Classification of Spinal Lipomas Based on Embryonic stage: Overview and Case Series

BACKGROUND: Unsuccessful primary neurulation is usually considered to be the main origin of spinal lipomatous malformations. Yet, we are not able to clarify many of its characteristics using this hypothesis. A new system of spinal lipomatous malformations categorization based on embryological development observed in the course of the first and second stages of neurulation process may be more realistic. OBJECT: The aim of this study was to introduce our experience in the surgical treatment of spinal lipoma correlated with the most recent classification by Morota. METHODS: This study is a retrospective clinical study of 39 cases of spinal lipoma who have been subjected to surgery from August 2007 to May 2019 in neurosurgery department in our institution. The authors classified them to four categories depending on neural tube evolution in the course of embryological growth. Category one is characterized by failing in the first stage of neurulation process; category two includes failing between the first and second stages of neurulation process; category three is characterized as failing in the beginning of the second stage of neurulation process; and category four is characterized as failing in the end of the second stage of neurulation process. We will evaluate the application of this new categorization system. RESULTS: Twenty-one cases of category one, ten cases of category two, six cases of category three and two cases of category four were included in the study. Filar spinal lipomatous malformations were included in category four. Concomitant anomalous disorders were detected only for categorizes 2–4 lipomatous malformations involving failing in the second stage of neurulation process. Only cases with category one lipomatous malformations underwent complete excision. CONCLUSION: Conus medullaris and filum terminale are usually affected in spinal lipomatous malformations and they are the products of the second stage of neurulation process. Evolution of spinal lipomatous malformations looks as an ongoing mechanism involving the first and the second stages of neurulation in some cases. Total excision was feasible for category one only.