Allergic Bronchopulmonary Aspergillosis (ABPA) is a complex pulmonary disorder resulting from a hypersensitivity reaction to the fungus Aspergillus fumigatus, primarily affecting patients with asthma or cystic fibrosis. Misdiagnosis or delayed recognition of ABPA can lead to progressive bronchiectasis, fibrosis, and ultimately, respiratory failure.
To aid clinicians and students in accurately diagnosing ABPA, the Rosenberg-Patterson Criteria provide a structured framework. These criteria are best remembered using the powerful mnemonic: “EPIC ARTS”—which includes all the major features of ABPA diagnosis.
This article elaborates on each diagnostic criterion, clinical relevance, and the underlying immunopathology in a structured, reader-friendly format.
Overview of ABPA
ABPA is an immunological disorder marked by:
- Type I hypersensitivity (IgE-mediated)
- Type III hypersensitivity (immune complex-mediated)
- Predominantly seen in atopic individuals with asthma or cystic fibrosis
The result is a chronic inflammatory response within the bronchial tree, leading to mucus plugging, airway remodeling, and recurrent infections.
Mnemonic: EPIC ARTS – Rosenberg-Patterson Diagnostic Criteria
The mnemonic EPIC ARTS captures all essential diagnostic features:
| Letter | Diagnostic Feature |
|---|---|
| E | Eosinophilia |
| P | Precipitating antibodies |
| I | IgE elevated in serum |
| C | Central bronchiectasis |
| A | Asthma |
| R | Radiographic fleeting pulmonary opacities |
| T | Test for skin aspergillosis (positive Type I hypersensitivity) |
| S | Serum A. fumigatus-specific IgG & IgE |
Let’s explore each component in detail.
E – Eosinophilia
Peripheral eosinophilia is a hallmark of allergic conditions and is prominent in ABPA.
- Eosinophil count >500/mm³
- Reflects the Th2-skewed immune response
- Usually seen during exacerbations
Note: May be suppressed in corticosteroid-treated patients.
P – Precipitating Antibodies
Detection of precipitating IgG antibodies against Aspergillus fumigatus indicates ongoing immune complex formation.
- Identified by double immunodiffusion or electrosyneresis
- Part of the Type III hypersensitivity mechanism
- Presence supports the diagnosis even in the absence of overt infection
I – IgE Elevated in Serum
A cornerstone of ABPA diagnosis is elevated total serum IgE, typically:
- >1000 IU/mL (or >417 IU/mL in less stringent criteria)
- Marker of atopy and fungal sensitization
Serial monitoring of IgE is essential for assessing treatment response and relapse.
C – Central Bronchiectasis
Bronchiectasis is irreversible dilatation of the bronchi due to chronic inflammation and destruction of the bronchial wall.
In ABPA:
- Central bronchiectasis (affecting proximal bronchi) is pathognomonic
- Detected via high-resolution CT (HRCT) chest
Features:
- “Finger-in-glove” appearance from mucus plugging
- Ring shadows and tram-track lines on imaging
A – Asthma
Asthma is almost universally present in patients with ABPA, typically with:
- Severe or uncontrolled asthma
- Recurrent wheezing, coughing
- Poor response to conventional bronchodilators alone
Important: Not all asthmatics have ABPA, but ABPA should be suspected in asthmatics with frequent exacerbations and poor steroid response.
R – Radiographic Fleeting Pulmonary Opacities
Chest imaging reveals transient, migratory infiltrates, especially during acute episodes.
Seen as:
- Pulmonary opacities that shift from one region to another
- May mimic pneumonia but fail to resolve with antibiotics
- Caused by mucus impaction and inflammation
T – Test for Skin Aspergillosis (Type I Hypersensitivity)
The skin prick test for A. fumigatus antigens is often:
- Strongly positive within minutes
- Denotes Type I (immediate) hypersensitivity
This is a diagnostic hallmark, especially in distinguishing ABPA from other pulmonary fungal infections.
S – Serum Aspergillus fumigatus-Specific IgG & IgE
Serologic testing confirms:
- Presence of IgG (chronic exposure)
- Elevated specific IgE (acute hypersensitivity)
Both tests improve diagnostic precision and differentiate ABPA from:
- Invasive aspergillosis
- Simple colonization
- Aspergilloma
Summary Table: EPIC ARTS Mnemonic
| Mnemonic | Feature | Diagnostic Role |
|---|---|---|
| E | Eosinophilia | Indicates allergic inflammation |
| P | Precipitating antibodies | Type III hypersensitivity |
| I | Elevated total IgE | Monitoring and diagnosis |
| C | Central bronchiectasis | Seen on HRCT; hallmark finding |
| A | Asthma | Strongly associated comorbidity |
| R | Radiographic opacities | Transient/migratory, non-infectious |
| T | Positive skin prick test | Type I hypersensitivity |
| S | Serum Aspergillus-specific IgG/IgE | Serological confirmation |
Revised ISHAM Criteria (2020): A Modern Perspective
Though Rosenberg-Patterson criteria remain classic, the International Society for Human and Animal Mycology (ISHAM) proposes:
Essential Criteria:
- Asthma or cystic fibrosis
- Sensitization to Aspergillus fumigatus
- Elevated total serum IgE (>1000 IU/mL)
Other Criteria (at least 2 required):
- Eosinophilia
- Radiographic opacities
- Positive serum specific IgG/IgE
- Central bronchiectasis
Clinical Stages of ABPA
ABPA progresses through distinct clinical stages:
| Stage | Description |
|---|---|
| I | Acute stage – classic symptoms, radiographic findings |
| II | Remission – asymptomatic, normal IgE |
| III | Exacerbation – rising IgE, worsening symptoms |
| IV | Corticosteroid-dependent asthma |
| V | Fibrotic stage – irreversible damage, end-stage lung disease |
Symptoms of ABPA
- Persistent productive cough with brownish plugs
- Wheezing, dyspnea
- Recurrent chest infections
- Hemoptysis (occasionally)
- Weight loss, fatigue, malaise
Symptoms often overlap with severe asthma and bronchiectasis—prompting misdiagnosis.
Investigations Summary
| Test | Role |
|---|---|
| CBC | Eosinophilia |
| Total IgE | Diagnostic and prognostic |
| Skin Prick Test | Immediate hypersensitivity |
| HRCT Chest | Central bronchiectasis, mucus plugging |
| Serum Specific IgE/IgG | Aspergillus sensitization |
| Sputum Culture | May grow A. fumigatus, but not diagnostic |
Treatment Approach
1. Corticosteroids (Mainstay)
- Prednisolone 0.5 mg/kg/day for 2–4 weeks
- Taper over 3–6 months
- Controls inflammation and prevents exacerbations
2. Antifungal Therapy (Adjunctive)
- Itraconazole (200 mg BID for 16 weeks)
- Reduces fungal burden and steroid dependence
3. Bronchodilators
- For asthma symptom control (e.g., salbutamol)
4. Biologic Agents
- Omalizumab (anti-IgE) – considered in refractory ABPA with high IgE
- Mepolizumab – anti-IL-5 for eosinophilic phenotypes
Prognosis
Early diagnosis and treatment = better outcomes
Delayed or missed ABPA can cause:
- Progressive bronchiectasis
- Fibrotic lung disease
- Chronic respiratory failure
Regular monitoring of IgE levels and pulmonary function tests is critical.
Differentiating ABPA from Other Conditions
| Condition | Key Difference |
|---|---|
| Asthma | No eosinophilia or fungal sensitization |
| Bronchiectasis | Usually non-central and non-allergic |
| Invasive Aspergillosis | Immunocompromised host, systemic symptoms |
| Aspergilloma | Fungal ball in cavity, not hypersensitivity-related |
Frequently Asked Questions (FAQs)
Q1: Is ABPA contagious?
A: No. ABPA is a non-infectious hypersensitivity reaction, not a transmissible fungal infection.
Q2: Can ABPA occur without asthma?
A: Rarely. ABPA almost always occurs in patients with asthma or cystic fibrosis.
Q3: Why is IgE monitoring important in ABPA?
A: Total serum IgE helps:
- Confirm diagnosis
- Monitor treatment response
- Detect relapses early
Q4: Can ABPA recur?
A: Yes. Relapses are common. Hence, regular follow-up and long-term corticosteroid planning are needed.
Q5: What is the role of antifungals in ABPA?
A: They reduce fungal burden, which lowers antigenic stimulus and helps taper steroids.
