Brain magnetic resonance imaging of preoperation shows an enhanced extraaxial mass-like lesion with adjacent subgaleal tissue thickening/enhancement, bony destruction in the right frontal area, dural thickening/enhancement, and leptomeningeal enhancement along the right cerebral convexity. (A) T2-axial, (B) precontrast T1-axial, and (C) postcontrast T1-axial images.|@|~(^,^)~|@|Histopathologic findings of tissue biopsy from scalp lesion. (A) Storiform fibrosis (yellow arrow) with destruction of the skull on H&E stain (×100). (B) Dense fibrosis and infiltration of inflammatory cells including lymphocytes, plasma cells and histiocytes on H&E stain (×200). (C) Increased immunoglobulin G4-positive cells (up to 68/high power field on immunoglobulin G4 immunohistochemistry stain) (×200).|@|~(^,^)~|@|Serial changes of serum acute phase reactants according to time. (A) Erythrocyte sedimentation rate (mm/h); (B) C-reactive protein (mg/dL). POD: postoperation day.

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