Coexistence of ankylosing spondylitis and systemic lupus erythematosus.

Coexistence of ankylosing spondylitis with connective tissue diseases is uncommon. We describe here the coexistence of ankylosing spondylitis and systemic lupus erythematosus in a 35-year-old man. He presented with a 4-year history of pain in the hip joint and lower spine, and he later developed a malar rash and discoid rash. Immunological tests revealed that antinuclear antibody and double stranded DNA antibody were positive. The human leukocyte antigen B27 antigen was also found to be positive. We propose that development of systemic lupus erythematosus in this case may have been due to low grade chronic inflammation.