Visual Manifestations in the Setting of Perinuclear Antineutrophilic Cytoplasmic Antibody (P-ANCA) Vasculitis
Naga Pradyumna Kothapalli1, Heather Moss2, Shannon Beres3
1ophthalmology, 2ophthalmology and neurology/neurosciences, 3Ophthalmology and neurology/neurosciences, Stanford University
Objective:
To highlight the visual manifestations and imaging findings that could be encountered in the setting of P-ANCA/MPO vasculitis 
Background:
Antineutrophil autoantibodies (ANCAs) directed against myeloperoxidase (anti-MPO) are associated with a small vessel vasculitis in which the characteristic feature is a focal necrotizing damage of capillaries, venules and arterioles. It is known to cause optic nerve manifestations as primary pathology or secondary to meningeal inflammation causing raised intracranial pressure1. 
Design/Methods:
case report of two patients
Results:

Case 1:

A 49-year-old woman presented with painless left monocular vision loss. The examination revealed relative afferent pupillary defect in the left eye. Imaging (MRI brain) revealed enhancement of the left optic nerve sheath and diffuse enhancing dural thickening. Spinal fluid analysis revealed Lymphocytic pleocytosis and cytology/flow cytometry was negative for malignancy. Serum labs were positive for MPO-ANCA antibody. Biopsy of meninges revealed multifocal lymphoplasmacytic infiltration consistent with vasculitis. patient was diagnosed with MPO-ANCA- vasculitis and started on steroids. The patient improved clinically and radiographically with steroids later started on Rituximab.  

Case 2:  

A 62-year-old male presented with headaches and blurred vision. The examination revealed severe bilateral optic nerve head edema with hemorrhages around superior and inferior vessels. MRI of the brain revealed diffuse, enhancing dural thickening. Spinal fluid analysis showed pleocytosis with lymphocytic predominance and opening pressure of 30 cm H2O. Cytology and flow cytometry were negative for malignant cells. Serum labs showed positive MPO-ANCA antibody. Biopsy of meninges revealed fibrous tissue with inflammatory infiltrate. Patient was diagnosed with MPO-ANCA vasculitis due to clinical manifestations and started on steroids which resulted in significant improvement radiologically and clinically with resolution of papilledema and is now on Rituximab. 

Conclusions:
These cases highlight optic nerve involvement by MPO vasculitis, its radiologic features, and need to consider P-ANCA/MPO in the appropriate clinical setting.  
10.1212/WNL.0000000000204687