A 45-year-old woman presents with chronic lower back pain that worsens at night and improves with exercise. She also reports a history of alternating buttock pain. Examination reveals decreased lumbar flexibility. What are the possible causes and the next steps?
This patient's symptoms are suggestive of ankylosing spondylitis, a type of inflammatory arthritis that primarily affects the spine. The next steps should involve blood tests including HLA-B27 antigen and inflammatory markers like CRP or ESR, as well as imaging studies such as X-ray or MRI of the spine. Management typically includes NSAIDs, physical therapy, and possibly disease-modifying antirheumatic drugs (DMARDs) or biologics.