Aspergillus lung disease

Question 1

What is Aspergillus lung disease?

Answer 1

AKA Aspergillosis. Lung disease associated with Aspergillus fungal infection.

Question 2

What is the aetiology of Aspergillus lung disease?

Answer 2

Inhalation of the ubiquitous (found everywhere) Aspergillus (usually Aspergillus fumigantes) spores, that grows in organic matter in soil. Humans routinely inhale the aerosolised conidia. The conidia are promptly eliminated from the respiratory tract or may lead to colonisation or infection dependent on the underlying local and general immune status of the host.

Question 3

What are the risk factors for Aspergillosis? (x4)

Answer 3

History of transplant, immunosuppressed (AIDS and immunosuppression), haematological malignancy, pre-existing lung cavity (TB, abscess, infarct, sarcoidosis, bronchiectasis).

Question 4

What are four different clinical pictures of Aspergillus lung disease?

Answer 4

Aspergilloma, allergic bronchopulmonary aspergillosis (ABPA), chronic necrotising aspergillosis, and invasive aspergillosis.

Question 5

What is the pathophysiology of aspergilloma?

Answer 5

Growth of an A. fumigantes mycetoma ball (mass of fungi) in a pre-existing lung cavity e.g., post-TB, old infarct, sarcoidosis, bronchiectasis or abscess

Question 6

What is the pathophysiology of allergic bronchopulmonary aspergillosis? (x3 mechanisms)

Answer 6

Aspergillus colonisation of the airways leading to IgE- and IgG-mediated immune responses. Airway damage and central bronchiectasis occurs from fungi (which release proteolytic enzymes and mycotoxins), CD4/Th2 cell responses (produce IL-4 and IL-5 and mediate eosinophilic inflammation), and IL-8 mediated neutrophilic inflammation.

Question 7

What is the pathophysiology of invasive aspergillosis?

Answer 7

Invasion of Aspergillus into lung tissue and fungal dissemination. Secondary to immunosuppression (e.g., neutropenia, steroids, haematopoietic stem cell/solid organ transplantation, AIDS).

Question 8

What is the epidemiology of aspergillosis?

Answer 8

Uncommon. Most common in elderly and immunocompromised.

Question 9

!!! What are the symptoms of aspergillosis – for each pathology?

Answer 9

• ASPERGILLOMA: asymptomatic, pleuritic chest pain (from peripheral lesions), haemoptysis
• ABPA: difficult to control asthma, recurrent episodes of pneumonia with wheeze, cough, fever and malaise
• INVASIVE ASPERGILLOSIS: dyspnoea, rapid deterioration, septic picture, nasal ulcer, skin rash (erythematous, slightly tender, raised lesion, single or multiple with a necrotic, often ulcerated, centre)

Question 10

What are the signs of aspergillosis – for each pathology?

Answer 10

• ASPERGILLOMA: tracheal deviation in large pathologies
• ABPA: dullness in affected lung, decreased breath sounds and wheeze
• INVASIVE ASPERGILLOSIS: pleural rub, cyanosis, sepsis signs (fever, pain, SOB, confusion)

Question 11

What are the investigations for aspergilloma? (x3)

Answer 11

• CXR: round opacity may be seen with a crescent of air around it (usually upper lobes)
• CT/MRI
• SPUTUM CULTURES: may be negative if no communication between cavity and bronchial tree. NB: Aspergillus is a common commensal coloniser in an abnormal respiratory tract

Question 12

What are the investigations for ABPA? (x5)

Answer 12

• CXR: transient patchy shadows (representing eosinophilic pneumonia), atelectasis (collapse from mucoid impaction), distended mucus-filled bronchi producing tubular shadows (‘gloved fingers’ appearance; see photo). Signs of complications: fibrosis in upper lobes, parallel-line shadows and rings (bronchiectasis).
• CT: lung infiltrates, central bronchiectasis
• LUNG FUNCTION TESTS: decreased lung volumes
• BLOODS: eosinophilia, raised serum IgE, raised serum specific IgE and IgG to A. fumigatus
• SKIN TEST REACTIVITY: immediate skin test reactivity to Aspergillus antigens

Question 13

What are the investigations for invasive aspergillosis? (x6)

Answer 13

• SPUTUM CULTURES: positive
• BRONCHOALVEOLAR LAVAGE: positive for Aspergillus and histological evidence of Aspergillus (septated hyphae with acute angle branching)
• BLOOD CULTURES: positive
• SERUM GALACTOMANNAN or BETA-D-GLUCAN ASSAY: positive. Both are constituents of Aspergillus cell walls.
• CXR: nodules surrounded by ground-glass opacity (halo sign) from haemorrhage into the tissue surrounding the area of fungal invasion, non-specific infiltrates, pleural-based lesions and cavities
• CT