MD pathology includes replacement of muscle with fat and connective tissue. What is this process called?

• A. Hypertrophy
• B. Atrophy
• C. Fatty infiltration with connective tissue replacement
• D. Dysplasia

Answer: (C)

The pattern at play is that muscle fibers are progressively lost and the space they occupy is filled by non-contractile tissue. This specific change is called fibrofatty replacement of muscle, meaning fatty infiltration with connective tissue replacement. As dystrophic fibers degenerate, fat cells and fibrous tissue take their place, weakening the muscle overall. Hypertrophy would involve larger muscle fibers, not replacement by fat and fibrous tissue. Atrophy describes shrinking from fiber loss but not the characteristic fibrofatty replacement. Dysplasia is abnormal development of tissue. So the described process aligns with fibrofatty replacement.