Interdisciplinary Neurosurgery (Sep 2020)
Clinicopathological findings of limited dorsal myeloschisis associated with spinal lipoma of dorsal-type
Abstract
Purpose: Limited dorsal myeloschisis (LDM) is thought to arise from focal incomplete disjunction between the cutaneous and neural ectoderm during primary neurulation, while spinal lipoma of dorsal-type (dorsal lipoma) arises from premature disjunction. Thus, simultaneous occurrence of an LDM and dorsal lipoma are not surprising, and may represent slightly different perturbations of disjunction caused by the same insult in neighboring loci. However, the clinicopathological findings of the LDM with dorsal lipoma have not been fully determined. Methods: Of 21 patients with LDM, 3 (14.3%) had dorsal lipoma. We retrospectively analyzed the clinicopathological findings of these 3 patients, especially the histopathological distribution of the fibrocollagenous LDM tract and fibroadipose tissue of the lipoma. Results: Patients 1 and 2 had flat skin lesions, while patient 3 had a human tail-like cutaneous appendage. In the tethering stalks linking the skin lesion at the lumbosacral lesion to the low-lying conus medullaris of the three patients, fibrocollagenous tissues embedding adipose tissues at the subcutaneous site, and with abundant adipose tissues at the extradural site, were changed to fibroadipose tissue at the intradural site. While glial fibrillary acidic protein-immunopositive neuroglial tissues were observed in 2 (patients 1 and 2), peripheral nerve fibers were observed in every stalk. Smooth muscle fibers were noted in patient 1, while a large amount of striated muscle fibers were seen in patients 2 and 3. Conclusion: These cases showed various tissues with different origins in the stalk. There may also be a seamless continuation between fibrocollagenous LDM tissue at the distal site and lipomatous tissue at the proximal site. Peripheral nerve fibers and smooth muscle fibers of neural crest origin may be dragged into the stalk during incomplete disjunction, while the striated muscle fibers of mesodermal origin may enter the stalk along with the lipomatous tissues during premature disjunction.
