Allergic bronchopulmonary aspergillosis as an initial manifestation of cystic fibrosis: Diagnostic and therapeutic implications in the era of CFTR modulators.

Allergic bronchopulmonary aspergillosis (ABPA) results from complex hypersensitivity reactions to Aspergillus fumigatus, which often occur in patients with asthma, cystic fibrosis (CF), or CF transmembrane conductance regulator (CFTR)-related disorders. Genetic predisposition, particularly variants of the CFTR gene, probably plays a significant role in the development of ABPA. We present the case of a 20-year-old male with ABPA and bronchiectasis that was initially misdiagnosed as a result of normal sweat chloride values and negative first-level genetic testing results. Comprehensive CFTR gene sequencing revealed 2 pathogenic variants, R347H and D1152H, which together with the clinical phenotype and functional tests, supported the diagnosis of CF. Treatment with elexacaftor/tezacaftor/ivacaftor resulted in significant clinical and functional improvement, including a marked decrease in total IgE levels, suggesting a potential role for CFTR modulators in controlling ABPA. This case illustrates the evolving understanding of CF as a spectrum of disorders in which CFTR dysfunction may manifest subtly and variably, necessitating a high index of suspicion and a comprehensive diagnostic approach to ensure timely treatment in the era of highly effective CFTR modulators.