A dermal sinus tract is a form of occult spinal dysraphism. Embryologically, it results from a focal incomplete disjunction of the surface ectoderm and dermal elements from the neuroectoderm. This process likely occurs between the third and eighth weeks of gestation. Later during embryogenesis, the spinal cord ascends relative to the spinal canal and stretches the adhesion cephalad into a long, tubular tract. Dermal sinus tracts are therefore abnormal communications extending from the skin surface to the spinal fascia, dura mater, or neural elements, and are lined with epithelium. Although dermal sinuses can occur anywhere from the upper cervical region to the midsacrum, they are most commonly found in the midline in the lumbar or lumbosacral area. Some dermal sinuses end blindly within the soft tissues superficial to the underlying lamina, but 60–70% reach the subarachnoid space, half attaching to the filum or the conus.
KeywordsDermal sinus Dysraphism Coccygeal pit Intradural Dermoid Epidermoid
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