FOCAL LESIONS AREA FEATURE OF CHRONIC INFLAMMATORY DEMYELINATING POLYNEUROPATHY (CIDP)

In a study designed to identify the neuropathological features typical of chronic inflammatory demyelinating polyneuropathy (CIDP), we revie wed the sural nerve biopsy findings in 105 patients with this disorder . The patients' mean age at biopsy was 49 years. In 65% of patients th e disease had a progressive and in 35% a relapsing-remitting course. I n 47% of cases the disorder was idiopathic; the remainder had various concurrent conditions. All sural nerve biopsy specimens showed varying amounts of active demyelination associated with onion bulbs (48% of c ases), endoneurial edema (55%) and inflammatory infiltrates (25%). The immunopathological hallmarks were T cell infiltration with macrophagi c activation and up-regulation of major histocompatibility complex (MH C) class II expression, without B cell infiltration or immunoglobulin deposition on myelin sheaths. In 30% of cases some myelin sheaths show ed C3d deposition. Analysis of proinflammatory cytokine expression inv ariably showed interleukin-1 in perivascular and endoneurial ramified cells and tumor necrosis factor-alpha prevalently in epineurial macrop hages, whereas it detected interferon-gamma only in samples with periv ascular inflammatory cells. This immunological pattern suggests that t he cellular components of immunity play the major role in CIDP. In 19% of cases the neuropathological changes had a focal distribution. This distinctive feature corresponded to more active demyelination, more f requent detection of inflammatory infiltrates and more prominent immun ological activation, suggesting that focal involvement is a possible s tep in the course of the disease.