Allergic bronchopulmonary aspergillosis is (ABPA) usually diagnosed by A/E:
**Core Concept**
Allergic bronchopulmonary aspergillosis (ABPA) is a hypersensitivity reaction to Aspergillus fumigatus, characterized by asthma-like symptoms, eosinophilia, and pulmonary infiltrates. It typically occurs in individuals with pre-existing asthma or cystic fibrosis.
**Why the Correct Answer is Right**
The diagnosis of ABPA is primarily based on clinical and radiological findings, along with laboratory tests that demonstrate an immune response to Aspergillus fumigatus. This includes elevated serum IgE levels, positive skin prick test or radioallergosorbent test (RAST) for Aspergillus, and computed tomography (CT) scans showing central bronchiectasis and fleeting pulmonary infiltrates.
**Why Each Wrong Option is Incorrect**
**Option A:** Elevated IgG antibodies against Aspergillus are not specific for ABPA and can be seen in other conditions, such as chronic aspergillosis.
**Option B:** A positive Aspergillus culture from sputum or bronchoalveolar lavage (BAL) fluid is not diagnostic for ABPA, as it can be present in healthy individuals or those with other types of aspergillosis.
**Option C:** A normal serum IgE level does not exclude ABPA, as some patients may have normal or low IgE levels despite a positive immune response to Aspergillus.
**Clinical Pearl / High-Yield Fact**
In ABPA, the presence of central bronchiectasis on CT scans is a key diagnostic criterion, as it indicates long-standing airway damage and inflammation.
**Correct Answer: D. Elevated serum IgE levels alone are not sufficient for diagnosis.**