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Hypokalemic Periodic Paralysis

General Pathology: Early; During attacks of weakness Vacuoles Internal Sharp borders Contents: Clear or Amorphous debris Tubular aggregates Vacuoles: Evolution Non-vacuolated regions T-tubule system: Dilated & Proliferating Sarcoplasmic reticulum: Dilated; Contains amorphous material; Surrounded by glucogen Evolving vacuoles Appearance: Rarefaction Stain for NADH & Acid phosphatase Poorly demarcated Contain amorphous material & Multiple small vacuoles Intermediate vacuoles Well demarcated Contain amorphous matrix ± Calcified SR vesicles Mature vacuoles Limited by membrane: Stabilized by cytoskeletal proteins Contain fine granular material Remodeled vacuoles Mature vacuoles containing sarcoplasmic invaginations with glycogen granules Ruptured vacuoles: May produce muscle fiber necrosis

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Pathology: Early

NADH stain

NADH stain

Vacuoles: Variable shape & size; Sharp rim; Clear or filmy contents
Tubular aggregates: Stain for NADH

H & E stain

H & E stain

H & E stain

Gomori trichrome stain

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AMPDA: Stains tubular aggregates but not contents within vacuoles

AMPDA stain

AMPDA stain

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Pathology: Late; During permanent weakness

• Internal architecture changes
  • Vacuoles
  • Tubular aggregates
• Chronic myopathic changes
  • Muscle fibers
    • Size: Varied; Small & Large
    • Internal nuclei
    • Split fibers
  • Endomysial connective tissue: Increased

H & E stain

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Hypokalemic Periodic Paralysis: Large Tubular Aggregates

H & E stain

H & E stain

H & E stain

VvG stain

NADH stain

NADH stain

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Return to Hypokalemic periodic paralysis

6/22/2015