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Spinal congenital dermal sinus with dual ostia.

OBJECT
Congenital dermal sinus (CDS) usually develops in the midline of the body as a single tract. To date, only a few patients with multiple CDS tracts and ostia have been reported. The authors analyzed the clinical features of patients with spinal CDS and multiple ostia and proposed a novel hypothesis for the pathogenesis of the atypical CDS.


METHODS
Five patients with spinal CDS and multiple ostia were included. The clinical, radiological, and operative features of these patients were reviewed retrospectively.


RESULTS
Three patients demonstrated bilateral paramedian ostia at the same or a very similar spinal level. One patient showed a paramedian and a midline ostium. One patient had 2 unilateral paramedian ostia at different spinal levels. The layers of the internal ending of CDS tracts were diverse. Complete removal of the tracts was possible in all patients. Two patients had dermoid tumors. All patients had an associated anomaly, such as a lumbosacral lipoma or the Currarino triad. The authors propose a "zipping error" hypothesis for the formation of dual ostia located at the spinal level of primary neurulation. An associated anomaly such as a lumbosacral lipoma may contribute to the formation of dual ostia.


CONCLUSIONS
Unilateral or bilateral dual ostia may be present in patients with CDS, especially when an associated anomaly is present. The atypical CDS may develop from aberrant neural tube closure.