“Loeffler’s syndrome” is characterized by:
**Core Concept**
Loeffler's syndrome is a type of hypersensitivity pneumonitis, characterized by an allergic reaction to inhaled antigens, leading to inflammation and granulomatous changes in the lungs.
**Why the Correct Answer is Right**
The condition is caused by the deposition of eosinophils and Charcot-Leyden crystals in the lung tissue, resulting from a type I hypersensitivity reaction. This reaction is mediated by IgE antibodies, which bind to mast cells and basophils, triggering the release of histamine and other chemical mediators. The eosinophils then infiltrate the lung tissue, causing inflammation and granulomatous changes.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because Loeffler's syndrome is not primarily characterized by an increase in neutrophils, which are more commonly associated with acute bacterial infections.
**Option B:** This option is incorrect because Loeffler's syndrome is not a type of chronic obstructive pulmonary disease (COPD), which is a progressive lung disease characterized by airflow limitation.
**Option C:** This option is incorrect because Loeffler's syndrome is not a type of lung cancer, which is characterized by the uncontrolled growth of abnormal cells in the lung tissue.
**Clinical Pearl / High-Yield Fact**
Loeffler's syndrome is often associated with exposure to organic dusts, such as bird droppings or mold, and can be diagnosed based on a combination of clinical symptoms, radiographic findings, and laboratory tests.
**Correct Answer: D. Eosinophilic pneumonia.**