Pathology: Early; During attacks of weakness
H & E and NAHD stains
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Vacuoles: Evolution
- Non-vacuolated regions
- T-tubule system: Dilated & Proliferating
- Sarcoplasmic reticulum: Dilated; Contains amorphous material; Surrounded by glucogen
- Evolving vacuoles
- Appearance: Rarefaction
- Stain for NADH & Acid phosphatase
- Poorly demarcated
- Contain amorphous material & Multiple small vacuoles
- Intermediate vacuoles
- Well demarcated
- Contain amorphous matrix ± Calcified SR vesicles
- Mature vacuoles
- Limited by membrane: Stabilized by cytoskeletal proteins
- Contain fine granular material
- Remodeled vacuoles
- Mature vacuoles containing sarcoplasmic invaginations with glycogen granules
- Ruptured vacuoles: May produce muscle fiber necrosis
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Pathology: Late; During permanent weakness
- Internal architecture: Vacuoles;
Tubular aggregates
- Chronic myopathic changes
- Split fibers
- Varied muscle fiber size
- Internal nuclei
- Endomysial connective tissue: Increased
H & E stain
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