B43-42 A Tale of Misleading Markers

Abstract Sjogren’s syndrome (SS) is an autoimmune condition primarily affecting exocrine glands. Extraglandular manifestations include pleural effusions, interstitial lung disease, and hypercoagulability. Elevated pleural fluid adenosine deaminase (ADA) is typical in tuberculous pleurisy but can occur in autoimmune diseases like SS, leading to diagnostic confusion. 85-year-old male with hypertension, hyperlipidemia, hypothyroidism presented with 10-days of dyspnea and malaise with recent travel to Southeast Asia. Computed tomography angiography (CTA) chest demonstrated bilateral infiltrates and pleural effusions. Ceftriaxone and doxycycline were started. Thoracentesis demonstrated exudative effusion with lymphocyte predominance and elevated pleural ADA (49.3 U/L). Cultures and cytology were negative. Serum histoplasmosis, blastomycosis, QuantiFERON-TB Gold, Acid-fast bacilli (AFB) smears were negative. Bronchoscopy with bronchoalveolar lavage (BAL) had negative cultures. Antibiotics were switched to levofloxacin 750mg for 7 days with concern for latent TB and he was discharged home. 3 weeks after discharge he had worsening dyspnea. CTA chest revealed acute bilateral pulmonary embolisms (PE) with right heart strain, persistent bilateral infiltrates, and recurrent pleural effusions. Heparin drip was started. Repeat thoracentesis showed similar findings. Cytology was negative for malignancy. ADA decreased (12 U/L). Autoimmune workup revealed positive ANA (>1:1280) and SSA antibody (>240 U/mL) consistent with primary SS. CT-guided lung biopsy was obtained, demonstrating benign alveolar tissue with nonspecific chronic inflammation without malignancy. Heparin was transitioned to apixaban. AFB and fungal cultures were negative. Given negative malignancy and infectious testing, oral steroids were started for organizing pneumonia from SS with sulfamethoxazole-trimethoprim and famotidine for prophylaxis. He followed up outpatient with pulmonology and rheumatology with muscle weakness. Creatine phosphokinase, ALT, and AST was elevated. Additional testing for connective tissue disease was negative. His symptoms improved with continued steroids. Azathioprine 50mg daily was started with steroids tapering. Muscle enzymes improved along with strength and pain. Azathioprine was increased to 50mg twice daily. CTA chest was negative for PE and had improvement of consolidations from prior hospitalization. EMG was ordered for further evaluation of weakness and steroids were rapidly tapered. Elevated pleural ADA (>40 U/L) is sensitive for TB pleurisy but non-specific. ADA of 49.3 U/L, lymphocytic effusion, and travel history raised TB suspicion. Negative AFB, cultures, QuantiFERON, and ADA normalization (12 U/L) with positive SS serologies confirmed autoimmune etiology. The PE likely resulted from SS-associated hypercoagulability. Lung biopsy with nonspecific inflammation supported SS-related organizing pneumonia. This underscores the need for comprehensive autoimmune evaluation in ADA-positive effusions with negative infectious workup. This abstract is funded by: None