Allergic Bronchopulmonary Aspergillosis: A Perplexing Clinical Entity

Abstract

In susceptible individuals, inhalation of Aspergillus spores can affect the respiratory tract in many ways. These spores get trapped in the viscid sputum of asthmatic subjects which triggers a cascade of inflammatory reactions that can result in Aspergillus-induced asthma, allergic bronchopulmonary aspergillosis (ABPA), and allergic Aspergillus sinusitis (AAS). An immunologically mediated disease, ABPA, occurs predominantly in patients with asthma and cystic fibrosis (CF). A set of criteria, which is still evolving, is required for diagnosis. Imaging plays a compelling role in the diagnosis and monitoring of the disease. Demonstration of central bronchiectasis with normal tapering bronchi is still considered pathognomonic in patients without CF. Elevated serum IgE levels and Aspergillus-specific IgE and/or IgG are also vital for the diagnosis. Mucoid impaction occurring in the paranasal sinuses results in AAS, which also requires a set of diagnostic criteria. Demonstration of fungal elements in sinus material is the hallmark of AAS. In spite of similar histopathologic features, co-existence of ABPA and AAS is still uncommon. Oral corticosteroids continue to be the mainstay of management of allergic aspergillosis. Antifungal agents play an adjunctive role in ABPA as they help reduce the fungal load. Saprophytic colonization in cavitary ABPA may lead to aspergilloma formation, which could increase the severity of the disease. The presence of ABPA, AAS, and aspergilloma in the same patient has also been documented. All patients with Aspergillus-sensitized asthma must be screened for ABPA, and AAS should always be looked for.

Keywords: Allergic Aspergillus sinusitis; Aspergillus; allergic bronchopulmonary aspergillosis; allergic fungal sinusitis; aspergilloma; asthma.

Fig. 1. Plain chest roentgenogram showing a left-sided perihilar opacity along with non-homogeneous infiltrates in all zones of both lung fields.

Fig. 2. Plain chest roentgenogram of the same patient taken 4 months later showing spontaneous resolution of the left-sided perihilar opacity. The bilateral non-homogeneous infiltrates have increased considerably. (Figs 1 and 2 reveal 'transient pulmonary infiltrates' or 'fleeting shadows', which are characteristic of ABPA.)

Fig. 3. Computed tomography of the thorax showing 'signet ring' (short, thick arrow) and 'string of pearls' (long, thin arrow) appearances, indicative of central bronchiectasis. Mucoid impaction and dilated bronchi are also visualized.

Fig. 4. Computed tomography of the thorax showing 'signet ring' (short, thick arrow) and 'string of pearls' (long, thin arrow) appearances, indicative of central bronchiectasis. Mucoid impaction and dilated bronchi are also visualized.

Fig. 5. Computed tomography of the paranasal sinuses showing hyperdense lesions in the ethmoid and maxillary sinuses bilaterally, suggestive of inspissated secretions.