Spinal Dermoid and Epidermoid Cyst: An Institutional Experience and Clinical Insight into the Neural Tube Closure Models

Abstract

Objectives The spinal dermoid and epidermoid cysts (SDECs) are rare entities comprising less than 1% of pediatric intraspinal tumors. The present study aims to extrapolate the clinicoradiological data, in order to identify the most plausible neural tube closure model in human and provide a retrospective representation from our clinical experience. Materials and Methods We collected the details of all histologically proven, newly diagnosed primary SDECs who underwent excision over the past 20 years. Secondary or recurrent lesions and other spinal cord tumors were excluded. Surgical and follow-up details of these patients as well as those with associated spinal dysraphism were reviewed. Clinical and radiological follow-up revealed the recurrence in these inborn spinal cord disorders. Results A total of 73 patients were included retrospectively, having a mean age of 22.4 ± 13.3 years, and 41 (56.2%) cases fell in the first two decades of life. Twenty-four (32.9%) dermoid and 49 (67.1%) epidermoid cysts comprised the study population and 20 of them had associated spinal dysraphism. The distribution of SDECs was the most common in lumbosacral region ( n = 30) which was 10 times more common than in the sacral region ( n = 3). Bladder dysfunction 50 (68.5%) and pain 48 (65.7%) were the most common presenting complaints. During follow-up visits, 40/48 (83.3%) cases showed sensory improvement while 11/16 (68.7%) regained normal bowel function. There was no surgical mortality with recurrence seen in eight till the last follow-up. Conclusions The protracted clinical course of the spinal inclusion cysts mandates a long-term follow-up. The results of our study support the multisite closure model and attempt to provide a retrospective reflection of neural tube closure model in humans by using SDECs as the surrogate marker of neural tube closure defect.

Keywords: bladder dysfunction; dermoid; epidermoid; spinal cord tumor; spinal dysraphism.

Fig. 1

Diagram representing order of events involved in primary neurulation. ( A ) The craniocaudal neurulation events involved in mouse embryo. X, Y, and Z marks the initiation of closure sites. ( B ) The Van Allen et al model reflecting the multisite closure in mouse embryos. The beginning of closure sites are recognized as A, B, C, D and E.

Fig. 2

Diagram showing multisite closure model in human embryo. The red triangles are reflecting three initiation sites of neural tube closure (1 indicates the cervical level, 2 represents the mesencephalo–rhombencephalic boundary, and 3 indicates the cranial end of neural groove) and yellow color arrows indicate the directions of neural tube closure. The green arrows indicate the sites of cranial and caudal neuropore.

Fig. 3

Diagram showing secondary neurulation in human embryo. Double blue arrows point toward the filum terminale, and upward-going purple arrow points toward the conus medullaris. The downward-pointed purple arrow indicates the terminal dilatation of the central canal known as ventriculus terminalis.

Fig. 4

( A–C ) Preoperative MRI scan, showing low-lying conus ending at L2–L3 disc space with heterogenous hypointensity on T1WI and hyperintensity on T2WI. ( D ) and ( E ) Postoperative scan showing no residual lesion. ( F ) Hematoxylin and eosin-stained section shows tissue lined by stratified squamous epithelium, with subepithelium showing clusters of sebaceous glands (100X), suggestive of dermoid.

Fig. 5

( A–C ) Preoperative MRI scan lobulated lesion, hypointense on T1WI, while heterogeneously hyperintense on T2WI from L3 to S2, displacing conus and nerve roots. ( D ) and ( E ) Postoperative scan showing no obvious residual lesion. ( F ) Hematoxylin and eosin-stained section shows fibrous wall containing abundant keratin flakes (200X), suggestive of epidermoid.