To describe clinical, radiologic, and pathologic features of Baló concentric sclerosis (BCS) and assess overlap between BCS and other CNS inflammatory demyelinating diseases.
Retrospective review of BCS cases from US and Australian tertiary care centers.
We identified 40 BCS cases with 38 available MRIs. Solitary MRI lesions were present in 26% (10/38). We saw >1 active concurrent BCS lesion in 45% (17/38). A third (13/38) had multiple sclerosis–suggestive lesions on the index MRI, of which 10 fulfilled Barkhof criteria. In patients with serial MRI performed within 1 month of the index MRI, lesions expanded radially with sequentially increased numbers of T2 hyperintense rings 52% (14/27). Initially nonenhancing or centrally enhancing lesions subsequently developed single or multiple enhancing rings (41%; 9/22) and incomplete enhancing rings (14%; 3/22). Discordance between rings as they appear on apparent diffusion coefficient, diffusion-weighted imaging, and gadolinium-enhanced imaging was observed in 67% (22/33). Aquaporin-4 immunoglobulin G (n = 26) and myelin oligodendrocyte glycoprotein immunoglobulin G (n = 21) were negative in all patients with serum available. Clinical response to steroid treatment was seen in 46% (13/28). A monophasic clinical course was present in 56% (18/32) at last follow-up (median 27.5 months; range 3–100 months). The initial attack was fatal in 10% (4/40). Median time from symptom onset to death was 23 days (range 19–49 days). All 17 patients with pathology available demonstrated typical findings of multiple sclerosis. Patients with active demyelinating lesions all demonstrated oligodendrocytopathy (pattern III).
BCS may be a distinct subtype of multiple sclerosis characterized by pattern III immunopathology.