Ankylosing spondylitis is a chronic seronegative spondyloarthropathy, which results in ankylosis of the spine and sacroiliac joints, although involvement is also seen in large and small joints. AS is a chronic, multisystem inflammatory disease of unknown etiology. HLA- B27 is the gene with the strongest association. Although classically thought of as a spinal disease, it can also involve other organs, such as the eyes, lungs, and heart. Pleuroparenchymal involvement is uncommon and is seen in the later stages of the disease. Pulmonary involvement in AS is usually in the form of upper lobe fibrocavitary disease