The radiographic features of rheumatoid arthritis in HLA-B27-positive patients.

Radiographs were reviewed in a group of nine patients with classical seropositive rheumatoid arthritis who on tissue typing were found to express the class I HLA-B27 allele. Radiographs were analyzed with regard to whether or not they demonstrated radiographic features of (1) classical rheumatoid arthritis, (2) seronegative arthritis, or (3) mixed features of rheumatoid and seronegative arthritis. Five patients (55%) displayed radiographic features consistent with a diagnosis of rheumatoid arthritis, two patients (22%) showed radiographic features of seronegative disorder (periostitis and sacroiliitis), and two patients (22%) showed a mixed picture with evidence of both rheumatoid arthritis and a seronegative disorder. Thus, the HLA-B27 allele contributed to the radiographic features in 44% of patients with rheumatoid arthritis and associated HLA-B27. Thus, the wide range of findings in our population indicates that the radiographic attributes are not specific enough to constitute a unique subpopulation of patients with rheumatoid arthritis.