PSORIASIS AND ARTHRITIS.

As early as 1822 interest was focused on the association of arthritis and psoriasis, when Alibert first reported its occurrence. In 1888 Bom-dillon produced the tirst detailed study in which the relation between the two was specifically examined. Since then numerous papers have been published, more particularly describing individual cases, in which the significance ofthe association has been debated. Until recent years, however, there has been no laboratory test which would distiuguisli between the two types of arthritis, uncomplicated rheumatoid arthritis and erosive arthi'itis with psoriasis, without taking the skin into aceonut. Siich a test was obviously necessary, since no clear cut clinical or radiograpliic picture of the erosive arthi'itis associated with psoriasis has been established. The advent of the Waaler-Rose Differential Agglutination Test (D.A.T.) for rheumatoid arthritis seems to have provided a solution, for this (lotects a specific abnormality in the serum of ni(;re thaii 80% of patients with rheumatoid arthritis {Brit. med. J., lOofi). It was the persistent absence of the \\ aaler-Rose phenomenon in the patients with psoriasis and arthritis seen before this study was started which first stimulated the writer's interest. The wide divergence of views shown in the literature about the association, and the scarcity of general surveys of the field, prompted a furtlier review of the question in the light of this finding.