Granulomatosis with polyangiitis with fourth ventricular mass, choroid plexitis, and hypophysitis: a case report

Granulomatosis with polyangiitis (GPA) is an antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis affecting small to medium-sized arteries uncommonly involving the central nervous system (CNS) with cerebral vasculitis, meningitis, and orbital granuloma. Here we report a rare case with GPA with a fourth ventricular mass lesion, choroid plexitis, and hypophysitis. A 46-year-old male presented with subacute headache, fevers, hemoptysis, nausea, vomiting, ataxia, blurred vision, hearing loss, and excessive thirst. He was diagnosed with GPA six years prior and was not on any disease-modifying therapy due to personal preferences. Computed Tomography (CT) of the chest revealed a pulmonary embolism (PE) and multifocal cavitary lung lesions. Cranial Magnetic Resonance Imaging (MRI) revealed a heterogeneously enhancing, enlarged pituitary gland with thickening of the pituitary infundibulum concerning for hypophysitis, in addition to a heterogeneously enhancing mass within the fourth ventricle with signal abnormality in the adjacent brainstem and brachium pontis. Serum and urine studies were consistent with central diabetes insipidus (CDI). The fourth ventricular mass was resected and histopathology showed remnant choroid plexus with vasculitis, necrosis, and mixed inflammatory infiltrate including multinucleated giant cells, consistent with GPA involvement of the fourth ventricular choroid plexus. The patient improved with steroid treatment, desmopressin for CDI, and anticoagulation for PE. After discharge he was treated with rituximab, prednisone, and subsequent addition of mycophenolate mofetil, achieving stable control of his symptoms. GPA can rarely present as a mass-occupying CNS lesion and should be considered with multidisciplinary and histopathologic evaluation for possible immunosuppressive treatment.