Sarcoidosis is characterised by all except
**Core Concept**
Sarcoidosis is a systemic granulomatous disease characterized by the formation of non-caseating granulomas in various organs, including the lungs, lymph nodes, skin, and eyes. The exact pathogenesis is unclear, but it is believed to involve an abnormal immune response to an unknown antigen.
**Why the Correct Answer is Right**
The correct answer is related to the pathophysiology of sarcoidosis. Sarcoidosis is indeed characterized by the presence of non-caseating granulomas, which are aggregates of immune cells, including macrophages, lymphocytes, and giant cells, that attempt to wall off foreign substances. The disease is also associated with the activation of T helper 1 cells and the production of cytokines such as interferon-gamma. The formation of granulomas in sarcoidosis is a result of the body's attempt to contain the immune response and prevent tissue damage.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it does not accurately describe a characteristic of sarcoidosis. While sarcoidosis can affect the lungs, it is not the only organ involved, and the disease is not solely characterized by the presence of fibrosis.
* **Option B:** This option is incorrect because it does not accurately describe a characteristic of sarcoidosis. Sarcoidosis is not primarily characterized by the presence of caseating granulomas, which are typically seen in tuberculosis.
* **Option C:** This option is incorrect because it does not accurately describe a characteristic of sarcoidosis. While sarcoidosis can cause hypercalcemia, it is not the primary cause of this condition.
**Clinical Pearl / High-Yield Fact**
Sarcoidosis can affect any organ in the body, but the lungs, lymph nodes, skin, and eyes are the most commonly affected sites. The disease can be asymptomatic or can cause a wide range of symptoms, including cough, shortness of breath, fatigue, and skin lesions.
**Correct Answer:** None of the above.