“Chain of lakes” appearance on X-ray is seen in:
**Core Concept**
The "chain of lakes" appearance on X-ray refers to a radiographic pattern seen in the lungs, characterized by multiple rounded opacities that are connected by thin linear structures, resembling a chain of lakes. This pattern is typically associated with pulmonary edema or alveolar filling.
**Why the Correct Answer is Right**
The "chain of lakes" appearance is often seen in pulmonary edema due to congestive heart failure, where fluid accumulates in the alveoli and interstitial spaces, causing the air-filled alveoli to be compressed and appear as rounded opacities. The thin linear structures connecting these opacities represent the residual air-filled alveoli. This pattern is also seen in conditions that cause alveolar filling, such as acute respiratory distress syndrome (ARDS).
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the "chain of lakes" appearance is not typically associated with pulmonary embolism, which may show a "wedge-shaped" or "geographic" pattern on X-ray.
**Option B:** This option is incorrect because the "chain of lakes" appearance is not characteristic of pneumonia, which may show a patchy or lobar infiltrate on X-ray.
**Option C:** This option is incorrect because the "chain of lakes" appearance is not typically associated with atelectasis, which may show a "cut-off" or "collapsed" lung pattern on X-ray.
**Clinical Pearl / High-Yield Fact**
The "chain of lakes" appearance is a classic radiographic pattern of pulmonary edema and should be considered in patients with symptoms of heart failure or acute respiratory distress.
**Correct Answer: C. Pulmonary edema**