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Brain Muscle |
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MELAS: Muscle fiber pathology |
Scattered abnormal, vacuolated fibers with clear rim: H & E |
Scattered "ragged red" muscle fibers: Gomori trichrome |
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Ragged red muscle fibers: Gomori trichrome
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Scattered muscle fibers with increased SDH staining |
Muscle fibers with variably increased levels of SDH staining |
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Muscle fiber with increased SDH staining: Individual mitochondria within muscle fiber are enlarged compared to surrounding fibers  |
Muscle fiber with mitochondrial proliferation Increased Sudan black staining  |
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Cytochrome Oxidase (COX) stain Muscle fibers may have reduced, normal or increased COX staining(Right) | |
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Muscle fibers with Mitochondrial proliferation (Increased SDH staining) Muscle fibers with increased SDH staining (Left) may have increased (Right) COX staining | |
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 Succinic dehydrogenase (SDH) stain |
 Cytochrome oxidase (COX) stain |
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MELAS: Mitochondrial staining of intramuscular vessels | |
 Succinic dehydrogenase (SDH) stain Increased SDH staining of a medium sized perimysial vessel in a MELAS patient. |
 Succinic dehydrogenase (SDH) stain Normal: Mild SDH staining of a medium sized perimysial vessel. |
Brain pathology in MELAS |
MRI during episode of hemiparesis
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 FLAIR image |
 T2 weighted image |
| CT during episode of homonymous hemianopia | |
 Medial occipital lesion (Arrow) |
 Enlarged ventricles |
Late in disease course
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MRI: Severe involvement of occipital cortex |
Severly abnormal temporal gray matter. Temporal horn of ventricles is enlarged. |