[The hand in psoriatic arthropathy. Radiographic and xeroradiographic comparison].

The hands of 45 cases of psoriasis with arthritis and of 100 cases of rheumatoid arthritis without psoriasis were studied by radiographic and xerographic techniques. The characteristic findings of both methods were recorded separately and compared later. In 44% of cases of psoriatic arthritis, radiographic and xerographic changes are indistinguishable from typical rheumatoid arthritis, but with predominant involvement of distal interphalangeal joints, often bilaterally asymmetric. On the contrary, in 31% of cases, erosive polyarthritis associated with proliferation of subperiosteal new bone (enthesopathy) is present, also with characteristic feature of arthritis mutilans. In 25% of cases, psoriasis of the skin and/or nails is associated with clinical manifestations of rheumatoid arthritis, without roentgenographic findings of arthropathy. The xerographs and radiographs of each patient were compared, assessing the degree of subperiosteal erosion, soft tissue swelling, acro-osteolysis, distruction of small joints and osteolysis of the phalanges, bony ankylosis. The soft tissue swelling ("sausage" finger) was more easily demonstrated by xeroradiography than by conventional radiography, because of its wide recording latitude. However, radiograph remains the technique of choice in the assessment of bone changes of the hand, especially at the first stage of arthritides.