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Histopathological findings of the resected specimens. Each section except for (a) is indicated in Fig. 2(a-3). (a) The image shows no fibrocollagenous tract continuous with the skin tissue, which had finely jagged squamous epithelium; however, subcutaneous mature fibroadipose tissue (fat) is noted. (b–f) Longitudinal section of the intradural tract showing a fibrocollagenous tract embedded with glial fibrillary acidic protein (GFAP)-immunopositive neuroglial tissues (c–e) and peripheral nerve fibers with ganglion cells (f). (g–i) Longitudinal sections of the stalk-dura attachment show dense fibrocollagenous tissue (shown in Mason’s trichrome staining (M-T) in (h)) embedded with peripheral nerve fibers with ganglion cells (i) and an arachnoid tissue (j). (k, l) The wall of the syringomyelia consists of GFAP-positive neuroglial tissues. (m–o) Longitudinal section of the filum showing fibrocollagenous tracts embedded with a large amount of mature adipose tissue (fat), neuroglial tissue (n), and peripheral nerve fibers with ganglion cells (o). Large vessel (Ves) is also noted
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Background:
Limited dorsal myeloschisis (LDM) is characterized by a fibroneural stalk linking the skin lesion to the underlying spinal cord. CASE PRESENTATION : A 7-month-old girl with a lumbosacral "cigarette-burn" flat skin lesion underwent untethering surgery. The intradural tethering stalk appeared to originate at the dural wall and join the c...
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Purpose
Limited dorsal myeloschisis (LDM) is characterized by a fibroneural stalk linking the skin lesion to the underlying spinal cord. On account of the external skin lesion, all LDMs are either flat (nonsaccular) or saccular, and a human tail-like cutaneous appendage has not been reported.
Methods
In our 14 LDM patients, 2 had tail-like appenda...
Citations
... [20] Ectopic or heterotopic ganglion cells, that are not fully formed DRG, are sometimes microscopically revealed by postoperative histopathological investigation in a normal terminal filum and in cases with neurulation disorders such as spinal lipoma, limited dorsal myeloschisis, and retained medullary cord. [5,10,[13][14][15]17,18,21] Conner et al. recently described an ectopic DRG in cauda equina in an adult case without spinal cord malformation, which had been preoperatively recognized as a cauda equina tumor. [1] We treated a pediatric case with an ectopic DRG in cauda equina who had a fatty terminal filum and bifid sacrum. ...
Background
A heterotopic dorsal root ganglion (DRG) is sometimes observed in the vicinity of dysplastic neural structures during surgery for open spinal dysraphism; however, it is rarely associated with closed spinal dysraphism. Distinguish from neoplasms by preoperative imaging study is difficult. Although the embryopathogenesis of a heterotopic DRG has been speculated to be migration disorder of neural crest cells from primary neural tube, its details remain unelucidated.
Case Description
We report a pediatric case with an ectopic DRG in cauda equina associated with a fatty terminal filum and bifid sacrum. The DRG mimicked a schwannoma in the cauda equina on preoperative magnetic resonance imaging. Laminotomy at L3 revealed that the tumor was entangled in the nerve roots, and small parts of the tumor were resected for biopsy. Histopathologically, the tumor consisted of ganglion cells and peripheral nerve fibers. Ki-67 immunopositive cells were observed at the periphery of the ganglion cells. These findings indicate the tumor comprised DRG tissue.
Conclusion
We report detailed neuroradiological, intraoperative and histological findings and discuss the embryopathogenesis of the ectopic DRG. One should be aware of the possibility of ectopic or heterotopic DRGs when cauda equina tumors are observed in pediatric patients with neurulation disorders.
... However, the most notable finding is that there was no extradural stalk continuous to the CDS. We speculated that the originally existing extradural stalk, linked to the CDS with the skin lesion, subsequently regressed and was replaced by adipose tissue, as in the case reported by Hiraoka et al. [16]. ...
Limited dorsal myeloschisis (LDM) is characterized by a fibroneural tethering stalk linking the skin lesion to the underlying spinal cord. LDM without an extradural stalk is rare. A full-term boy was noted at birth to have a dimple in the upper back (dorsal skin of the lower thoracic region). Computed tomographic scan showed spina bifida at the T9–12 vertebral level and osteochondral tissue at the T10 level. Magnetic resonance imaging (MRI) demonstrated a tiny dorsal lipoma at the T8 vertebral level, but the intradural tethering tract was not apparent. At 18 days of age, the congenital dermal sinus (CDS) tract started from the dimple and terminated at the osteochondral tissue, without continuity of the dura mater, and the osteochondral tissues were resected. At age 2 years 8 months, he developed spastic paresis of the right foot. On MRI, the tethering tract from the dorsal lipoma became apparent. During the second surgery at age 2 years 11 months, the intradural stalk started from the dorsal lipoma and joined the inner surface of the dura mater was untethering from the cord. Postoperatively, right spastic paresis was improved. Histological examination of the intradural stalk revealed the distribution of S100-immunopositive peripheral nerve fibers, which is one of the histopathological hallmarks of LDM. We speculated that the extradural stalk with coexisting CDS originally linked from the skin lesion subsequently regressed and was replaced by fibroadipose tissue with osteochondral tissue migration. Intradural exploration should always be seriously considered in these disorders of persisting neurocutaneous connection.
... e detailed clinicopathological findings of LDM in Patients 6-10 have been described before [ Table 2]. [6,9,[12][13][14] In all patients, the filum was resected as a column and placed in formalin. Routinely prepared histopathological sections were stained with hematoxylin and eosin or immunostained for glial fibrillary acidic protein (GFAP) and S-100 protein as part of the standard diagnostic analysis. ...
Background
Closed spinal dysraphism of primary neurulation failure could be associated with filar anomalies, such as filar lipoma or thickened and tight filum terminale (TFT), resulting from impaired secondary neurulation. Retained medullary cord (RMC) is a remnant of the cavitary medullary cord originating from the secondary neurulation failure. Some filar lipomas are known to contain a central canal-like ependyma-lined lumen with surrounding neuroglial tissues (E-LC w/NGT), that is, a characteristic histopathology of RMC. To clarify the embryological background of these filar anomalies, we evaluated the histopathological findings.
Methods
Among 41 patients with lesions of primary neurulation failure who underwent initial untethering surgery, the filum including cord-like structure (C-LS) was additionally resected in 10 patients (five dorsal and transitional lipomas; five limited dorsal myeloschisis). We retrospectively analyzed the clinical, neuroradiological, intraoperative, and histopathological findings.
Results
Among 10 patients, two patients were diagnosed with RMC based on morphological features and intraoperative neurophysiological monitoring. The diagnosis of filar lipoma was made in six patients, since various amounts of fibroadipose tissue were histopathologically noted in the filum. Two patients were diagnosed with TFT, since the filum was composed solely of fibrocollagenous tissue. E-LC w/NGT was noted not only in both C-LSs of RMCs but also in two out of six fila both with filar lipomas and fila with TFTs.
Conclusion
These findings provide further evidence for the idea that entities, such as filar lipoma, TFT, and RMC, can be considered consequences of a continuum of regression failure occurring during late secondary neurulation.
... Variations in the exact cellular types and histological configurations of FSND lesions account for the spectrum of nondisjunctional disorders, and partial atresia of a tract may explain certain variants of the full forms 8) . Concerning the documentation of the "level" of a FSND, it should reflect the spinal cord level of the initial causative nondisjunctional error, and accordingly, it should be the level of the laminar defect through which the fibroneural stalk or sinus tract passes. ...
... In a report of ten intramedullary spinal dermoid cysts, nine had a traceable CSDST 7) . The rare occurrence of spinal dermoid cyst without a sinus tract is probably due to isolated sequestration of pluripotent SE cells or atresia of the outer tract 8) . ...
... In all instances, the fibroneural stalk, extending from the deeper side of the abnormal skin, ultimately merges with the spinal cord. Only one example of a discontinuous stalk has been documented 8) . In all LDMs, the spinal cord is tethered to the surface myofascial tissue by the fibroneural stalk 22,34,35) and by the meningeal and other mesenchymal investments condensed around the stalk. ...
Spinal dysraphic lesions due to focal nondisjunction in primary neurulation are commonly encountered in paediatric neurosurgery, but the "fog-of-war" on these conditions was only gradually dispersed in the past 10 years by the works of the groups led by the senior author and Prof. Kyu-Chang Wang. It is now clear that limited dorsal myeloschisis and congenital spinal dermal sinus tract are conditions at the two ends of a spectrum; and mixed lesions of them with various configurations exist. This review article summarizes the current understanding of these conditions' embryogenetic mechanisms, pathological anatomy and clinical manifestations, and their management strategy and surgical techniques.
... [11][15] [16] The complementary diagnosis of DLM is based on the histopathological evaluation and with the finding of neural elements, as peripheral nerve fibers and the positivity for GFAP-immunopositive neuroglial tissue in the immunohistochemical evaluation of the fibrocollagenous band. [12][17] [13] In the case reported, despite evident anatomical relationship between the intra/extradural fibroneural stalk and the dorsal cutaneous appendage, GFAP was negative in the immunohistochemical evaluation of the stalk. The positivity of GFAP is difficult with conventional histopathological examination, since small islands that would demonstrate reactivity may be lost, during the cut of the stalk and the selection of small fragments to be evaluated. ...
INTRODUCTION
Limited dorsal myeloschisis (LDM) is a recently described pathological entity, characterized by a defect of the closed focal neural tube and a fibroneural pedicle connecting the cutaneous lesion to the spinal cord.
PRESENTATION OF THE CASE
This case describes a 9-month-old child with a human tail and an underlying spinal dysraphism. This was represented by LDM stalk associated with a medullary lipoma, in connection with the dorsal cutaneous appendage. We also report the therapeutic proposal for this case and its clinical outcome.
DISCUSSION
LDM is a distinctive clinicopathological presentation of a spinal dysraphism, associated with numerous anomalies, such as lipomyelomeningocele, tethered cord, lipoma, congenital heart disease and teratoma. In this case, surgical treatment for LDM consists of surgical resection of the appendage, untethering of the spinal cord and resection of conus medullaris lipoma in the same procedure.
CONCLUSION
In this case report, we share the experience of a referral service in pediatric neurosurgery regarding clinical and radiological diagnosis, and the successful treatment of this rare type of congenital malformation. Therefore, clinicians should be aware of possible morphological variations of the skin lesion associated with LDM.
... From April 2015 to March 2020, 21 Japanese patients with LDM underwent initial untethering surgery at Kyushu University Hospital and related hospitals. The clinical diagnosis of LDM was based on a comprehensive histological examination and the patients' clinical manifestations, as described previously [4][5][6]10,13,14]. As an external skin lesion, 13 patients had flat lesions, 3 had saccular lesions, and 5 had human 4 tail-like cutaneous appendages. ...
... These findings support our speculation that there may be a seamless continuation between fibrocollagenous LDM tissue at the distal site and lipomatous tissue at the proximal site. Filar-type lipoma or fatty filum is another lipoma with a high frequency of association with LDM [4,5,13,14], and was observed in patient 3. Because filar lipomas result from failed secondary neurulation [12,19], coexistence with LDM is thought to be coincidental. ...
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.
... In the original description by Pang et al. [12], 2/63 LDM patients had syringomyelia with the LDM located in the upper thoracic and thoracolumbar regions, respectively. We previously partially reported an LDM patient with a syrinx and a flat lumbar skin lesion [4], and our recent additional two patients prompted us to report the detailed clinicopathological findings of terminal syringomyelia for all three patients with LDM. In this article, we discuss the pathophysiological mechanisms of the syrinxes in these three patients. ...
... We previously reported the findings in this 7-month-old girl with LDM with no extradural stalk linking to a flat skin lesion [4]. Intraoperatively, the intradural LDM stalk appeared to originate at the dural wall and join the cord. ...
... This finding suggests that the fluid in the hydromyelic central canal also distends the stalk of flat LDMs. A possible cause is that the presence of the stalk-cord attachment disturbs cerebrospinal fluid flow in the caudal side of the central canal [4]. The hydromyelic central canal might extend to the stalk-cord attachment, as in patient 2 ( Fig. 5 (b-1, b-2) and the rostral part of the LDM stalk, as in patient 3 (Fig. 5 (c-1, c-2). ...
Purpose
Limited dorsal myeloschisis (LDM) is characterized by a fibroneural tethering stalk linking the skin lesion to the underlying spinal cord. Terminal syringomyelia, which is located at the lower third of the cord, is often associated with a tethered cord caused by various spinal dysraphisms; however, terminal syringomyelia has not been documented in LDM. The purpose of this study was to clarify the pathophysiological mechanisms of syringomyelia in LDM.
Methods
In our 16 patients with lumbar LDM, three patients had terminal syringomyelia. We retrospectively analyzed the clinical, neuroradiological, intraoperative, and histopathological findings for these patients, with particular attention to the clinical course of the syrinx.
Results
Patient 1 had a saccular skin lesion and patients 2 and 3 had flat lesions. In all patients, the syringomyelic cavity was located in the lower thoracolumbar cord, immediately rostral to the stalk–cord attachment at the lumbar level. The caudal pole of the syrinx extended to the thickened stalk at the attachment instead of at the caudal cord. Patient 3 had another syrinx in the stalk itself. The longitudinal axis of the syrinx and central canal coincided with the traveling angle of the LDM stalk at the stalk–cord attachment. In patient 1, histology revealed an ependyma-lined central canal in both the LDM stalk and meningocele sac. Patients 1 and 2 underwent syringostomy, but long-term effects were not obtained. Preoperative spontaneous resolution occurred in patient 3.
Conclusions
The histological findings in patient 1 supported the idea that segmental myelocystocele is involved in the development of saccular LDM. The hydromyelic central canal herniates and distends the stalk, resulting in the formation of the myelocystocele. It is possible that the hydromyelic central canal also distends the stalk of flat LDM lesions. The syrinx in patient 3 differed from that in patients 1 and 2, in that the syrinx resolved spontaneously. Further studies are needed to clarify the outcomes of syrinxes associated with LDM stalks.
... In our case, furthermore, there was a tight anatomical relationship between the appendage and the stalk through the myofascial defect. The intervention of fibroadipose tissue does not contradict the LDM diagnosis, as our previous histological reports [4,8,9] demonstrated fibroadipose tissue between the skin lesion and stalk in many LDM patients, indicating that there is not always a tight fibrous connection. ...
Purpose
Limited dorsal myeloschisis (LDM) is characterized by a fibroneural stalk linking the skin lesion to the underlying spinal cord. On account of the external skin lesion, all LDMs are either flat (nonsaccular) or saccular, and a human tail-like cutaneous appendage has not been reported.
Methods
In our 14 LDM patients, 2 had tail-like appendages. We retrospectively analyzed the relationship between the appendage and the LDM tract from the clinicopathological findings of these 2 patients.
Results
Preoperative magnetic resonance imaging including three-dimensional heavily T2-weighted images demonstrated an intradural tethering tract, but failed to reveal the precise communication with the appendage. However, surgery revealed the extradural and intradural slender stalk, starting at the base of appendage and running through the myofascial defect. Histological examination demonstrated that there was a tight anatomical relationship between the fibroadipose tissue of the appendage and the fibrocollagenous LDM stalk.
Conclusion
When there is potential for an LDM stalk in patients with an appendage, a meticulous exploration of the stalk leading from an appendage is required. Clinicians should be aware of possible morphological variations of skin lesions associated with LDM.
The publication of a comprehensive report on limited dorsal myeloschisis by the senior author (DP) in 2010 has brought full attention to the concept of limited myeloschisis that he first formulated in 1992 and ignited interests in the whole spectrum of focal spinal nondisjunctional disorders. Now that focal nondisjunctional disorders have become well known, new clinical reports on these conditions or relevant subjects are frequently seen. Here we present an updated review on the full spectrum of focal spinal nondisjunctional disorders and extend the scope to include a discussion on the embryogenesis of cranial focal nondisjunctional malformations.KeywordsLimited dorsal myeloschisisDermal sinus tractDermoidNondisjunctionDysraphismFocal spinal nondisjunctional disordersFocal cranial nondisjunctional disordersEncephalocele
Limited dorsal myeloschisis (LDM), first proposed by Pang et al., is thought to originate from a small segmental failure of the dorsal closure of the neural folds during primary neurulation. The disjunction between the cutaneous and neural ectoderm is impaired at the focal limited nonclosure site. This results in a retained fibroneural stalk linking the skin lesion and the dorsal spinal cord, which results in tethering of the cord. Based on skin manifestations, LDMs were originally categorized as saccular and nonsaccular (flat). Saccular LDM consists of a skin-based cerebrospinal fluid sac topped by a squamous epithelial dome, whereas the flat LDM has a squamous epithelial flat surface or a sunken crater or pit typically called a “cigarette-burn” skin lesion. Recently, we reported a human tail-like cutaneous appendage as an additional morphological type of skin lesion. The recommended treatment consisted of prophylactic untethering of the stalk from the cord. Because of the shared origin of LDM and congenital dermal sinus (CDS), CDS elements may be found within the fibroneural LDM stalk with a 10-20% possibility. When part of the CDS invested in the intradural stalk is left during untethering surgery, inclusion tumors such as dermoid cysts may develop in the patient. Although the central histopathological finding of LDM stalk is the presence of glial fibrillary acidic protein (GFAP) -immunopositive neuroglial tissues in the fibrocollagenous tract, immunopositivity for GFAP was observed in 50-60% of pathologically examined cases. The presence of neural crest cells, such as peripheral nerve fibers and melanocytes, also assists in the histopathological diagnosis of LDM. In this case report, the diagnostic and surgical strategies of LDM are discussed accordingly.
