PMC6194731_01
Preoperative radiographic images. (a) Axial head computed tomography scan shows a round lesion, 2.5 cm in diameter, originating primarily from the right frontal dura mater. (b) Enhanced axial head computed tomography shows strong enhancement. (c) Head computed tomography angiography shows an apparent feeding artery (red arrow). (d) Contrast-enhanced axial magnetic resonance imaging shows a homogeneously enhanced extra-axial mass lesion. (e) Contrast-enhanced coronal magnetic resonance imaging shows enhanced extensive dural thickening around the tumor
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F1
The lesion showed isodensity without apparent calcification and hyperostosis [Figure 1a]. Intravenous administration of contrast media resulted in strong enhancement of the tumor and revealed an apparent feeding artery [Figure 1b and c]. Contrast-enhanced MRI revealed a homogeneously enhanced extra-axial mass lesion and enhanced extensive dural thickening around the tumor [Figure 1d and e].
Operative findings. (a) The tumor was soft and grayish. Dura mater adjacent to the tumor was thickened. Capillary blood vessels on the inner layer of the dura mater were dilated. (b) Arachnoid around the tumor was yellowish. It was partially difficult to exfoliate the tumor from brain parenchyma. (c) Successful removal of the tumor was achieved by frontal craniotomy. Most of the thickened dura mater remained. (d) Contrast-enhanced coronal magnetic resonance imaging shows complete resection of the tumor. Most of the enhanced dura mater was still present
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F2
The tumor was soft and grayish [Figure 2a], and the attached arachnoid was yellowish [Figure 2b]. The tumor was not partially easy to exfoliate from the brain parenchyma, but total removal was achieved [Figure 2c]. However, the dural tail could not be completely eliminated because the dura mater around the tumor was extensively thickened [Figure 2c and d]. Total resection of the tumor mass was confirmed by postoperative MRI [Figure 2d].
Histopathological findings. (a-c) Hematoxylin-eosin staining, (d-f) immunohistochemical analysis of IgG, CD138, and IgG4. (a) In most parts of the tumor, oval-shaped arachnoid-like cells were proliferating like sheets. Numerous eosinophils were diffusely observed in the tumor. Square area demarcates eosinophils at higher magnification (x20, magnification bar: 100 mum). (b) Dura mater was strongly thickened and capillary blood vessels were dilated. Eosinophils were not observed in the dura mater. Degenerated collagenous fibers were observed (x20, magnification bar: 100 mum). (c) An inflammatory reaction was observed in the arachnoid attached to the tumor as evidenced by a small number of eosinophils and nuclear debris (x20, magnification bar: 100 mum). (d) Diffuse IgG-positive cell infiltration was observed in the tumor (x20, magnification bar: 100 mum). (e) CD138 (also known as syndecan-1, SDC1) is a highly specific marker for terminally differentiated normal plasma cells. Diffuse CD138-positive cells infiltration was also observed in the tumor (x20, magnification bar: 100 mum). (f) Most of the CD138-positive plasma cells also expressed IgG4. Diffuse IgG4-positive plasma cell infiltration was observed in the tumor. The ratio of IgG/IgG4 was 70%. Square area demarcates IgG4-positive plasma cells at high magnification (x20, magnification bar: 100 mum)
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F3
In most parts of the tumor, oval-shaped arachnoid-like cells were proliferating like sheets [Figure 3a]. Numerous eosinophils and IgG4-positive plasma cells were diffusely observed in the tumor with IgG and CD138 expressions [Figure 3a and d-f]. The adherent dura mater was strongly thickened and capillary blood vessels were dilated, both of which were typically seen in the dural tail of a meningioma [Figure 3b]. IgG4-positive plasma cells were not observed in this thickened dura mater. Inflammatory signs were observed in the arachnoid, specifically a small number of eosinophils and scattered nuclear debris [Figure 3c].