Spinal dermal sinuses

Dermal sinuses are congenital malformations, representing a subtype of occult spinal dysraphism (OSD). A short historical review presented by [1] cited the first description of dermal sinuses by Ogle in 1865. The first description in English literature was by Verebely in 1913. The incidence of dermal sinuses is frequently noted as 1:2,500 live births [2, 3]. However, this number is based on two studies from 1954 and 1975, both of which were done before the MRI era, and before it was recognized that coccygeal pits and dermal sinus are two distinct entities. Thus, the true incidence is not known [1]. Dermal sinuses are thought to develop in response to an abnormal separation of the cutaneous and the neural ectoderm between the third and fifth weeks of gestation [4-6]. When this separation fails, a persistent connection, or tract, occurs between the skin and deeper structures. Depending on the degree of incomplete separation, the deeper end of the tract may reach subcutaneous tissue, fascia, dura, or even intradural neural tissue. Another possible underlying mechanism is a defect in notochordal formation with sagittal splitting of the spinal cord and persistence of a cutaneo-endo-mesenchymal fistula.