The image shows pseudohypertrophy of the muscles of the calves in a patient with Duchene Muscular Dystrophy. This X- linked recessive disease is caused by defective dystrophin- a protein that links myofiber cytoskeleton to the extracellular matrix. Its deficiency weakens the muscle membrane and promotes muscle degeneration.
This false enlargement results from fibro-fatty tissue accumulation in place of the muscle tissue. Legs progressively weaken and children are often wheelchair bound when they reach their tenth birthday.
Image via: https://obgynkey.com/myopathies/