Skin-covered midline spinal anomalies: a report of four rare cases with a discussion on their genesis and milestones in surgical management

The differential diagnosis for a dorsal midline mass presenting in a newborn encompasses a wide range of pathological conditions, including spinal dysraphisms, tumoral overgrowths including teratoma and hamartoma, disturbances in regression of fetal tail, and pseudotail formation.

To present (a) three rare cases of human tails and one case of tethered cord due to a midline anomaly resembling part of a human limb, (b) to discuss different kinds of clinical and pathological conditions which may be encountered in such newborns, (c) to hypothesize a theory about genesis of these congenital lesions, and (d) to remind drawbacks in preoperative evaluations and surgical management of these newborns.

Four newborns with dorsal midline malformations initially diagnosed as heterotopias are presented. Appropriate preoperative investigations and proper surgical interventions leading to resection of the lesions were performed. All four were skin-covered lesions containing well-differentiated cellular elements of fat, vascular, muscular, bony, and cartilaginous origin. Midline spinal dysraphism was detectable both pre- and intraoperatively only in one case in which cord untethering was also performed along with the first surgical intervention. In the other three "tailed cases," midline bone defect could not be detected in the available X-ray films; consequently, simple excision of the tail-like lesions was done. The first patient had to be explored for repeat untethering of the cord after 4 years, but the others have not yet developed any sign of tethering during an average period of 12 years follow-up.

Morphological diagnosis of these lesions is not easy, and the attending pediatrician and neurosurgeon should be familiar with the differential diagnosis of such lesions and be prepared for possible time-consuming operation mandatory to achieve total resection of the lesion in a newborn under general anesthesia. Reviewing the possible theories regarding the genesis of such anomalies, it is hypothesized and suggested that all similar cases could have been of hamartomatous origin rather than defects of embryogenesis.