Diagnostic features of allergic broncho-pulmonary aspergillosis (ABPA) include all of the following, EXCEPT:
**Core Concept**
Allergic broncho-pulmonary aspergillosis (ABPA) is a hypersensitivity reaction to Aspergillus fumigatus, leading to lung inflammation and airway obstruction. It is characterized by a complex interplay between genetic predisposition, environmental exposure, and immune system dysregulation.
**Why the Correct Answer is Right**
ABPA is marked by the presence of elevated serum IgE levels, positive skin prick test to Aspergillus, and central bronchiectasis on high-resolution computed tomography (HRCT) scans. The condition often co-exists with asthma, and patients may exhibit a marked response to corticosteroid therapy. The pathogenesis of ABPA involves an exaggerated Th2 response, leading to eosinophilia, mucus production, and airway remodeling.
**Why Each Wrong Option is Incorrect**
**Option A:** Elevated serum IgE levels are actually a diagnostic feature of ABPA, making this option incorrect.
**Option B:** Positive skin prick test to Aspergillus is also a hallmark of ABPA, so this option is incorrect as well.
**Option C:** Central bronchiectasis on HRCT scans is a characteristic finding in ABPA, thus this option is incorrect.
**Clinical Pearl / High-Yield Fact**
Remember the "5 As" of ABPA: Asthma, Allergic rhinitis, Aspergillus sensitization, Airway obstruction, and Bronchiectasis. These features often co-occur in patients with ABPA.
**Correct Answer:** D.