Pseudohypertrophy of a muscle is characteristic of which disease?

• A. Duchenne muscular dystrophy
• B. Becker muscular dystrophy
• C. Polymyositis
• D. ALS

Answer: (A)

Pseudohypertrophy happens when muscle tissue is replaced by fat and fibrous tissue, so the muscle looks enlarged but is actually weaker. This pattern is classic in Duchenne muscular dystrophy, where loss of dystrophin leads to repeated muscle injury, degeneration, and replacement of muscle fibers with fat and connective tissue. The result is prominent enlargement of muscles like the calves while overall strength declines, especially with early onset proximal weakness. Becker muscular dystrophy can show similar changes but typically later and milder, so pseudohypertrophy is less characteristic. Polymyositis is an inflammatory process with muscle weakness and inflammatory cells, not fatty replacement causing enlargement. ALS causes neurogenic atrophy with muscle wasting, not pseudohypertrophy.