Clinical experience in 115 patients with arthritis and/or enthesitis who met the classification criteria for psoriatic arthritis (CASPAR) within the last two years-Possible association with malignant disorders.

Among about 400 patients with active arthritis and/or enthesitis who were referred to our department within the last two years, 140 of them were strongly suspected as having psoriatic arthritis by a comprehensive diagnostic procedure and after consulting specialists from dermatology, orthopedics, and radiodiagnostics at our institution and other institutions. Among them, 115 patients strictly met the classification criteria for psoriatic arthritis (CASPAR). Among the 115 patients, 19 patients (9 males and 10 females) had current psoriasis and 96 patients (22 males and 74 females) did not have current psoriasis. Nineteen (16.5%) of the 115 patients had developed malignant tumor before the onset of arthritis, and 4 (3.5%) developed malignant tumor after the onset of arthritis. Twenty-two of the 23 patients who developed malignancy were female and 10 patients developed breast cancer. Differential diagnoses in these 23 patients may include paraneoplastic syndrome. We consider that it is important to take into account the possibility of paraneoplastic syndrome in patients with arthritis and/or enthesitis who apparently meet the CASPAR criteria, and detailed screening and monitoring of malignant disease may be beneficial to the patients.