Psoriatic Arthritis: A Roentgenologic Study

The concept that psoriatic arthritis is a distinct clinical entity has been endorsed by many, questioned by some, and rejected by others. A considerable number of authors are of the opinion that changes in the joints of patients with psoriasis are indistinguishable from those of rheumatoid arthritis and that unusual cases are atypical forms of the latter disease. On the other hand, psoriatic arthritis has been distinguished clinically from ordinary rheumatoid arthritis in many respects, particularly in the involvement of the distal interphalangeal joints together with concurrent activity of arthritis and psoriasis of the nails and skin, and the usually good response to therapy in early cases. The concept that psoriatic arthritis is a distinct clinical entity has been endorsed by many, questioned by some, and rejected by others. A considerable number of authors are of the opinion that changes in the joints of patients with psoriasis are indistinguishable from those of rheumatoid arthritis and that unusual cases are atypical forms of the latter disease. On the other hand, psoriatic arthritis has been distinguished clinically from ordinary rheumatoid arthritis in many respects, particularly in the involvement of the distal interphalangeal joints together with concurrent activity of arthritis and psoriasis of the nails and skin, and the usually good response to therapy in early cases. Because the joints are simple structures with only limited patterns of response, the early manifestations of various forms of arthritis may look alike clinically and roentgenologically. The articular cartilage may be damaged, narrowing the joint space. The synovial membrane may be thickened, and the margins of subchondral bone eroded, without any distinguishing change being present. Until the joint has become severely affected, one may not be able to distinguish different forms of arthritis. The characteristic manifestations of psoriatic arthritis are seen most clearly in far-advanced cases and these can be easily separated from cases of rheumatoid arthritis. In 231 of 7,280 cases of arthritis encountered at the Mayo Clinic from 1949 through 1953, an associated diagnosis of psoriasis was made. Roentgenograms of the hands, feet, and other joints were available in 175 of these. The records of the 175 patients were reviewed in detail, and the films were studied and classified according to the predominance of certain changes in the hands and feet and large joints, including the sacroiliac joints. In 20 cases in which there were clinical signs of arthritis, there was no roentgen evidence of the disease, or evidence only of osteoarthritis. These cases, therefore, were not considered further. This left 155 cases for this study.