Rebai T, Mhiri C, Heine P, Charfi H, Meyrignac C, Gherardi R
Département de Pathologie (Neuropathologie), Hôpital Henri Mondor, Créteil, France.
Acta Neuropathol. 1989;79(2):226-32. doi: 10.1007/BF00294384.
Nerve biopsy in peripheral neuropathies associated with an IgM monoclonal gammopathy may occasionally display focal myelin thickenings. In a patient with such an IgM neuropathy, in whom an anti-myelin-associated glycoprotein (MAG) antibody activity was present in the serum, single-fiber preparations revealed 34% of internodes bearing myelin swellings. The morphometric, morphological and ultrastructural findings were reminiscent but not identical to those of the hereditary tomaculous neuropathy with liability to pressure palsies. Atypical features for tomacula included lack of spiralization of the redundant loops of myelin around the axons and their predominant external situation with regard to the myelin sheath. The frequent colocalization of myelin thickenings and the widening of myelin lamellae typical of IgM neuropathies, are highly suggestive of some pathogenetic link between the two abnormalities. The redundant loops of myelin in IgM neuropathies possibly result from a defect in the axon-myelin adhesion secondary to the binding of IgM on an epitope of MAG directly involved in cell-cell adhesion.
与IgM单克隆丙种球蛋白病相关的周围神经病患者的神经活检偶尔可显示局灶性髓鞘增厚。在一名患有此类IgM神经病且血清中存在抗髓鞘相关糖蛋白（MAG）抗体活性的患者中，单纤维标本显示34%的结间段有髓鞘肿胀。形态学、形态计量学和超微结构的发现使人联想到遗传性压力易感性神经病，但并不完全相同。典型的髓鞘瘤的非典型特征包括围绕轴突的多余髓鞘环缺乏螺旋化以及它们相对于髓鞘的主要外部位置。IgM神经病典型的髓鞘增厚和髓鞘板层增宽的频繁共定位，强烈提示这两种异常之间存在某种致病联系。IgM神经病中多余的髓鞘环可能是由于IgM与直接参与细胞间粘附的MAG表位结合后轴突-髓鞘粘附缺陷所致。
