Department of Neuropathology, Hirosaki University Graduate School of Medicine, Hirosaki, Japan.
Neuropathology. 2013 Jun;33(3):281-7. doi: 10.1111/j.1440-1789.2012.01345.x. Epub 2012 Sep 19.
We describe an unusual case of myasthenia gravis. Our patient had been diagnosed as having myasthenia gravis with thymoma at the age of 64 years, and died of acute respiratory failure at the age of 80 years. Post mortem examination revealed CD8-positive lymphocytic infiltration with numerous giant cells in the skeletal muscles and myocardium. Immunohistochemical and ultrastructural studies revealed that there were two types of giant cells: histiocytic and myocytic in origin. Furthermore, both types of giant cells were immunopositive for proteins implicated in the late endosome and lysosome-protease systems, suggesting that endocytosis may be the key mechanism in the formation of giant cells. The present case, together with a few similar cases reported previously, may represent a particular subset of polymyositis, that is, giant cell polymyositis and myocarditis associated with myasthenia gravis and thymoma.
我们描述了一例重症肌无力的不典型病例。患者 64 岁时被诊断为合并胸腺瘤的重症肌无力，并于 80 岁时死于急性呼吸衰竭。尸检显示骨骼肌和心肌中有 CD8 阳性淋巴细胞浸润，伴有大量巨细胞。免疫组化和超微结构研究显示存在两种类型的巨细胞：组织细胞来源和肌源性。此外，两种类型的巨细胞均对涉及晚期内体和溶酶体蛋白酶系统的蛋白呈免疫阳性，表明内吞作用可能是巨细胞形成的关键机制。本病例以及之前报道的少数类似病例，可能代表了多发性肌炎的一个特殊亚群，即与重症肌无力和胸腺瘤相关的伴有巨细胞的多发性肌炎和心肌炎。
