MYASTHENIA GRAVIS

Neuromuscular Junctions

Esterase stain

Small neuromuscular junctions from patients with congenital (left) and acquired (right) myasthenia.

Esterase stain

Normal neuromuscular junctions.

Lymphorrhages

H&E stain

H&E stain

Lymphorrhages from patients with myasthenia gravis and thymoma.

Myasthenia Gravis: Muscle pathology¹

• AChR Ab+
  • Muscle fiber atrophy: Type I & II
  • Pyknotic nuclear clumps: More without adequate treatment
  • Muscle fiber type grouping: Some patients
  • Internal architecture: Disordered; Minicores
• MuSK Ab+
  • COX- muscle fibers: Present in < 2% of fibers
  • Internal architecture: Disordered; Minicores

NEUROMUSCULAR JUNCTION ANATOMY: NORMAL & MYASTHENIA GRAVIS From Drachman