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MFM3 (LGMD 1A): Myotilin mutations

Aggregates Myopathy, Chronic Spheroid bodies Type 1 predominance Vacuoles

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Myopathy, Chronic

H & E stain

Chronic myopthy
  Perimysial connective tissue: Replaced by fat
  Muscle fibers
    Varied size
    Some with vacuoles or aggregates

Sudan black stain

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Sarcolemma: Irregular

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Clustered Regeneration
Several new regenerated muscle fibers in region previously occupied by one hypertrophied muscle fiber

H&E stain

H&E stain

H&E stain

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Partial Fusion: Muscle fibers

Gomori trichrome stain

NADH stain

H&E stain

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VvG stain

Large, Partially-fused or Branched Muscle fibers ¹
  Contain internal nuclei
Branched Muscle Fiber (Top right): Fused at lower 2 images; Unfused (2 smaller fibers) at top

Gomori trichrome stain

NADH stain

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Internal Nuclei
Many nuclei inside individual muscle fibers

H&E stain

H&E stain

Congo red stain

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Spheroid Bodies

H & E stain

LGMD 1A: Spheroid bodies

Gomori trichrome stain

NADH stain

Myotilin stain

SMI-31 stain

SMI-31 stain

LC3 stain

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Spheroid bodies: Ultrastructure

From: R Schmidt

Spheroid bodies: Ultrastructure
Spheroid bodies: Ultrastructure, Fibrillar components

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LGMD 1A: Aggregates

Gomori Trichrome stain

Gomori Trichrome stain

Gomori Trichrome stain

Muscle fiber pathology   Varied fiber size   Vacuoles   Inclusions     Hyaline & Cytoplasmic body-like material

GT stain; From: Drs Montse Olivé & Isidro Ferrer

NADH stain

VvG stain

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Internal architecture: Varied patterns

NADH stain

NADH stain

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AGGREGATES

Myotilin stain

Myotilin aggregates in muscle fibers

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VCP stain

VCP aggregates in muscle fibers

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Desmin stain

Desmin aggregates in muscle fibers

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Cytoplasmic Aggregates & Vacuoles with Sarcolemmal Features

Dystrophin stain Dystrophin: Abnormal collections in muscle fiber cytoplasm

Dys2 stain

Dys 7G1 (Rod domain, Exon 46) stain

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δ-Sarcoglycan stain

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Caveolin-3 stain

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LAMP2 stain

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Dysferlin stain

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Lipopigment: Subsarcolemmal

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Aggregates: May contain Glycogen

PAS stain

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MFM3 (LGMD 1A): Vacuoles

H & E stain

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H & E stain; From: Drs Montse Olivé & Isidro Ferrer Muscle fiber pathology   Varied fiber size   Abnormal internal architecture     Hyaline inclusions     Basophilic punctate material   Vacuoles

H & E stain

H & E stain

Gomori Trichrome stain

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MFM3 (LGMD 1A)
  Type 1 muscle fiber predominance

ATPase pH 4.3 stain

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MFM3 (LGMD 1A): Disorganized Sarcomeres

From: R Schmidt

Z-line Pathology
  Rod-like structures ± associated filaments (Above)
  Streamed Z-band-like material without associated filaments or sarcomeres

From: R Schmidt

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Return to Neuromuscular
Return to LGMD 1A

1. Int J Mol Sci 2026;27:684

9/9/2026