Primary Central Nervous System Vasculitis Mimicking Susac Syndrome and Multiple Sclerosis With Long-Term Remission and Spontaneous Resolution of Lesions: A Case Report

Abstract

Primary central nervous system vasculitis (PCNSV) is an angiitis localized to the central nervous system (CNS), with various manifestations and no specific biomarkers. Herein, we report a case of PCNSV that presented with an unusual course. A 40-year-old Japanese male developed inner ear symptoms and visual field disturbances. Later, at 42 years of age, the patient developed right hemiparesis and was diagnosed with multiple sclerosis (MS). He received methylprednisolone pulse therapy, which improved his symptoms and resolved most brain lesions. Subsequently, he did not visit the hospital for 13 years, during which time he experienced no relapse. At 55 years of age, he presented to our hospital with fatigue and dizziness. Susac syndrome was suspected because of sensorineural hearing loss and snowball lesions in the corpus callosum. Some of the brain lesions resolved spontaneously. A biopsy was performed on a right frontal lobe lesion, which revealed vasculitis with fibrinoid necrosis, no demyelinating lesions, no amyloid positivity, and no infiltration of atypical lymphocytes. With no evidence of vasculitis in other organs, the patient was diagnosed with PCNSV. The patient was treated with methylprednisolone pulse therapy, followed by oral prednisolone (1 mg/kg/day). The prednisolone was tapered off, and no relapse of symptoms or new lesions on magnetic resonance imaging (MRI) were noted. As observed in this case, even in a scenario suggestive of Susac syndrome or multiple sclerosis, PCNSV should be considered a differential diagnosis and confirmed via brain biopsy.

Keywords: biopsy; central nervous system vasculitis; long-term remission; multiple sclerosis; spontaneous resolution of lesions; susac syndrome.

Figure 1. Brain magnetic resonance imaging findings at the time of recurrence at the age of 42 years

FLAIR images show hyperintense lesions without contrast enhancement in the right medulla oblongata (A), left cerebellum (B), ventral side of the pons (C), right optic chiasm, bilateral putamen, left cerebral peduncle, subcortical white matter in the bilateral occipital lobe (D), right caudate nucleus, right globus pallidus, left thalamus, subcortical white matter in the left occipital lobe (E), and right splenium of the corpus callosum, subcortical white matter in the right frontal lobe and left parietal lobe (F), and a 20-mm-diameter rounded lesion in the subcortical white matter in the left parietal lobe (G). FLAIR images show no snowball lesions (H). FLAIR: fluid-attenuated inversion recovery

Figure 2. Brain and spinal cord magnetic resonance imaging findings on admission at the age of 55 years and before and after brain biopsy

T1-weighted image shows a hyperintense lesion in the right frontal lobe (A). Contrast enhancement is not observed in this lesion (B). T2* image shows a hyperintense lesion with scattered microhemorrhagic changes in the bilateral cortical and subcortical areas (C). FLAIR images show edematous lesions around the right frontal lobe lesion (D and E) and snowball lesions in the corpus callosum (F-H). On day X+21 before brain biopsy, FLAIR images show no change in the T1 and T2 hyperintense lesions in the right frontal lobe, but the surrounding edematous lesions are enlarged (I and J). We performed a brain biopsy of the lesion in the right frontal lobe (I) (arrow). Some snowball lesions in the corpus callosum have resolved, and some have decreased in size (K and L). On day X+76 after brain biopsy and before treatment, the edematous lesions around the right frontal lobe lesion are reduced on FLAIR images (M and N). The residual snowball lesions have resolved (O and P). Spinal cord magnetic resonance imaging showed no lesions (Q). FLAIR: fluid-attenuated inversion recovery

Figure 3. Histopathological findings of brain biopsy

Hematoxylin and eosin staining shows a hemorrhagic necrotic lesion surrounded by granulation including small vessels with fibrinoid necrosis (scale bar = 1 mm) (A). Hematoxylin and eosin staining (B) and Elastica van Gieson staining (C) show small vessels with fibrinoid necrosis scattered throughout the granulation tissue (scale bar = 100 μm). Arrow: small vessel with fibrinoid necrosis, arrowhead: hemorrhagic necrotic lesion