PMC4086335_01
Imaging characteristics: (a) head CT scan, axial projection, and osteolytic defect in the right frontal area in the location of the bone tumour; (b) head CT scan, axial projection, bone window, and osteolytic defect in the right frontal area; (c) MR of the brain, axial projection, T1 SE, and the area of mixed signal intensity inside the bone in the right frontal area; (d) MR of the brain, image in the sagittal plane, and T2 FSE hyperintense area in the right frontal area; (e) MR of the brain, image in the coronal plane, and T2 FSE, hyperintense area in the right frontal area; (f) MR of the brain, image in the coronal projection, T1 following the application of contrast agents, and contrast enhancement features involving only the bone structure.
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fig1
The CT examination suggested an eosinophilic granuloma (Figures 1(a)-1(b)). The MR (magnetic resonance) imaging showed irregular areas of an increased signal intensity on the T2 weighted image in the area of the calvaria and a mixed signal intensity on the T1 weighted image, with contrast-enhanced features, involving only the structure of the bone (Figures 1(c)-1(f)).
Operative specimen. The internal surface of the bone flap removed with the tumour. The area of the tumour located inside the osteolytic defect of the bone with the adhering part of the dura mater marked with dots.
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fig2
After removing the bone flap, a lesion localized inside the bone and adjacent to the dura mater was discovered (Figure 2).
Histopathology: (a) H-E, photomicrograph, original magnification 400x, fragment of the surgically removed tissues, and numerous microcysts containing a pale eosinophilic fluid, surrounded by processes of neoplastic cells; (b) Ki-67, when it is positive in singular cells, it points to very low proliferative activity of the neoplasm, photomicrograph, original magnification 400x, and fragment of the surgically removed tissues; (c) EMA (+), photomicrograph, original magnification 400x, and fragment of the surgically removed tissues; (d) CK (+), photomicrograph, original magnification 400x, and fragment of the surgically removed tissues.
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fig3
The microcystic variant of meningioma was diagnosed (Figures 3(a)-3(d)).