Primary Sjögren's syndrome complicated by pleuritis and pleural effusion: a case report and review of the literature.

Introduction and importance: Pleural effusion is a rare manifestation of primary Sjögren's syndrome (pSS), especially in elderly patients with comorbidities such as hypothyroidism and chronic obstructive pulmonary disease (COPD). Diagnosis can be challenging as respiratory symptoms may mimic community-acquired pneumonia or COPD exacerbations. Reporting rare presentations aids early recognition and tailored management. Case presentation: An 82-year-old woman with pSS, hypothyroidism, and COPD presented with progressive dyspnea, productive cough, and bilateral leg swelling. Chest X-ray posteroanterior view revealed consolidation with blunting of the left costophrenic angle, pointing toward pleural effusion. Subsequent pleural fluid analysis demonstrated lymphocyte predominance along with normal glucose levels, suggesting effusion due to pSS. She received empiric antibiotics, oxygen, and supportive care. Clinical discussion: Common causes of pleural effusion in an elderly patient include cardiovascular conditions such as heart failure, malignancy, infections such as pneumonia and tuberculosis, and autoimmune diseases such as systemic lupus erythematosus or rheumatoid arthritis. Sjögren's syndrome rarely causes pleural effusion. Pleural fluid analysis helps in differentiating the cause of effusion. In pSS, pleural fluid analysis reveals lymphocytic predominance and exudation with normal glucose levels and pH, and low pleural fluid adenosine deaminase levels. Conclusion: This case underscores the importance of thorough evaluation, early recognition, and tailored management in pSS patients with respiratory symptoms to prevent misdiagnosis and improve outcomes.