sinus, use a sagittally based incision to permit deep exploration. The tract must be followed completely. Be prepared to enter the posterior fossa.