What is the appropriate evaluation to diagnose an aspergilloma?

Diagnostic Evaluation for Aspergilloma

The diagnosis of aspergilloma is established through the combination of characteristic chest imaging showing a fungal ball within a cavity and positive Aspergillus serology, typically without requiring invasive biopsy. 1

Essential Diagnostic Components

Radiographic Evaluation

Obtain a thin-section chest CT scan (MDCT, MSCT, or high-resolution CT) as the primary imaging modality, which is superior to plain radiography for diagnosis. 1 The characteristic CT findings include:

• A solid rounded mass of soft-tissue density within a spherical or ovoid cavity, separated from the cavity wall by an airspace of variable size and shape (the classic "air crescent sign" or "meniscus sign") 1, 2
• Thickened cavity wall with peripheral pleural thickening 1
• The fungal ball may be mobile (demonstrated by prone and supine positioning) or fixed with a spongework appearance containing air spaces 3
• Use 3-mm narrow sections with bone algorithm and wide window settings for optimal visualization 3

Important caveat: The air crescent sign is not 100% specific—it can be mimicked by intracavitary clot, hydatid cyst, Rasmussen aneurysm, pulmonary gangrene, or intracavitary malignancy. 2

Serological Testing

Measure serum Aspergillus IgG antibody (precipitins), which has >95% sensitivity for aspergilloma and serves as the most sensitive microbiological test. 1 Key points:

• Virtually all patients with aspergilloma have positive serum precipitating antibodies to Aspergillus antigens 1, 4
• A diagnostic cut-off of 27 mgA/L shows 95.6% sensitivity and 100% specificity 5
• Patients receiving corticosteroids may be seronegative despite active disease 1
• Rising IgG titers indicate disease progression or therapeutic failure 6, 7

Microbiological Evaluation

Obtain sputum culture for Aspergillus species, though this is neither sensitive nor specific:

• Positive sputum cultures occur in >50% of patients but do not confirm the diagnosis alone 4
• Sputum Aspergillus PCR testing is more sensitive than culture 1
• Aspergillus antigen testing is usually negative in aspergilloma (unlike invasive disease) 8

Clinical Assessment

Document the following clinical features to complete the diagnostic picture:

• Presence and severity of hemoptysis (the most common symptom, occurring in the majority of patients and potentially life-threatening) 1, 4
• Duration of symptoms ≥3 months to distinguish from acute processes 1
• Underlying lung disease such as prior tuberculosis, sarcoidosis, bullous emphysema, bronchiectasis, or fibrotic lung disease 1, 8
• Degree of immunocompromise (aspergilloma typically occurs in non-immunocompromised or minimally immunocompromised patients) 1, 5

When Biopsy Is NOT Required

Lung biopsy is usually not necessary when characteristic radiographic features are present with positive Aspergillus serology. 1 The diagnosis can be made clinically in the appropriate context.

When Additional Evaluation Is Needed

Consider bronchoscopy with bronchoalveolar lavage (BAL) or CT-guided biopsy only when:

• The diagnosis remains uncertain despite imaging and serology 1
• There is concern for alternative diagnoses (malignancy, other infections) 2
• Tissue invasion is suspected (suggesting chronic necrotizing pulmonary aspergillosis rather than simple aspergilloma) 1

Exclusion of Alternative Diagnoses

Actively exclude other causes of cavitary lung disease, particularly:

• Active or treated tuberculosis (obtain sputum AFB smears and cultures) 6, 5
• Lung malignancy (especially in patients with risk factors) 2
• Other fungal infections (histoplasmosis, coccidioidomycosis) 1

Common Diagnostic Pitfalls to Avoid

• Do not rely on sputum culture alone—it lacks both sensitivity and specificity for aspergilloma 4
• Do not assume negative Aspergillus serology excludes the diagnosis in patients on corticosteroids 1
• Do not confuse simple aspergilloma with chronic cavitary pulmonary aspergillosis (CCPA)—CCPA involves multiple cavities, progressive symptoms, and systemic inflammation over ≥3 months 1
• Do not overlook the air crescent sign mimics—always consider alternative diagnoses when clinical context doesn't fit 2