[Psoriatic rheumatism. Prospective study of 50 cases, without sacroiliac involvement and without rheumatoid factor, compared with 50 cases of rheumatoid arthritis].

The authors report the results of a prospective study comparing 50 cases of psoriatic arthropathy with peripheral articular involvement only and negative rheumatoid serology with 50 cases of classical or definite rheumatoid arthritis paired according to sex, age and the duration of the disease. The results were studied using the X2 test of statistical significance. Despite frequent similarity with rheumatoid arthritis, psoriatic arthropathy differs from it significantly on the basis of a series of characteristics which may be summarised as follows: less wide dissemination and decreased severity of clinical and radiological articular lesions; more gradual progression by attacks separated by periods of remission, often total, resulting in less severe degree of invalidity than rheumatoid arthritis and therefore requiring less often the use of oral corticosteroids. The authors discuss the case of psoriatic arthropathy with positive rheumatoid serology and that of psoriatic arthropathy with combined peripheral and vertebral column involvement.