Calf enlargement has many causes; it may reflect true hypertrophy (enlargement of muscle fibers) or, more commonly, pseudohypertrophy, due to infiltration with tissue elements other than muscle.
Hypertrophy may be due to neuromuscular disorders producing:
- Chronic partial denervation, for example:
- peripheral neuropathy
- spinal muscular atrophy
- following paralytic poliomyelitis.
- Continuous muscle activity, for example:
- myotonia congenita
- Isaacs syndrome (neuromyotonia)
- generalized myokymia.
Pseudohypertrophy may be due to:
- Dystrophinopathies (Duchenne muscular dystrophy, Becker dystrophy), due to excess connective tissue.
- Infection/inflammation: myositis
- Infiltration: amyloidosis, tumor, cysticercosis
Coles A, Dick D. Unilateral calf hypertrophy. Journal of Neurology,Neurosurgery and Psychiatry 2004; 75: 1606
Wilson H, Kidd D, Howard RS, Williams AJ, Spencer GT. Calf hypertrophy following paralytic poliomyelitis. Postgraduate Medical Journal2000; 76: 179-181