Table 2. Histopathological Findings.
Variable | 20-1 | 20-2 | 20-3 | 20-4 |
---|---|---|---|---|
Overall interpretation | Nemaline myopathy | Neurogenic atrophy With myopathic features | Nemaline myopathy with neurogenic atrophy | Nonspecific congenital myopathy |
Fiber type predominance | Type I | Type II | Type II | No predominance |
Fiber size variation | + | + | + | + |
Nemaline rods | +, Occasional | − | + (1%-5% Fibers)- | − |
Lipid accumulation | NA | + | + | + |
Endomysial connective tissue | ↑ | ↑ | ↑ | ↑ |
Myofiber degeneration/regeneration | + | − | − | + |
Additional findings | Ring and atrophic fibers, internalized nuclei present | First muscle biopsy (in infancy) consistent with neurogenic atrophy; second (at age 11 y) showed grouped atrophy, round and angulated fibers, increased internalized nuclei | Grouped atrophy, angulated and atrophic fibers, nuclear chains | NA |
Electron microscopy findings | Few nemaline rods, focal myofibrillar disruption, Z-band smearing | NA | Nemaline rods seen in continuity with Z-bands often associated with disruption of myofibrillar apparatus | NA |
Abbreviations: NA, not available; +, present; −, absent; ↑, increasing.