A case of suspected Sjögren's disease-associated pleuritis in a very elderly patient.

A 90-year-old woman presented with an antibiotic-resistant fever and right-sided pleural effusion. Pleural fluid analysis revealed exudative effusion without identifiable pathogens. Sjögren's disease (SjD) was diagnosed based on anti-SS-A/SS-B antibody positivity and labial salivary gland biopsy findings. Pleural effusion was suspected to be associated with SjD, although a definitive causal relationship could not be established. The timing of SjD onset remained uncertain; however, pleural effusion as the initial manifestation is rare. This represents the oldest reported case in which SjD-associated pleuritis is suspected and is extremely rare in individuals aged ≥90 years.