Psoriatic arthritis was described as a distinct rheumatic disease in the 1960s, and subsequently grouped among the spondyloarthropathies. Recently, other rheumatic manifestations of psoriasis, such as enthesopathy and osteoperiostitis, were recognized. This study attempts to examine the rheumatological and radiological manifestations of Psoriasis and their association with skin and nail disease. Eighty-one psoriatic outpatients were interviewed consecutively during 6 months. Questionnaires and indices were carried out to assess the extent and severity of skin and nail involvement, as well as the activity and severity of peripheral and axial rheumatic manifestations. Radiological examination of the hands, feet, spine and pelvis was also done for all patients. Fifty-nine psoriatic outpatients (73%) had rheumatic manifestations clinically and/or radiologically (Psoriatic arthropathy "PsA"). Clinical peripheral arthritis was found in 14 (23.7%) of the patients with PsA, being oligoarticular in 11, polyarticular in two, and exclusively of the distal interphalangeal (DIP) joints in one patient. Sacroiliitis and/or spondylitis were found in 38 (64.4%), enthesopathy in 36 (61%), dactylitis in two (3.3%), radiological DIP involvement in 24 (40.6%), and radiological osteoperiostitis in 49 (83%) of patients with PsA. Most PsA patients had more than one rheumatic manifestation, while four patients (6.7%) had isolated enthesopathy without any other rheumatic manifestations. Subungual hyperkeratosis of the nails was significantly correlated with PsA (p<0.05), as well as with clinical arthritis, enthesopathy, and DIP involvement (p<0.01), while other types of skin and nail lesions were correlated with selected rheumatic manifestations. The performance of existing criteria for PsA was poor, as individual sets favored either sensitivity or specificity. Psoriatic arthropathy (PsA), occurring in about three-quarters of hospital outpatients with psoriasis, is more common than previously thought. More sensitive and specific criteria for the diagnosis and classification of PsA need to be developed, taking into account the recently described clinical and radiological manifestations. © Clinical Rheumatology 2006.
