What does it mean if an abnormality is well-defined?

• A. Punched-out
• B. Corticated (uniform)
• C. Sclerotic (non-uniform)
• D. Internal radiolucent/hypodense rim

Answer: (B)

A well-defined radiographic abnormality is typically explained by a corticated margin—the presence of a thin, uniform radiopaque border that outlines the lesion. This cortex around the lesion shows that the bone has had time to react as the lesion grows, which is often seen with benign or slow-growing processes. That smooth, continuous border is what makes the lesion appear well circumscribed.

So the best description is corticated (uniform) because it captures that neat, uniform outer shell around the lesion. Other patterns don’t fit the same idea: a punched-out appearance emphasizes radiolucent cavities without a uniform outer cortex; a sclerotic border described as non-uniform suggests irregular, uneven thickening rather than a neat cortex; and an internal radiolucent rim implies a rim within the lesion itself rather than the characteristic outer corticated border.