Archived case 204 · June 6-June 13, 2016
62-year-old man; non-smoker Poorly controlled asthma >10 years. Chronic cough productive of thick white sputum. No fevers or chills.
Describe the pertinent radiologic findings. What is your differential diagnosis and leading diagnosis?
PA (Fig. 1A) and lateral (Fig. 1B) chest radiographs demonstrate pulmonary hyper-expansion and branching tubular-like opacities emanating out from the perihilar regions into the upper and lower lobes. Some opacities form an inverted ‘V” or “Y” shaped morphology. On closer inspection, these opacities represent mucoid filled or impacted bronchiectatic airways. Answer Diagnosis: Allergic Bronchopulmonary Aspergillosis (ABPA)
Allergic Bronchopulmonary Aspergillosis (ABPA)
Differential Diagnosis
· Bronchiectasis of Other Etiologies
Discussion
Allergic bronchopulmonary aspergillosis (ABPA) is also known as allergic bronchopulmonary fungal disease, since species other than Aspergillus are sometimes implicated. Typically, Aspergillus fumigatus colonizes the airway lumen in patients with asthma. The retained bronchial secretions initiate immune complex and complement formation with resultant tissue injury. Acutely, the injury may manifest as transient subsegmental or lobar consolidation. Chronic changes damage the larger bronchi and produce central bronchiectasis, which is the imaging hallmark of ABPA. Affected patients typically have diffuse disease at the time of diagnosis, manifesting as central cystic and/or varicose bronchiectasis involving both lungs. ABPA is caused by type I and type III (IgE and IgG) immunologic responses to the fungal (usually Aspergillus) species in the airway lumen. Excessive mucous production and abnormal ciliary function result in mucoid impaction.
Clinical Presentation
Affected patients may present with recurrent wheezing, malaise, low-grade fever, cough, sputum production and chest pain. ABPA typically affects patients with asthma but also occurs in 2-5% of patients with cystic fibrosis. Patients with ABPA characteristically have blood and sputum eosinophilia and elevated total serum IgE. Serum levels of IgE may be used to confirm the diagnosis and acute exacerbations of the disease.
Imaging Features
Radiography
· Central (proximal) bronchiectasis predominantly involving the upper lobes
· Parallel linear opacities and ring shadows (central and upper zone predominance)
· Tubular opacities from mucoid impaction
· Atelectasis in 50% of patients (single lobe; multiple lobes; entire lung)
MDCT / HRCT
· Central bronchiectasis, often severe and widespread
· Mucoid impaction that may exhibit high-attenuation mucous (30%) and occasional calcification
· Bronchial wall thickening
· Linear or branching centrilobular opacities (tree-in-bud)
· Air-fluid levels within dilated bronchi; may indicate infection
· Peripheral consolidation or diffuse ground-glass opacity (subacute)
· Atelectasis
· Air-trapping on expiration
Treatment
· Corticosteroids
Prognosis
· Resolution of acute disease
· Prevention of disease progression with corticosteroid therapy
· Recurrence
Selected Readings
1. Franquet T, Müller NL, Oikonomou A, et al. Aspergillus Infection of the Airways: Computed Tomography and Pathologic Findings. J Comput Assist Tomogr 2004; 28:10-16.
2. Kumar R. Mild, Moderate, and Severe Forms of Allergic Bronchopulmonary Aspergillosis: A Clinical and Serologic Evaluation. Chest 2003; 124: 890-892.
3. Mitchell TA, Hamilos DL, Lynch DA, et al. Distribution and Severity of Bronchiectasis in Allergic Bronchopulmonary Aspergillosis (ABPA). J Asthma 2000; 37:65-72.
4. Parker MS, Rosado de Christenson ML, Abbott GF . Allergic Bronchopulmonary Disease. In: Chest Imaging Case Atlas 2nd edition. Thieme New York; 2012: pp171-174.
Original case written by its authors at Virginia Commonwealth University and published at this address as part of a weekly teaching collection. Reproduced here as an archive.