Which is the most common organ involved in sarcoidosis?
**Core Concept**
Sarcoidosis is a systemic granulomatous disease characterized by the formation of non-caseating granulomas in various organs, leading to inflammation and potentially causing organ dysfunction. The disease can affect multiple organs, but some are more commonly involved than others.
**Why the Correct Answer is Right**
The lungs are the most common site of involvement in sarcoidosis, with up to 90% of patients experiencing pulmonary symptoms. This is due to the high concentration of lymphoid cells and macrophages in the lung interstitium, which are the primary cells involved in the formation of granulomas. The accumulation of these cells leads to inflammation and the formation of non-caseating granulomas, which are a hallmark of the disease. The lungs are also the primary site of disease manifestation in many patients, making it the most common organ involved in sarcoidosis.
**Why Each Wrong Option is Incorrect**
**Option A:** The skin is a common site of involvement in sarcoidosis, but it is not the most common organ involved. While skin lesions can be a significant manifestation of the disease, they are not as common as pulmonary symptoms.
**Option B:** The liver is a less common site of involvement in sarcoidosis, although it can be affected in some cases. Liver involvement is often asymptomatic and may not be detected until later in the disease course.
**Option C:** The heart is rarely involved in sarcoidosis, although cardiac involvement can occur in some cases. Cardiac sarcoidosis is a serious complication of the disease, but it is not the most common organ involved.
**Clinical Pearl / High-Yield Fact**
The presence of bilateral hilar lymphadenopathy (BHL) on chest radiograph is a classic finding in sarcoidosis, particularly in the early stages of the disease. BHL is often seen in patients with pulmonary sarcoidosis and can be a useful diagnostic clue.
**Correct Answer:** C.