[Case report of a patient with coexistent rheumatoid arthritis and ankylosing spondylitis].

In simultaneous conditions of inflammatory changes in peripheral joints and in sacroiliac joints, a differential diagnosis, amongst others, of rheumatoid arthritis with involvement of the sacro-iliac joints and also ankylosing spondylitis with peripheral joint involvement should be considered. It seems that in rare cases both diseases occur together. We describe one female patient with coexistence of rheumatoid arthritis and ankylosing spondylitis. The X-rays showed sacro-iliitis, syndesmophytes and inflammatory changes of the finger and toes, which are typical for rheumatoid arthritis. Rheumatoid factor was detected in serum and in synovial fluid. HLA B27 was negative. The results of 13 patients with coexistence of rheumatoid arthritis and ankylosing spondylitis reported in the literature since 1975, are compared with the above described patient.