Split cord malformation associated with congenital dermoid cyst and myeloschisis - case-based literature review on possible embryonic derivation and implications

Split cord malformation co-existing with either congenital dermoid or myeloschisis has been previously reported. Theories exist which explain the underlying embryopathy behind the occurrence of each of these anomalies in conjunction with split cord malformation. However, the occurrence of all three anomalies in the same patient, to the best of our knowledge, has not yet been reported in the literature. We report two cases on the co-existence of congenital dermoid cyst with both myeloschisis and split cord malformation and review the literature on previous postulations of mechanisms that could possibly explain the simultaneous occurrence of all three distinct anomalies. They involve all three primary germ layers and therefore share a common embryonic origin from the epiblast. We try to explain their co-existence based on the theory of notochordal splitting and endomesechymal tract formation consequent on endodermal-ectodermal adhesion as postulated by Beardmore and Wigglesworth and discuss on implications in terms of treatment paradigms. The unusual combination of all three anomalies in both patients probably highlights a need for further research on their pathogenesis despite these previous theories. These cases demonstrate the fact that currently accepted embryological explanations of most pathologies especially outliers still fall short with much remaining to be understood.