[Reversed halo sign as imaging manifestation of primary Sjögren's syndrome with nonspecific interstitial pneumonia].

The reversed halo sign (RHS), also referred to as the atoll sign, represents a distinct imaging finding that was initially characterized in cryptogenic organizing pneumonia and has subsequently been observed in instances of fungal infections, tuberculosis, vasculitis, and tumor pathologies.This case report details the presentation of a patient with primary Sjögren's syndrome and non-specific interstitial pneumonia, who on imaging displayed the RHS-a relatively infrequent finding. Subsequent confirmatory testing, including anti-nuclear antibody panel, lip gland biopsy, and lung biopsy, ultimately confirmed the diagnosis.This case highlights the importance for clinicians considering laboratory investigations and histopathological assessments when imaging results and inconsistent with the clinical picture, aiming to avert misdiagnosis and subsequent mismanagement.