A dermal sinus is a small congenital opening in the skin with a narrow tract lined by epithelium, which typically occurs at the spinal or cranial end of the neural tube1. The most common location is in the lumbosacral region of the spine.
Spinal Dermal Sinus
A dermal sinus can occur in the spinal region and is then usually located near the midline, with an opening measuring 1-2 mm2. The sinus may end very superficially or may extend as far as the dural sac. The sinus may expand at any point; when this expansion is lined by squamous epithelium, it is referred to as an epidermoid cyst. If the cyst is lined by dermis, it is referred to as a dermoid cyst3.
Cranial Dermal Sinus
A dermal sinus can also occur cranially, in which case it is usually located in the nasal or occipital region4. If the dermal sinus is located in the occipital region, it extends into the skull caudal to the Torcula. A cranial dermal sinus may typically present with recurrent bacterial or aseptic meningitis5. MRI should be performed for further evaluation to assess both the intracranial extent and the presence of an intracranial dermoid cyst.
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