Balo Concentric Sclerosis BCS

Considered a variant of inflammatory demyelinating disease closely related to MS, BCS is characterized pathologically by large demyelinating lesions with a peculiar pattern of alternating layers of preserved and destroyed myelin, mimicking the rings of a tree trunk (Figure 12). Clinically, BCS resembles Marburg MS with similar acute fulminant onset followed by rapid progression to major disability and death within months (138,141,142). Of interest, one of the cases in Marburg's original series (case #3) contained extensive concentric lesions (138). Reports of less fulminant disease have been described (143,144), and smaller concentric rims of demyelination have been observed in lesions from some MS patients with a more classical acute or chronic disease course. T2-weighted MR images may reveal a distinct pattern of hypo-/isointense and hyperintense rings corresponding to bands of preserved and destroyed myelin and permit ante mortem diagnosis (143,145-150).

The etiology of the concentric demyelination in this variant of MS is unknown. Pathological evaluation of 12 autopsied patients with Balo-type concentric lesions demonstrated expression of i-NOS in macrophages and microglia in all active concentric lesions. A role for hypoxia in mediating tissue injury and contributing to lesion concentricity in BCS was suggested by the expressions of HIF-1a and heat shock protein 70 (hsp70) mainly in oligodendrocytes, and to a lesser extent in astro-cytes and macrophages at the edge of active lesions and in the outermost layer of preserved myelin (151). Due to their neuroprotective effects, the rim of periplaque tissue expressing these proteins may be resistant to further hypoxia-like injury in an expanding lesion, and therefore remain as a rim of preserved myelinated tissue.

Figure 12 (See color insert.) Spectrum of inflammatory demyelinating diseases. Marburg type multiple sclerosis: Macroscopically, confluent lesions lead to mass effect and herniation (A and B). Microscopically, there is extensive demyelination and axonal loss (C, LFB/PAS; D, Bielschowsky). Balo concentric sclerosis: Note the characteristic alternating bands of demyelination and preserved myelin (E). ADEM: The lesions are characterized by perivascular inflammation and only minimal, mainly perivenular demyelination (circles, F). Tumefactive lesion: Note with severe edema and mass effect (G). Creutzfeld-Peters cell: The presence of these cells should prompt consideration of an active demyelinating lesion (H). Abbreviations: LFB/PAS, luxol fast blue/periodic acid schif; ADEM, acute disseminated encephalomyelitis. Source: From Ref. 163.

Figure 12 (See color insert.) Spectrum of inflammatory demyelinating diseases. Marburg type multiple sclerosis: Macroscopically, confluent lesions lead to mass effect and herniation (A and B). Microscopically, there is extensive demyelination and axonal loss (C, LFB/PAS; D, Bielschowsky). Balo concentric sclerosis: Note the characteristic alternating bands of demyelination and preserved myelin (E). ADEM: The lesions are characterized by perivascular inflammation and only minimal, mainly perivenular demyelination (circles, F). Tumefactive lesion: Note with severe edema and mass effect (G). Creutzfeld-Peters cell: The presence of these cells should prompt consideration of an active demyelinating lesion (H). Abbreviations: LFB/PAS, luxol fast blue/periodic acid schif; ADEM, acute disseminated encephalomyelitis. Source: From Ref. 163.

0 0

Post a comment