17th January 2024

Differentials 

ABPA is a rare condition; however, the clinical presentation and imaging may be misleading and equally suggestive of other conditions also. The list below details some of the main differentials to consider when working a patient up for a possible diagnosis of ABPA.

• Eosinophilic pneumonia – this condition is more common in non-smoking women and not specific to the asthma or CF population. A chest X-ray may show bilateral infiltrates peripherally, and a biopsy would show alveolar eosinophils with minimal fibrosis.
• Eosinophilic granulomatosis with polyangiitis (EGPA) – EGPA is a type of vasculitis rather than a hypersensitivity condition; therefore, other organ systems are involved and contribute to the clinical presentation, whereas ABPA presents with purely respiratory symptoms.
• Severe asthma or CF exacerbation alone – haemoptysis would be unlikely, a skin prick test for Aspergillus fumigatus would be negative, serum IgE would not be elevated (unless the patient is on oral steroids), and specific IgE and IgG for Aspergillus fumigatus would not be elevated. 
• Parasite infection – acute eosinophilia on blood testing could be indicative of parasitic infection and should be explored if symptoms and signs do not fit with ABPA. Infectious disease opinion may be needed.