Neurogenic muscle hypertrophy in type III spinal muscular atrophy.

Neurogenic muscle hypertrophy is very unusual and has been rarely described. We described a 25-year-old woman presented with proximal muscle weakness with calf muscle hypertrophy. Limb magnetic resonance imaging scans showed increased muscle bulk without fatty changes, and a muscle biopsy revealed prominent hypertrophic type II muscle fibers. A mutation in SMN1 was found in a genetic analysis. This is the first report of neurogenic muscle hypertrophy seen in genetically confirmed spinal muscular atrophy III.