PMC8769463_01
Preoperative and postoperative MRI and pathological findings. (A-C) Sagittal scan of the thoracic spine. An intradural tumor at Th5-8 level accompanied by syrinx cranial to the lesion was observed. The tumor showed hyperintensity in T2-weighted image (A), isointensity in T1-weighted image (B), and slight heterogeneous enhancement with contrast medium (C). (D and E) Axial scan of the thoracic spine. Spinal cord compressed in crescent shape, and at Th5 level the ventral part of the deformed spinal cord was involved into the tumor (D; arrow). (F-H) T2-weighted images of postoperative MRI (sagittal scan (F) and axial scans (G and H)). The tumor was completely resected, and compression of the spinal cord was improved with some residual deformity. (I and J) Microscopic view of the stained tissue specimens (hematoxylin & eosin). They showed perivascular pseudo-rosettes, which is a typical characteristic of ependymoma. (K and L) Immunohistochemical analysis of the specimens (GFAP (K) and MIB-1 (L)). GFAP-positive cells were observed especially in perivascular region (K). MIB-1 positive cells were exceptional (L).
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F1
MRI of thoracic spine revealed a solitary intradural tumor at Th5-8 level that showed iso-intensity in T1-weighed image and hyper-intensity in T2-weighed image compared with the spinal cord, and was slightly enhanced with Gd-DTPA (Fig. 1A-1C). The compressed spinal cord was deformed in crescent shape (Fig. 1D and 1E), and at Th5 level the ventral part of the deformed spinal cord was involved into the tumor and covering some part of the tumor as is the case of intramedullary tumor (Fig. 1D). A syringomyelia was found cranial to the lesion at Th2-4 level (Fig. 1A). The postoperative MRI showed total removal of the tumor and shrinkage of the syrinx (Fig. 1F-1H). Histological diagnosis was ependymoma (WHO grade 2) (Fig. 1I-1L).
Intraoperative view with microscope. (A) After completing laminectomy, the tumor compressing the spinal cord was directly observed without myelotomy. A yellow broken line indicates the tumor. (B) The tumor was grayish and easy to bleed. The lesion could be easily dissected from the spinal cord using various dissectors. (C) The tumor was completely resected.
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F2
Th4-9 (Fig. 2A). The extramedullary tumor was observed directly without myelotomy (Fig. 2B). The tumor was covered with the pia mater without any adhesion to the dura nor any connection to the nerve roots. Because dissection plane with the spinal cord was quite clear, microscopic total resection of tumor was achieved (Fig. 2C).
The schema of classification of intradural extramedullary ependymomas based on the tumor locations. All 32 axial images which were obtained from reviewed articles were listed in this figure. Tumors were classified into 10 medial type, 19 lateral type, and three dumbbell-shaped tumors. Ten medial type tumors were separated into four dorsal-medial type and six ventral-medial type tumors. Nineteen lateral type tumors were classified into nine dorsal-lateral type and four ventral-lateral type tumors, and remaining six tumors were difficult in defining dorsal or ventral. The number of attachment portion of each tumor was counted and listed in tables in the figure. N/A: not available.
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F3
Except for the cases of multiple lesions, in preoperative axial MRI images which were presented in 32 cases, the number of ventral lesions was almost equal to that of dorsal lesions (ventral: 10 and dorsal: 13), and six tumors located laterally and three were dumbbell-shaped tumors (Fig. 3). In 32 cases in which preoperative MRI axial images were available, operative findings were obtained in 26 cases (Fig. 3).