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Capillary pathology Alkaline phosphatase Complement deposition Inflammation Perifascicular atrophy Adult pattern |
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Muscle fiber atrophy: Perifascicular distribution![]() H&E stain |
![]() H&E stain |
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Muscle fibers near the perimysium are small but not necrotic. Necrotic fibers are more common in adult forms of DM. Nuclei in small muscle fibers are enlarged and occasionally internal. |
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![]() Batten FE Br J Child Dis 1912;9:247 |
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Other stains showing perifascicular pathology | ||
![]() ATPase pH 9.4 stain |
![]() Cytochrome oxidase stain |
![]() NADH stain |
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Perifascicular atrophy is often most prominent on ATPase stains |
The extent of the perifascicular muscle pathology in active DM is often most prominent on cytochrome oxidase stain. Perifascicular muscle fibers have reduced staining more commonly in children. |
Muscle fibers near the perimysium are small & stain somewhat darkly |
Alkaline phosphatase staining: Other vascular & connective tissue pathology |
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Alkaline phosphatase may stain several different structures
in patients with dermatomyositis. | ||
![]() Alkaline phosphatase stain |
![]() Alkaline phosphatase stain |
![]() Alkaline phosphatase stain |
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Perimysium Vascular staining. More common in children |
Endomysium Capillary staining, especially in perifascicular regions. |
Perimysium Diffuse staining. More common in adults Rare in children |
![]() Stain: Ulex europaeus agglutinin I Dermatomyositis: Capillaries are enlarged and reduced in number Changes are patchy and most prominent in perifascicular regions |
![]() Stain: Ulex europaeus agglutinin I Control: Capillaries are abundant and small |
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![]() Stain: C5b-9 components of complement (Membrane attack complex) Dermatomyositis: C5b-9 deposition in endomysial capillaries Changes are patchy and most prominent in perifascicular regions |
Normal control![]() Stain: C5b-9 components of complement (Membrane attack complex) No C5b-9 deposition in endomysial capillaries |
![]() Stain: MHC Class I Normal: MHC I staining only on capillaries |
![]() Stain: MHC Class I Dermatomyositis: MHC I upregulation on the surface and within muscle fibers |