True about Sarcoidosis is?
**Core Concept**
Sarcoidosis is a systemic granulomatous disease characterized by the formation of non-caseating granulomas in various organs, particularly the lungs and lymph nodes. The exact cause of sarcoidosis remains unknown, but it is believed to result from an abnormal immune response to an unknown antigen.
**Why the Correct Answer is Right**
The correct answer is related to the pathophysiology of sarcoidosis, which involves the formation of non-caseating granulomas. These granulomas are composed of activated macrophages and T-lymphocytes that accumulate in response to an unknown antigen. The immune response in sarcoidosis is characterized by an imbalance between Th1 and Th2 cytokines, leading to the production of granulomatous inflammation.
**Why Each Wrong Option is Incorrect**
**Option A:** Sarcoidosis is caused by a bacterial infection.
* This is incorrect because the exact cause of sarcoidosis remains unknown, and it is not believed to be caused by a bacterial infection.
**Option B:** Sarcoidosis is characterized by the presence of caseating granulomas.
* This is incorrect because sarcoidosis is characterized by non-caseating granulomas, not caseating granulomas.
**Option C:** Sarcoidosis primarily affects the skin and joints.
* This is incorrect because while sarcoidosis can affect the skin and joints, it primarily affects the lungs and lymph nodes.
**Clinical Pearl / High-Yield Fact**
Sarcoidosis can affect any organ system, and it is often associated with an increased risk of developing lymphoma and other autoimmune disorders.
**Correct Answer: B. Sarcoidosis is characterized by the presence of non-caseating granulomas.**