Granulomatosis with Polyangiitis Presenting with Thrombovasculitic and Necrotizing Pachy- and Leptomeningitis Accompanied by a Brain Tumor-like Lesion

We report a case of granulomatosis with polyangiitis (GPA) presenting with hypertrophic pachymeningitis with a huge brain tumor-like lesion. A 57-year-old man acutely developed consciousness disturbance. Magnetic resonance imaging revealed a right frontal lobe mass with thickened, contrast-enhanced dura. Computed tomography revealed sinusitis and multiple lung nodules. The presence of proteinase 3-anti-neutrophil cytoplasmic antibody indicated GPA. Histopathology of the excised brain tissues revealed thrombovasculitis with heavy neutrophilic infiltration in the pachy- and leptomeninges covering an ischemic cerebral cortex. The patient improved with corticosteroids and rituximab. Our case warrants considering GPA as a cause of hypertrophic pachymeningitis with brain-tumor like lesions.