 H&E stain Some patients have small angular fibers on H&E stain. These small fibers are often basophilic and have large nuclei (Right). |
 Gomori trichrome stain |
 NADH stain |
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The small muscle fibers stain darkly on Gomori trichrome & NADH.
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 ATPase pH 9.4 stain |
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The small muscle fibers with myosin loss have less staining than type I muscle fibers on ATPase pH 9.4 stain.
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Comparison of ATPase pH 9.4 (Left) & 4.3 (Right) in serial sections |
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Type I fibers (1): Darker staining at pH 9.4 than 4.3 Type II fibers (2): Darker staining at pH 4.3 than 9.4 Myosin loss fibers (0 or arrows): No staining at both pH 9.4 and pH 4.3 |
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 ATPase pH 9.4 stain |
 ATPase pH 4.3 stain |
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 H & E stain |
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 Myosin ATPase, pH 9.4 stain |
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A focal pattern of myosin loss may also occur in muscle fibers. Focal regions of myosin loss in type I and II muscle fibers. These regions appear basophilic on H & E stain. Myosin loss may occur in large as well as small fibers |
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 Anti-myosin antibody Reduced myosin in many small muscle fibers |
 Ultrastructure Thick filament loss with relative preservation of thin filaments & Z-lines |