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MULTICORE MYOPATHY: Pathology

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Histology

• Multiple small areas with reduced oxidative enzyme staining
• Absent: Mitochondria
• Present in both type 1 & 2 fibers
• Length: Shorter than cores

Ultrastructure

• Myofibrils: Focal disruption of few sarcomeres

Disease associations

• Hereditary
• Denervation
• Tenotomy
• Rule out: Motheaten

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NADH stain
NADH stain

Multicores
  Mutliple internal clear zones in muscle fibers

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Myopathic changes in multicore disease

• Fiber size: Variability
• Internal nuclei: Many fibers

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NADH stain

Minicore-like lesions in muscle with denervation changes: Adult

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Multicore/Minicore: Titin mutations

Patient: 2 year old female with noncompaction cardiomyopathy, hypotonia & developmental delay
Genetics: Titin mutations K2186C & D19486Y

From Chunyu (Hunter) Cai

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H&E stain

Myopathic features
  Fiber sizes: Abnormal variation
  Internal nuclei

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NADH stain

Minicores

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ATPase pH 9.4 stain

Fiber types
  Type 1 fibers: Predominance; Smallness

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Muscle Multi/Minicores: Ultrastructure
  Horizontal Z band streaming: Multifocal regions

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Return to Multicore myopathy
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10/23/2023