A Rare Cause of Pleural Effusion: Ankylosing Spondylitis

Ankylosing spondylitis (AS) is a seronegative spondyloarthropathy involving the axialskeleton and major joints. Pleuropulmonary involvement is rare manifestation of ASmostly presented as apical fibrobullous disease and pleural thickening. Herein, we re-port a rare case with right sided pleural effusion in a male patient that was determinedon a chest x-ray performed routinely before initiation of anti-TNF therapy. Pleural effusion was a lymphocytic exudate with a normal glucose level. The histopathologi-cal examination of closed pleural biopsy revealed nonspecific chronic inflammato-ry cell infiltration. The patient was followed up with etanercept treatment. One yearafter the initiation of therapy, due to persistent pleural effusion, video assisted thoracoscopic surgery was performed. Pleural biopsies were also consistent with chronic inflammation.