Juvenile psoriatic arthritis.

From two studies (Lambert et al, 1976; Shore and Ansell, 1982), it was concluded that juvenile psoriatic arthritis is a distinct entity with one group of patients virtually indistinguishable from those with juvenile chronic arthritis initially, while all the patterns of psoriatic arthritis recorded in adults were seen in the remainder. A family history of psoriasis occurs in about half the patients, and one of arthritis in 20%. A swollen tendon sheath of a single finger or toe associated with synovitis in two or three joints of the digits is highly characteristic. Accurate diagnosis is important because these patients tend to go on to develop an asymmetrical destructive polyarthritis. This needs to be recognized early to utilize effective slow-acting drugs. Southwood and colleagues (1989) have defined two quite distinct groups of juvenile psoriatic arthritis: those young at onset, who are usually girls, and those in adolescence, who are more frequently boys. It is possible that there are other variants, including girls aged 8-10 years with a polyarthritic onset who may go on to develop arthritis mutilans. The concept of 'probable juvenile psoriatic arthritis' is supported by follow-up, in that a significant proportion of such patients do pass into the definite group. It is highly desirable that the suggested Vancouver criteria are validated by a long-term prospective study, which will probably need to be multicentred to ensure that the subgroups are large enough for satisfactory conclusions to be drawn. In the management of this serious arthritis in childhood, it is important to consider long-acting drugs early, before undue damage to joints has occurred. Again, multicentre studies are needed to determine which is the most useful. Presently, methotrexate appears to be the drug of choice.