Background: Hypersensitivity pneumonitis (HP) is a complex syndrome due to an inflammatory response of the lungs to many aerosolized antigens. HP can be divided into acute, subacute, and chronic phenotypes, which frequently overlap. Case presentation: We describe the case of a non-smoker man admitted to the hospital for flu-like symptoms who presented emphysema as an evolution of HP. The diagnosis of HP was proposed by a multidisciplinary team based on the clinical/functional data and CT findings; two chest CTs were compared: a CT was performed during the hospitalization of the patient and a CT had been performed 5 years before. The diagnosis was confirmed through a lung biopsy. Examining the patient history, a domestic exposition to pigeons and poultry was revealed. Conclusion: HP can lead to emphysema instead of fibrosis. This atypical evolution of HP should be known by clinicians and radiologists in order to suspect it and promptly start the correct diagnostic workup.

Keywords: Hypersensitivity pneumonitis, pulmonary emphysema, multidisciplinary group of interstitial lung disease consult, high-resolution computed tomography, surgical lung biopsy.