失敗しない筋病理標本の作りかた読みかたのエッセンス

抄録

In the diagnosis of muscle diseases, “muscle pathology” still plays a clinical important role in the present, although a large number of causative genes and myositis–specific autoantibodies have been discovered. Actually, many muscle diseases are defined based on muscle pathology. Muscle pathology provides many useful information for differentiation of inclusion body myositis in the diagnosis of idiopathic inflammatory myopathy. Muscle pathology is connected directly with a diagnosis name for congenital myopathy. Because some breakthrough therapies are developed in variable muscle diseases, the significance of diagnosis confirmation of muscle diseases increases more and more. However, muscle biopsy should not be performed in all cases. We should judge the indication of muscle biopsy exactly.

It is necessary that we take biopsy specimens from the appropriate site of the muscle in the appropriate facilities. In addition, proper handling and fixation of biopsy specimens are necessary to avoid artifacts. We should select muscles biopsy sites and perform an appreciate muscle biopsy procedure. Skeletal muscle MRI and electromyogram are useful for the decision of the biopsy site. We should appropriately freeze and fix the muscle specimens collected, because histochemistry and immunohistochemistry are required.

The most important stains are hematoxylin & eosin, modified Gomori–trichrome, and NADH–TR. With these three staining techniques, judgements about basic pathological findings can be made and lead to the definitive diagnosis in many muscle diseases. If necessary, other various kinds of histochemistry including myosin ATPase, cytochrome C oxidizing enzyme, succinic acid dehydrogenase, and PAS may be requested. In the present, immunohistochemistry stains against dystrophin, sarcoglycans, dysferlin, laminin–α2, α–dystroglycan, emerin, and collagen–6 are very significant for the definitive diagnosis of many muscular dystrophies. Similarly, immunohistochemical evaluations of MHC class I/II in muscle fibers and CD4/CD8 expression on infiltrating T cells are important for the definitive diagnosis of inflammatory myopathies.