Which pulmonary lesion is classically described as a round radiographic opacity resembling a coin?

• A. Adenocarcinoma
• B. Hamartoma
• C. Granuloma
• D. Cyst

Answer: (B)

A coin lesion on a chest radiograph is a solitary, round, well-defined pulmonary nodule. A hamartoma fits this description best because it typically appears as a small, smooth, round opacity and is the well-known benign cause of a coin-like nodule. Imaging often shows characteristic calcifications described as popcorn calcifications, which strongly point to a hamartoma.

Other lesions can be round nodules, but they lack these classic features. Adenocarcinoma and granuloma can present as solitary nodules, but they more often show irregular margins or different calcification patterns and growth behavior. A cyst is an air-filled cavity with a wall, not a dense solid round opacity.