A case of Sjögren's syndrome in which diffuse cystic lung lesions led to an accurate diagnosis.

Key Clinical Message:Even in the absence of other symptoms or other pulmonary manifestations suggesting Sjögren's syndrome (SS), it is necessary to include SS in the differential diagnosis of diffuse cystic lung disease (CLD). Abstract:A case of SS that presented initially with diffuse CLD is reported. This case is considered rare because diffuse pulmonary cysts were observed in the early stage with few symptoms, only cysts were observed without other lung lesions on imaging, cyst formation was histologically considered to be alveolar loss, and airway lesions not observed on imaging were suspected based on lung function testing. The details of this case provide extremely important information to consider for the diagnosis and management of CLD and SS.