Baló’s concentric sclerosis (BCS) is a rare demyelinating disease, histopathologically characterized by large concentric lesions with rings of myelin loss alternating with rings of myelin preservation; BCS is considered to be more consistent with pattern III Multiple Sclerosis (MS) lesions in neuropathological studies. The typical MRI finding of BCS is a tumefactive brain lesion with hyperintense-isointense-hypointense concentric rings on T2-weighted images; however other typical lesions for MS can also be observed. Regarding treatments there are no established algorithms yet.
To present a group of patients with BCS and introduce the concept of distinct BCS subtypes with different response to therapies.
Retrospective clinico-radiologic analysis of 10 treated patients with a tumefactive (size ≥ 2cm) BCS lesion at first clinical attack, diagnosed from 2009 to present. Mean age at onset was 25.6 years (range 18-41) and mean follow-up was 50 months (range 2-136).
In our cohort the mean BCS lesion size was 2.763cm. All patients received induction therapy with high doses of intravenous methylprednisolone (IVMP) at symptom onset and 9 out of 10 continued with maintenance treatment. According to radiological characteristics and response to therapies we categorized them into 4 subtypes : i) solitary BCS tumefactive lesion ; 2 patients non-responders to IVMP, one of the two with significant reponse following i.v. cyclophosphamide, ii) BCS lesion with coexisting non-specific brain lesions; 3 patients with poor response to IVMP but with remarkable response to immunosupression (cyclophosphamide n=2, mitoxantrone n=1), iii) BCS lesion with typical MS lesions; 2 patients that responded initially to IVMP and followingly to natalizumab, iv) BCS lesion with coexistence of another demyelinating tumefactive lesion; 3 patients moderate responders to IVMP but with excellent clinicoradiologic outcomes under rituximab.
We described 4 distinct subtypes of Balo successfully treated with different immunotherapies; after high doses of i.v. corticosteroids, maintenance therapy should be decided according to the specific subtype. Immunosupression with cyclophosphamide or mitoxantrone seems to be an effective choice, however the use of immunomodulatory MS drugs or cell depletion therapies should also be considered in BCS cases where MS characteristics are also present.