In 27 (18 ) patients, lesions were confined to the palms and soles. OBJECTIVE: Our objective was to review the risk of malignancy associated with therapies for moderate to severe psoriasis, including phototherapy, traditional systemic therapies, and biologic therapies. Because of the substantial lack of clinical data, the majority of studies evaluated focus on the treatment of patients with rheumatoid arthritis, which is a systemic inflammatory disorder comparable to psoriasis. Although autoimmune diseases are relatively common, mechanisms that lead to their development remain largely unknown. Psoriatic arthritis (PsA) is a chronic systemic inflammatory disease characterized by joint inflammation associated with cutaneous psoriasis.