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![]() Segmental Necrosis of Muscle fibers: Varied stages
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Cell & Metabolic Conparative features Morphology Dark Metabolic failure Membrane damage Large Histiocyte Phagocytosis |
Necrosis, Early Stages: Muscle Fiber Patterns of Pathology |
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![]() Myofiber Necrosis Metabolic Muscle Fiber cytoplasm Pale stain: Diffuse Myonuclei: Lose staining |
![]() Myofiber Necrosis Sarcolemmal Membrane Δ Muscle Fiber Cytoplasm Pale stain: "C" or Δ Lesion Dark stain: Around C-region Myonuclei: Lose staining |
![]() Myofiber Necrosis Dark Necrosis Muscle Fiber Cytoplasm Dark stain: Diffuse Myonuclei: Lose staining |
![]() Myofiber Necrosis Histiocyte-Associated Neighboring histiocytes Around edge of fiber Muscle Fiber Cytoplasm Stain: Present |
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Later Stages: Histiocyte Invasion & Phagocytosis of Muscle fibers |
Later stage: Fiber Degeneration | |||
![]() Myofiber Necrosis Cell invasion Stage: Intermediate Muscle Fiber Macrophage invasion |
![]() Myofiber Necrosis Phagocytic Stage: Late Muscle Fiber No cytoplasm remaining Replaced by histiocytes |
![]() Myofiber Necrosis Collapse Stage: Very Late Muscle Fiber Space: Collapsed Histiocytes Few remaining Many have migrated away |
![]() Myofiber Necrosis Primary Fiber Degeneration Stage: Late Muscle fiber Cytoplasm: Fragmented; Lost Histiocytes: Few or None |
Differential Diagnosis: Myofiber Necrosis in Immune Myopathies |
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Syndrome | Myofiber Pathology |
Pathology Other Tissues |
Immune cells/ Location |
Antibody (Serum) | IIM Clinical Syndromes |
LHIM | Necrosis: Scattered |
None | Histiocytes/ Near myofibers |
No | Necrotic Myopathy |
IMPP | Necrosis: Perifascicular |
Perimysium Damage |
Histiocytes/ Perimysium |
tRNA synthetase (Jo-1) HMGCR |
DM/PM/NM/ILD Necrotic myopathy |
SRP | Necrosis: Scattered Regeneration Immature fibers: Many |
Endomysium & Perimysium ↑ |
No | Signal Recognition Particle 54 (SRP54) |
Necrotic myopathy |
RIIM | Necrosis: Clustered in Borderzones |
Vein damage | No | Tif1γ NXP-2 |
DM/PM/ Paraneoplastic |
BCIM | Necrosis: Scattered Focal invasion |
Endomysium C5b-9 deposition |
B-lymphocyte foci/ EGC (ELS) |
ANA; PM-Scl100 | Polymyositis/ Other immune |
ICI | Necrosis: Clustered | Mitochondrial Δ Cardiac; Eye |
No | Striation | Necrotic myopathy |
Myopathies with Abundant Muscle Fiber Necrosis: Comparative Pathology |
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Myopathy Type |
Myopathy: Examples |
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Tissue Pathology: Other |
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Hereditary | |||||||||||
Sarcolemma Disorders |
Dystrophin Dysferlin |
Scattered Myopathic Groups |
Ongoing | Δ lesion, or Diffuse |
Endomysium Increased |
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Rhabdomyolysis Metabolic & Membrane Disorders |
Phosphorylase Malignant Hyperthermia Membrane disorders |
Scattered | Monophasic ± Ongoing |
Diffuse | No | ||||||
Toxic | |||||||||||
Rhabdomyolysis | Statin toxicity, acute Ethanol |
Scattered | Monophasic | Δ lesion, or Diffuse, Pale |
No | ||||||
Immune | |||||||||||
IMPP | Jo-1 & Synthetase Ab Multisystem Δ Dermatomyopathy |
Perifascicular Predominant |
Ongoing | Diffuse | Perimysium Damage | ||||||
HMGCR antibody |
Myopathies: Subacute or Chronic |
Scattered & Perifascicular |
Ongoing | Diffuse | Perimysium Damage | ||||||
SRP antibody | SRP Myopathy, Progressive, Severe |
Scattered | Ongoing | Diffuse | Endomysial Proliferation Perimysium Damage |
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LHIM | Myopathy, Subacute | Scattered | Ongoing | Peripheral | Histiocytes: Surround Myofibers |
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NXP-2 & Tif1γ antibodies |
RIIM Dermatomyopathy Paraneoplastic: ↑ Age |
Clustered: Vessel Borderzone areas |
Ongoing | Diffuse | Vessel: Veins & Capillaries Connective tissue |
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Mi-2 antibody | Dermatomyopathy | Scattered & Perifascicular |
Ongoing | Diffuse | |||||||
Focal | |||||||||||
Toxic | Injections Venoms |
Clustered | Monophasic | Diffuse, or Δ lesion |
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Ischemia | Vascular Disease | Clustered | Monophasic | Diffuse | Endomysium: Edema | ||||||
Freeze | Clustered | Monophasic Slow recovery |
Diffuse | Satellite cells Number reduced |
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![]() H & E Stain |
← Normal muscle fiber |
← Necrotic muscle fiber: Pale; Little phagocytosis | |
← Necrotic muscle fiber: Phagocytosis by macrophages | |
← Hypercontracted necrotic muscle fiber | |
← Perimysium |
![]() H & E Stain |
![]() H&E stain |
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Necrotic muscle fibers: Pale; Little phagocytosis (Arrows) | |
![]() Gomori trichrome stain |
![]() H&E Necrotic muscle fiber, Early
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![]() Gomori trichrome stain |
![]() Necrotic muscle fibers: Internal architecture has lost NADH staining (Arrow) ![]() NADH stain |
![]() Sudan black stain |
![]() H&E stain |
Membrane damage at several regions of individual fibers: Associated with clear regions in cytoplasm ![]() H&E stain |
![]() H&E stain |
![]() H&E stain |
![]() NADH stain |
![]() NADH stain |
![]() Congo red stain |
![]() H&E stain |
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Necrotic muscle fibers: Phagocytosis (Arrows) | |
![]() Gomori trichrome stain |
![]() H&E stain |
![]() NADH stain |
![]() Esterase stain |
![]() Acid phosphatase stain Necrosis: Varied Stages Early: Pale stained muscle fibers Later: Muscle fibers progressively replaced by acid phosphatase + cells (Right) ![]() Acid phosphatasae stain |
![]() Esterase stain Necrotic muscle fiber, Late Muscle fiber is invaded and replaced by phagocytes. |
![]() Esterase stain |
![]() H&E stain |
![]() Acid phosphatasae stain |
![]() H&E stain |
![]() Acid phosphatase stain |
![]() MHC Class I stain Very late stage necrosis: MHC Class I Stains remaining cells phagocytsing collapsed muscle fibers Stains capillaries (Normal) No staining of most muscle fibers (Normal) |
![]() Alkaline phosphatase stain Necrosis: Alkaline phosphatase stains around the rim of muscle fibers |
![]() Toluidine blue stain Necrotic muscle fiber (Longitudinal section) Pale Invaded by cells |
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![]() Toluidine blue stain Necrotic muscle fiber (Cross-section) Pale Invaded by cells |
![]() Toluidine blue stain Necrotic muscle fiber Pale Invaded by cells |
![]() Toluidine blue stain Cells in necrotic fiber |
![]() Toluidine blue stain Non-necrotic, abnormal muscle fiber (Left): Dilated SR |
![]() ![]() Stain: C5b-9 components of complement (Membrane attack complex (MAC)) Necrosis: C5b-9 deposition diffusely within muscle fiber cytoplasm ![]() |
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Necrosis: Early stage Pale muscle fiber cytoplasm Lipid droplets Two other muscle fibers have large lipid droplets but are not pale & necrotic ![]() H&E stain |
![]() H&E stain |
![]() H&E stain |
![]() H&E stain |
![]() H&E stain |
![]() Gomori trichrome stain |
![]() H&E stain |
![]() H&E stain |
![]() H&E stain |
![]() H&E stain |
![]() H&E stain |
![]() C5b-9 stain |
![]() H&E stain |
![]() H&E stain |
![]() H&E stain |
![]() H&E stain |