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MYOTONIC DYSTROPHY

DM1 DM2

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Myotonic Dystrophy 1 (DM1)

Chronic Late Mild

Rossolimo "De la myotonie atrophique" 1902

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DM1: Adult, Chronic changes

Muscle fibers   Size: Variation   Myonuclei     Numbers: Increased     Shapes: Irregular     Internal       Present in many muscle fibers       Several in individual fibers       Often clumped & in longitudinal chains     Pyknotic clumps   Acid phosphatase + granules   Replacement by Fat H&E stain

Perimysium: Connective tissue replaced by fat H&E stain

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Congo red stain

Congo red stain

H&E stain

Internal nuclei: Many; Irregular shapes; Often in longitudinal chains H&E stain

H&E stain

Gomori trichrome stain Internal nuclei   Nuclei may be mildly large & clustered

Rossolimo "De la myotonie atrophique" 1902

Gomori trichrome stain

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Internal architecture of muscle fibers: Disordered   Aggregates   Clear regions NADH stain

NADH stain

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Aggregates in muscle fiber cytoplasm AMPDA stain

Fiber type abnormality: All fibers are type 1 ATPase pH 9.4 stain

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Acid phosphatase positive granules in muscle fibers
Acid phosphatase stain	Acid phosphatase stain

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H&E stain

DM1: Vacuoles

Gomori trichrome stain

VvG stain

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H&E stain

Pyknotic nuclear clumps: May be large

Congo red stain

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Myotonic dystrophy (DM1): Mild & Earlier changes

H&E stain

Internal nuclei
Pyknotic nuclear clumps

H&E stain

H&E stain

H&E stain Fiber sizes: Internal nuclei: In some fibers

NADH stain Type I (darker) fibers: Smaller Internal architecture: Disordered

NADH stain

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Internal nuclei: In type 1 & 2 muscle fibers

ATPase pH 9.4 stain

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Emerin stain

DM1: Myonuclei
  Increased numbers around periphery of muscle fibers
  Irregular shapes (Below)

Emerin stain

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Myotonic dystrophy (DM1): Late changes

H&E stain Muscle fibers   Size: Atrophy & Some hypertrophy   Pyknotic nuclear clumps   Nuclei: Large & Irregular shapes Endomysial connective tissue: Moderately increased

Congo red stain

VvG stain

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H&E stain

Pyknotic nuclear clumps
  Large
  May be present in connective tissue with few intact muscle fibers

H&E stain

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Myotonic dystrophy, Type 2 (DM2)

Pathology
  Nuclei: Internal; More in type 2 fibers
  Pyknotic nuclear clumps
  Replacement of muscle by fat

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H & E stain

Internal nuclei: Multiple in individual fibers

H & E stain

H & E stain

Congo red stain

H & E stain Internal nuclei: Multiple in individual fibers

ATPase pH 9.4 Internal nuclei (clear regions) Most commonly in type 2 (dark) muscle fibers

ATPase pH 9.4

Internal nuclei (clear regions)
Most common in type 2 (dark) muscle fibers
Fiber Sizes
  Type 2 (Pale): Mildly smaller than Type I

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DM2: Fiber types

ATPase pH 4.6

DM2: 2B Fibers
  2B fibers (Intermediate stain): Abnormally varied colors

ATPase pH 4.6

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ATPase pH 4.3

DM2: Fiber types, ATPase pH 4.3
  Normal staining for 2 fiber types type 1 (Dark) & type 2 (Light)
  Type I fibers mildly larger than type 2
  Few or No type 2C fibers (Intermediate color)

ATPase pH 4.3

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LYSOSOMAL Structures Cytoplasmic granules:   Acid Phosphatase positive granules:     Scattered in cytoplasm Acid Phosphatase

Acid Phosphatase

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Pyknotic nuclear clumps

H & E stain

Pyknotic nuclear clumps: Large & small clusters of nuclei

H & E stain

Congo red stain

Pyknotic nuclear clumps: Large clusters of nuclei among larger muscle fibers

Congo red stain

H & E stain	NADH stain	Esterase
Pyknotic nuclear clumps: Dark-stained

NADH stain

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From: Cory Toth MD Pyknotic nuclear clump: Ultrastructure

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Myotonic dystrophy, Type 2 (DM2): Late

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Pyknotic nuclear clumps: Large
Muscle fibers: Largest are hypertrophied

Congo red stain

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Pyknotic nuclear clumps: Nuclei stained for emerin

Emerin stain

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Muscle fibers & Perimysium: Replaced by fat

Sudan Black stain

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6/2/2016