Monoclonal IgG immunoglobulinemia with subsequent myeloma in psoriatic arthritis

A 42-year-old man had suffered from skin psoriasis for 27 years, psoriasis arthritis for 6 years and corneal crystalline deposits for 1 year, when an IgG-kappa monoclonal immunoglobulin was detected in his serum electrophoretic pattern. All the diagnostic studies for multiple myeloma were negative. However, 16 months later he developed this disease.