aspergillus lung disease

Question 1

definition

Answer 1

Lung disease associated with Aspergillus fungal infection.

Question 2

how it works

Answer 2

Inhalation of the ubiquitous Aspergillus (usually Aspergillus fumigates) spores can produce three different clinical pictures:

1. Aspergilloma: Growth of an A.fumigatus mycetoma ball in a preexisting lung cavity (e.g. post-TB, old infarct or abscess).
2. Allergic bronchopulmonary aspergillosis (ABPA): Aspergillus colonization of the airways (usually in asthmatics) leads to IgE- and IgG-mediated immune responses. Proteolytic enzymes and mycotoxins released by fungi, CD4/Th2 cells producing IL-4 and IL-5 and mediating eosinophilic inflammation, and IL-8 mediated neutrophilic inflammation result in airway damage and central bronchiectasis.
3. Invasive aspergillosis: Invasion of Aspergillus into lung tissue and fungal dissemination. Secondary to immunosuppression (e.g. neutropaenia, steroids, haematopoietic stem cell/ solid organ transplantation, AIDS).

Question 3

symptoms

Answer 3

Aspergilloma: Asymptomatic, haemoptysis, which may be massive.
ABPA: Difficult to control asthma, recurrent episodes of pneumonia with wheeze, cough,
fever and malaise.
Invasive aspergillosis: Dyspnoea, rapid deterioration, septic picture.

Question 4

signs

Answer 4

Tracheal deviation in large aspergillomas.
Dullness in affected lung, reduced breath sounds, wheeze (in ABPA).
Cyanosis may develop in invasive aspergillosis.

Question 5

investigations

Answer 5

Aspergilloma:
CXR: Round opacity may be seen with a crescent of air around it (usually in the upper lobes).
CT or MR imaging if CXR does not clearly delineate a cavity.
Cultures of the sputum may be negative if there is no communication between the cavity and the bronchial tree.
Also Aspergillus is a common colonizer of an abnormal respiratory tract.

ABPA:
- Immediate skin test reactivity to Aspergillus antigens.
- Eosinophilia.
- raised Serum total IgE.
- raised Serum specific IgE and IgG to A. fumigatus or precipitating serum antibodies to A.
fumigates.
CXR: Transient patchy shadows, collapse, distended mucus-filled bronchi producing tubular
shadows (‘gloved fingers’ appearance). Signs of complications: Fibrosis in upper lobes
(similar to tuberculosis), parallel-line shadows and rings (bronchiectasis).
CT: Lung infiltrates, central bronchiectasis.
Lung function tests: Reversible airflow limitation, # lung volumes/gas transfer in progressive
cases.

Invasive aspergillosis:
- Detection of Aspergillus in cultures or by histologic examination
(septated hyphae with acute angle branching). Diagnosis may be made in patients with risk factors, suggestive clinical findings and microscopic evidence of septate hyphae on examination of either bronchoalveolar lavage fluid or sputum or a positive serum galactomannan or beta-D-glucan assay (constituents of Aspergillus cell walls).
Chest CT scan may show nodules surrounded by a ground-glass appearance (halo sign) in invasive pulmonary aspergillosis (haemorrhage into the tissue surrounding the area of fungal invasion).