PMC8053431_01
(a) Photograph showing a subcutaneous mass (yellow arrows) on the right side of the gluteal cleft which deviates to the left. Another groove is noted at the rostral side of the gluteal cleft (blue arrow). (b-d) Sagittal views (slice thickness of 1.25 mm) of three-dimensional heavily T2-weighted image (3D-hT2WI) (b) and three-dimensional T1-weighted spoiled gradient-recalled echo image (3D-T1WI) (c) and axial views (slice thickness of 5.2 mm) of T2-weighted image (T2WI) depict that the caudal spinal cord remains thick with minimal tapering (b, c, d-1-5) and, with minimal increase in diameter, extends as a cord-like structure (C-LS) to the dural cul-de-sac at the L3-4 vertebral level (b, c, and d-6-9). (e) Axial views (slice thickness of 5.2 mm) of 3D-T1WI demonstrate that lipoma is associated with the right half of the C-LS (e1-3). The extradural C-LS is located in the center of the epidural fat (e-4). (f) Schematic drawing and (g) microscopic view of the operative findings and (h) intraoperative neurophysiological monitoring (IONM). A lineal skin incision was made on the mid-lumbosacral region (f-1). Laminoplastic laminotomy of L4-bifid S2 revealed that the caudal spinal cord and C-LS extended to the dural cul-de-sac without an intervening terminal filum (f-2, g-1). The lipoma was observed at the right side of the C-LS below L5-S1 level. The border between the true cord and C-LS was determined with IONM, by tracing the evoked compound muscle action potentials (CMAPs) of the external anal sphincter with stimulation of 1 mA (h), beginning from the functional cord (h-(1)(2)(3)) and proceeding to the to the nonfunctional CL-S (h-(4)(5) (6)). Stimulation sites are indicated on (f-2) and (g-1). The C-LS with lipoma was severed at this border and most caudal side of the operative field and resected as a column (f-3). The lipoma was minimally debulked and the pial surface was reconstructed with sutures (f-4, g-2). (i-k) Photomicrograph of cross-sections of the C-LS including lipoma with hematoxylin and eosin staining (HE) (i,k) and immunostaining for glial fibrillary acidic protein (GFAP) (j). The location of section is indicated as red line in (f-3) and the orientation is almost matched with that of (e-2). A higher magnification view of the area is indicated by the dotted square in (i) and (j). The C-LS, which consists of fibrocollagenous tissue (FCT) embedding a central canal (CC)-like structure lined by ependymal cells (Epen) and surrounded by GFAP immunopositive neuroglial tissues, is located on the left side of the resected column. The lipoma, which consists of a mature fibroadipose tissue (FAT), is located on the right side of the C-LS. Original magnification: (i) x4, (j) x40, and (k) x200.
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F1
His gluteal cleft deviated to the left due to the subcutaneous mass [Figure 1a]. Magnetic resonance images (MRI) demonstrated that the caudal spinal cord remained thick with minimal tapering and, with a minimal increase in diameter, extended as a C-LS to the dural cul-de-sac at the S3-4 vertebral level [Figure 1b-d]. Lipomatous tissue was associated with the right half of the C-LS [Figure 1c, e1-3]. The epidural C-LS was located at the center of the epidural fat [Figure 1e-4]. The border between the true cord and C-LS was determined with IONM, by tracing the evoked compound muscle action potentials of the legs and anus with stimulation, beginning from the functional cord [Figure 1h-(1)(2) and  (3)] and proceeding to the nonfunctional C-LS [Figure 1h(4)(5) and  (6)]. The C-LS with the lipoma was severed at this border and at the caudal most side of the operative field, and it was resected as a column [Figure 1f-3]. Histopathological examination revealed that the C-LS, which consisted of fibrocollagenous tissue embedding a central canal-like structure lined by ependymal cells and surrounded by glial fibrillary acidic protein (GFAP)-immunopositive neuroglial tissues, was located on the left side of the resected column [Figure 1i-k].
(a) Photograph showing an abnormal Y-shaped groove and another groove, continuous from the gluteal cleft. (b-g) Preoperative images. Sagittal views (slice thickness of 1.25 mm) of 3D-hT2WI (b) and 3DT1WI (c) at 26 days of age, and sagittal views (slice thickness of 1.25 mm) of 3D-hT2WI (d) and 3DT1WI (e) and axial views (slice thickness of 3.9 mm) of T2WI (f) and T1-weighted image (g) at 3 months of age depict that the caudal spinal cord and continuous C-LS, with a large syringomyelia cyst at the L5-S2 level, extends to the dural culde-sac at the S2-3 level. The caudal and right half of the cyst wall is lipomatous tissue, which became more evident on the 2nd MRI. A sacral perineural cyst is also noted. (h-j) Schematic drawing (h) and microscopic view of the operative findings (i) and IONM (j). A lineal skin incision was made on the mid-lumbosacral region (h-1). Laminoplastic laminotomy of L5-S3 revealed that the caudal spinal cord and C-LS, including the cyst, extended to the dural cul-de-sac without an intervening terminal filum (h-2, i-1). The cyst wall and the lipomatous tissue were observed at the right and caudal side of the C-LS, respectively. IONM, by tracing the evoked CMAPs of the external anal sphincter with stimulation of 0.5 mA, failed to determine the border between the true cord and C-LS, while the amplitude of CMAPs tended to decrease toward the caudal side (j(1)-(6)), probably due to the current spread through the small nerve roots, which were tightly adhered to the ventral surface of the cord and C-LS (i-2). The lipoma with C-LS was severed at the caudal part and elevated (h-3). A small amount of water-like clear fluid flowed out from the cyst and the cyst was collapsed. After confirming nonfunctional C-LS and lipoma with IONM (j(7)(8)), the caudal part of the C-LS along with lipoma was resected as a column (h-4). The lipoma was minimally debulked to enlarge the cyst orifice and make a decent stoma for cystostomy (h-5, i-4). The caudal remnant lipoma was minimally debulked and the pial surface was reconstructed with sutures. No direct surgical procedure for sacral perineural cyst was performed. (k-q) Photomicrograph of cross-sections of the C-LS including lipoma with HE (k,m,p) and immunostaining for GFAP (l,n,o,q). The location of section is indicated as red line in (h-4) and the orientation is almost matched with that of (g-3,4). A lower or higher magnification view of the area is indicated by the dotted square in (k), (m), and (p). The C-LS, which consists of fibrocollagenous tissue embedding a central canal-like structure lined by ependymal cells and surrounded by GFAP-immunopositive neuroglial tissues, is located on the right side of the resected column. The lipoma, which consists of a mature fibroadipose tissue, is located on the left side of the column. Central canal-like structure decreased in size, moving caudally. *Indicates the destruction of the cyst wall created when preparing the specimen. Original magnification: (k-q) x4 and (o) x20.
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F2
At birth, abnormal grooves continuous from the gluteal cleft were noted [Figure 2a]. MRIs, at 26 days [Figure 2b and c] and 3 months [Figure 2 d-g] of age, demonstrated that the caudal spinal cord and continuous C-LS, with a large syringomyelia cyst at the L5-S2 level, extended to the dural cul-de-sac at the S2-3 level. IONM failed to determine the border between the true conus and C-LS [Figure 2j(1)-(6)], probably because of the current spread through the small but functional nerve roots, which tightly adhered to the ventral surface of the cord and C-LS [Figure 2i-2]. The C-LS with the lipoma was severed near the dural cul-de-sac and elevated to separate the nerve roots from the C-LS [Figure 2h-3]. After confirmation of a nonfunctional C-LS with IONM [Figure 2 j(7) and  (8)], the caudal part of the C-LS along with the lipoma was resected as a column [Figure 2 h-4]. Histopathological examination revealed that the C-LS was located on the right side of the resected column [Figure 2k, and  l]. The central canal-like structure with surrounding neuroglial tissues and fibrocollagenous tissues was caudally continuous, but its size decreased toward the caudal side [Figure 2 m-q].
PMC8053431_02
(a) Photograph showing an abnormal Y-shaped groove and another groove, continuous from the gluteal cleft. (b-g) Preoperative images. Sagittal views (slice thickness of 1.25 mm) of 3D-hT2WI (b) and 3DT1WI (c) at 26 days of age, and sagittal views (slice thickness of 1.25 mm) of 3D-hT2WI (d) and 3DT1WI (e) and axial views (slice thickness of 3.9 mm) of T2WI (f) and T1-weighted image (g) at 3 months of age depict that the caudal spinal cord and continuous C-LS, with a large syringomyelia cyst at the L5-S2 level, extends to the dural culde-sac at the S2-3 level. The caudal and right half of the cyst wall is lipomatous tissue, which became more evident on the 2nd MRI. A sacral perineural cyst is also noted. (h-j) Schematic drawing (h) and microscopic view of the operative findings (i) and IONM (j). A lineal skin incision was made on the mid-lumbosacral region (h-1). Laminoplastic laminotomy of L5-S3 revealed that the caudal spinal cord and C-LS, including the cyst, extended to the dural cul-de-sac without an intervening terminal filum (h-2, i-1). The cyst wall and the lipomatous tissue were observed at the right and caudal side of the C-LS, respectively. IONM, by tracing the evoked CMAPs of the external anal sphincter with stimulation of 0.5 mA, failed to determine the border between the true cord and C-LS, while the amplitude of CMAPs tended to decrease toward the caudal side (j(1)-(6)), probably due to the current spread through the small nerve roots, which were tightly adhered to the ventral surface of the cord and C-LS (i-2). The lipoma with C-LS was severed at the caudal part and elevated (h-3). A small amount of water-like clear fluid flowed out from the cyst and the cyst was collapsed. After confirming nonfunctional C-LS and lipoma with IONM (j(7)(8)), the caudal part of the C-LS along with lipoma was resected as a column (h-4). The lipoma was minimally debulked to enlarge the cyst orifice and make a decent stoma for cystostomy (h-5, i-4). The caudal remnant lipoma was minimally debulked and the pial surface was reconstructed with sutures. No direct surgical procedure for sacral perineural cyst was performed. (k-q) Photomicrograph of cross-sections of the C-LS including lipoma with HE (k,m,p) and immunostaining for GFAP (l,n,o,q). The location of section is indicated as red line in (h-4) and the orientation is almost matched with that of (g-3,4). A lower or higher magnification view of the area is indicated by the dotted square in (k), (m), and (p). The C-LS, which consists of fibrocollagenous tissue embedding a central canal-like structure lined by ependymal cells and surrounded by GFAP-immunopositive neuroglial tissues, is located on the right side of the resected column. The lipoma, which consists of a mature fibroadipose tissue, is located on the left side of the column. Central canal-like structure decreased in size, moving caudally. *Indicates the destruction of the cyst wall created when preparing the specimen. Original magnification: (k-q) x4 and (o) x20.
SNI-12-112-g002.jpg
PMC8053431_02_SNI-12-112-g002.jpg
F2
At birth, abnormal grooves continuous from the gluteal cleft were noted [Figure 2a]. MRIs, at 26 days [Figure 2b and c] and 3 months [Figure 2 d-g] of age, demonstrated that the caudal spinal cord and continuous C-LS, with a large syringomyelia cyst at the L5-S2 level, extended to the dural cul-de-sac at the S2-3 level. IONM failed to determine the border between the true conus and C-LS [Figure 2j(1)-(6)], probably because of the current spread through the small but functional nerve roots, which tightly adhered to the ventral surface of the cord and C-LS [Figure 2i-2]. The C-LS with the lipoma was severed near the dural cul-de-sac and elevated to separate the nerve roots from the C-LS [Figure 2h-3]. After confirmation of a nonfunctional C-LS with IONM [Figure 2 j(7) and  (8)], the caudal part of the C-LS along with the lipoma was resected as a column [Figure 2 h-4]. Histopathological examination revealed that the C-LS was located on the right side of the resected column [Figure 2k, and  l]. The central canal-like structure with surrounding neuroglial tissues and fibrocollagenous tissues was caudally continuous, but its size decreased toward the caudal side [Figure 2 m-q].