PMC7212842_01
(A-D) Preoperative magnetic resonance imaging (MRI). Enhancing lesion in the lateral ependymal surface of the right lateral trigone measuring 1.7 x 1.4 x 1.2 cm. The medial border is intimately associated with the adjacent choroid plexus. Surrounding vasogenic edema in the periventricular white matter of the right parietal lobe. (A-C) T1-weighted imaging post-gadolinium contrast representative axial, sagittal, and coronal images, respectively. (D) Representative axial T2 FLAIR image demonstrating perilesional edema. (E-H) Postoperative MRI following right parietal craniotomy for tumor resection. A small amount of residual postoperative fluid collection and associated dural thickening adjacent to the craniotomy site shown with the surgical tract leading toward the atrium of the right lateral ventricle. (E-G) Representative axial, sagittal, and coronal T1-weighted imaging post-gadolinium contrast images, respectively. (H) T2 FLAIR image demonstrating a decrease in perilesional edema compared to preoperatively.
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F1
Magnetic resonance imaging (MRI) with gadolinium showed a 1.7 x 1.4 x 1.2 cm enhancing tumor centered in the lateral ependymal surface of the right lateral trigone with associated vasogenic edema in the periventricular white matter of the right parietal lobe (Figure 1). This was stable at 1-year follow-up (Figure 1).
Pathological findings. (A) The tumor was composed of cells arranged in alternating dense fascicles and loose hypocellular areas (asterisks). (B) Areas of vague nuclear palisading were occasionally seen (arrowheads). (C) Tumor cells showed elongated nuclei with mild degenerative atypia. (D) Hyalinized vasculature (arrowhead) and perivascular hemosiderin-laden macrophages (arrows) were identified. (E) On immunohistochemistry, the tumor showed diffuse nuclear staining with SOX10 and (F) diffuse pericellular staining with collagen IV. Scale bars = 100 microm.
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F2
Histopathology showed a spindle cell neoplasm with alternating dense interweaving fascicles and looser hypocellular areas (Figure 2A). There were occasional areas of vague nuclear palisading (Figure 2B). Tumor cells had elongated nuclei with mild degenerative atypia (Figure 2C). Vasculature within the tumor was markedly hyalinized and there were abundant perivascular hemosiderin-laden macrophages (Figure 2D). Immunohistochemistry showed diffuse nuclear expression of SOX10 (Figure 2E) and cytoplasmic expression of GFAP. Diffuse pericellular staining was seen with collagen IV (Figure 2F).
Results of DNA methylation profiling analysis. (A) The top score from the DKFZ classifier v11b4 (Molecular Neuropathology, Heidelberg, Germany) suggests methylation class schwannoma as the most likely diagnosis based on methylation signature. (B) Chromosomal copy number variation profile generated from raw methylation data did not demonstrate any large-scale alterations, in keeping with schwannoma. (C and D) Unsupervised hierarchical clustering approach demonstrates that the tumor sample most closely clustered with schwannomas (vestibular and spinal) when strictly compared to meningiomas, gliomas, and choroid plexus tumors included. IDH_MUT, isocitrate dehydrogenase mutant; IDH_WT, isocitrate dehydrogenase wildtype; SS, spinal schwannoma; VS, vestibular schwannoma.
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F3
The top-ranked diagnosis was schwannoma (Figure 3A). Chromosomal copy number variation profile generated from raw methylation data did not demonstrate any large-scale alterations, in keeping with the diagnosis of schwannoma as opposed to other pathologies in the differential diagnosis (Figure 3B). Using unsupervised hierarchical clustering approaches, the tumor sample most closely resembled schwannomas when strictly compared to other tumors in the differential diagnosis (meningiomas, gliomas, and choroid plexus tumors; Figure 3C and D).