Isolated Pleural Effusion in a Patent With Ankylosing Spondylits and His Dramatc Response to Prednisolone

Ankylosing Spondylitis (AS) is a chronic inflammatory disease of the skeleton manifested by back pain and progressive stiffness of the spine. In AS, the inflammation starts around the enthesis (the site of ligament insertion into bone) and typically affects young men with a peak age of onset of 20 to 30 years. Although classically thought as a spinal disease, it can involve other organs such as eyes, lungs, and heart. We present a 49-year-old man with pleural effusion and history of recent pericardial effusion but his fluid studies of pleura and pericardium did not lead us to a clear diagnosis. Then we noticed his thoracic kyphosis, severe restriction of lumbar movements and sacroiliac joint inflammation on MRI which are suggestive of AS. We started prednisolone 50 mg daily for one week and the pleural effusion resolved spontaneously after one week. Then, we tapered prednisolone and the patient remained well off any medication. Isolated pleural and or pericardial effusion may be seen in patients with AS without a simultaneous apical fibrobullous involvement of the lungs and it responds well to corticosteroid.