Starry sky appearance is seen in-
**Core Concept**
The "starry sky" appearance is a characteristic radiological finding seen in certain conditions, resulting from the presence of multiple small calcifications that resemble stars against a dark background. This phenomenon is often observed in imaging studies, particularly in chest X-rays or CT scans.
**Why the Correct Answer is Right**
The "starry sky" appearance is typically seen in silicosis, a lung disease caused by the inhalation of silica particles. The calcifications in silicosis are thought to result from the body's attempt to contain and eliminate the silica particles, leading to the formation of calcified granulomas that create the characteristic "starry sky" pattern. This pattern is a result of the calcifications being distributed throughout the lung fields, creating a mottled appearance that resembles a starry night sky.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because the "starry sky" appearance is not typically associated with tuberculosis (TB), although TB can cause calcifications in the lungs. TB calcifications tend to be more localized and may not create the same diffuse, mottled appearance as silicosis.
* **Option B:** This option is incorrect because the "starry sky" appearance is not characteristic of asbestosis, a lung disease caused by the inhalation of asbestos fibers. Asbestosis typically causes a more diffuse, fibrotic pattern in the lungs rather than the calcified granulomas seen in silicosis.
* **Option C:** This option is incorrect because the "starry sky" appearance is not typically associated with sarcoidosis, a systemic disease characterized by the formation of non-caseating granulomas. While sarcoidosis can cause calcifications in the lungs, the pattern is often more focal and may not create the same diffuse, mottled appearance as silicosis.
**Clinical Pearl / High-Yield Fact**
The "starry sky" appearance in silicosis is an important radiological finding that can help diagnose this occupational lung disease. It is essential to consider the patient's occupational history and exposure to silica dust when interpreting imaging studies.
**Correct Answer:** C.