Development of MGUS in psoriatic patients: a possible undiagnosed event during anti‐TNF‐α‐treatment

Background Monoclonal gammopathies are haematological conditions characterized by the clonal proliferation of plasma cells which produce a monoclonal immunoglobulin that accumulates in the blood. They have already been reported during treatment with a range of drugs but never before during treatment with the anti-TNF-α treatments: adalimumab, etanercept and infliximab currently used in the therapy of moderate-severe psoriasis and psoriatic arthritis. Objective This is a case series describing the development of MGUS in psoriatic patients treated with anti-TNF-α. Methods Three hundred patients receiving an anti-TNF-α treatment for chronic plaque psoriasis or psoriatic arthritis in a clinical setting in Italy, These patients were screened through serum protein electrophoresis to investigate the possible development of MGUS. Results Eight patients were found to have developed monoclonal gammopathy of undetermined significance. The median treatment duration for the eight patients was 1 year with excessive IgG present in five patients, IgM accumulation in one patient and a double monoclonal component in two patients. Conclusion Our data suggest that there may be an association between anti-TNF-α therapy and development of MGUS. © 2011 European Academy of Dermatology and Venereology.