12th January 2024

Pulmonary aspergillosis

Pulmonary aspergillosis is a collective term which incorporates a number of distinct conditions caused by infection with an Aspergillus species. Aspergillus are widely distributed fungal moulds, and Aspergillus fumigatus is the most common species to cause human disease. The types of pulmonary aspergillosis, which will be discussed in more detail below, include:

• Allergic bronchopulmonary aspergillosis (ABPA)
• Aspergilloma
• Invasive aspergillosis

Allergic bronchopulmonary aspergillosis (ABPA)

ABPA is a hypersensitivity reaction to the colonisation of the lungs with an Aspergillus species. The hypersensitivity initially causes IgE-mediated bronchospasm and oedema of the bronchial wall. Ultimately, damage to the bronchial wall results in bronchiectasis. ABPA predominantly affects patients with asthma and cystic fibrosis and usually presents with deterioration of their underlying respiratory disease.

Presenting symptoms can include:

• Wheeze
• Fever
• Cough which may be productive
• Malaise

The diagnosis of ABPA is usually made on the basis of an asthma/atopy history and the following findings on investigations:

• Eosinophilia
• Raised Aspergillus-specific IgE
• Raised total IgE
• Positive Aspergillus skin prick test
• New infiltrates/evidence of bronchiectasis on chest X-ray or CT scan

The mainstay of management of ABPA is corticosteroids, with a long course required that is tapered off over weeks/months. Itraconazole may be added for some patients, especially in those who rebound during or after steroid tapering.

Aspergilloma

Aspergillomas are mass-like balls of the fungus, which typically arise in pre-existing pulmonary cavities. Classically, aspergillomas occur in the cavities of post-primary pulmonary tuberculosis (and therefore occur in the upper lobes). Other causes of pulmonary cavities, in which aspergillomas can form, include pulmonary sarcoidosis and PCP.

Usually, aspergillomas are asymptomatic, although cough and fever may be present. Haemoptysis can also be a presenting feature, which in some cases can be life-threatening if there is erosion of the aspergilloma into a bronchial artery.

The diagnosis of aspergilloma is usually made with a combination of radiological findings, on chest X-ray and CT, of a mass within a cavity and elevated serum precipitin (IgG) levels to Aspergillus species. The ‘air-crescent’ and Monod signs are often discussed in aspergilloma chest X-rays, which describe air surrounding an aspergilloma.

Asymptomatic patients usually do not require any treatment, although long-term itraconazole is sometimes used. Patients with symptomatic aspergillomas should be considered for surgical resection, yet this is often not possible due to insufficient respiratory reserve. In the setting of large-volume haemoptysis, selective bronchial artery embolism can be life-saving.

Image Source: Wikimedia Commons (2011). Aspergilloma_X-ray, Licensed under a creative commons licence. Available for free at: https://upload.wikimedia.org/wikipedia/commons/3/3a/Aspergilloma_X-ray_%285390379081%29.jpg (Accessed: 1 March 2022).

Invasive aspergillosis

Invasive aspergillosis is extremely rare in immunocompetent individuals and is most commonly seen in patients undergoing intensive chemotherapy or organ transplantation or those with advanced AIDS. The condition is rapidly progressive and carries a high morbidity and mortality. Angioinvasion is commonly seen, which leads to fungus spreading haematogenously and affecting extra-pulmonary organs, including the kidneys, brain and heart.

The diagnosis of invasive aspergillosis is challenging, and the diagnostic process can involve the following investigations:

• Chest X-ray and CT scanning which may show nodules, cavities or pulmonary infiltrates
• Sputum samples or samples from bronchoalveolar lavage can undergo culture or PCR. Galactomannan, which is a component of the cell wall of Aspergillus species, can also be assessed for in respiratory samples or in the serum
• Serum β-D-Glucan
• Aspergillus IgG levels

Voriconazole is the treatment of choice for invasive aspergillosis.