Brain biopsy samples showed prominent lymphocytic infiltration of the wall of small vessels; these findings in the beginning suggested small vessel CNS vasculitis, and both individuals were treated accordingly. did not relapse. Retrospective assessment of serum and CSF proven MOG antibodies in Cilnidipine both instances, and review of biopsy specimens showed absence of fibrinoid necrosis (a pathologic requirement for small vessel CNS vasculitis). Conclusions AntiCMOG-associated encephalitis can be mistaken for small vessel CNS vasculitis. This is important because the analysis of antiCMOG-associated encephalitis does not require brain biopsy and may be established having a serologic test. The analysis of small vessel main CNS vasculitis is definitely challenging because standard and mind MRI angiography are bad, and mind biopsy remains as the only definite diagnostic test.1 However, mind biopsy is invasive and may be uninformative because of sampling error. Here, we describe 2 individuals with myelin oligodendrocyte glycoprotein (MOG) antibodyCassociated encephalitis2 who have been in the beginning misdiagnosed with small vessel CNS vasculitis based on biopsy findings. Physicians should be aware of this potential misdiagnosis because it offers important medical implications. Case 1 A 5-year-old young man presented with 2 weeks of frontal headache and fever. His physical exam showed decreased alertness and bilateral papilledema (table). Mind CT and MRI (number 1A) were normal, and the CSF showed pleocytosis. Meningoencephalitis was suspected, and he was started on steroids and acyclovir. During the following days, he developed visual hallucinations. There was gradual medical improvement until total recovery, and the patient was discharged on steroid taper one month later on. In the ensuing 4 weeks, he was readmitted 3 times for relapsing symptoms while weaning from steroids. Repeat brain MRI showed T2 abnormalities in the basal ganglia, cerebellar peduncles, and supratentorial white matter (number 1B-D), and CSF pleocytosis was recognized in all episodes (table). All relapses considerably improved after treatment with steroids. In the last relapse, a conventional mind angiography was inconclusive. Mind biopsy showed infiltrates of lymphocytes involving the wall of small vessels and perivascular areas accompanied by perivascular demyelination (number 2ACD). The patient was diagnosed with main CNS vasculitis, and he was started on regular monthly pulses of cyclophosphamide. After the 5th pulse, he developed acute ideal optic neuritis that was treated with steroids, resulting in little Cilnidipine improvement. Considerable blood testing recognized an elevation of lipoprotein A (also present in his asymptomatic father), and oral aspirin was added, together with mycophenolate mofetil (MMF) and prednisone. He remained clinically and radiologically stable (number 1E), with a right vision visual deficit for 2 years; at this time, immunosuppression was weaned, and shortly after preventing the steroids (while on MMF and aspirin), he developed confusion and decreased level of consciousness. MRI showed considerable white matter abnormalities (number 1F) and high serum titer of MOG antibodies (1:640). Retrospective assessment of stored serum and CSF acquired at onset of the disease were also positive for MOG antibodies (serum titer 1:20,480 and CSF 1:320, table). Review of the paraffin block containing the brain biopsy showed that this inflammatory infiltrates were not confined to the vessel wall and also involved the white and gray matter. With these findings, the patient was diagnosed with Cilnidipine anti-MOG encephalitis, and treatment with rituximab, azathioprine, and low-dose prednisone was initiated. No more relapses were observed; at the last follow-up, 3 years later, he remained clinically and radiologically stable on azathioprine and low-dose prednisone (eventually discontinued), and the serum titer of MOG immunoglobulin G (IgG) antibodies had decreased (1:80) below the consensus limit of positivity (1:160).2,3 Table Clinical and laboratory data of 2 patients with anti-MOG encephalitis initially misdiagnosed with small CNS vessel vasculitis Open in a separate window Open in a separate window Open in a separate window Determine 1 MRI of 2 patients with anti-MOG encephalitis initially misdiagnosed with small vessel CNS vasculitisPatient 1: (A) Axial T2 MRI sequence showing no abnormalities at disease onset; (B) bilateral involvement of the basal ganglia 4 weeks after disease onset while steroids were being Cilnidipine decreased; Cilnidipine (C) left cerebral peduncle abnormality at 6-week follow-up; (D) asymmetric large hazy white matter and basal ganglia lesions at 4 months; (E) residual white matter lesions and enlargement of ventricles due to brain atrophy; and (F) new asymmetric large hazy white matter lesions 30 months after disease onset when steroids were discontinued. Patient 2: (G and H) Axial FLAIR sequences showing gyriform hyperintensities with edema similar to abnormalities previously reported in cases of antiCMOG-associated cortical encephalitis.6 Open in a separate Rabbit Polyclonal to GANP window Determine 2 Brain biopsy of 2 patients with anti-MOG encephalitis initially misdiagnosed with small vessel CNS vasculitisIn patient 1, biopsy of the right temporal lobe showed small vessel perivascular lymphocytic infiltration (A, hematoxylin-eosin staining; B, magnification of the vessel shown in panel A). Inflammatory infiltrates included T and B lymphocytes (not shown) in association with.