For the positive diagnosis of SM, Rongioletti and Rebora proposed the following criteria in 2001 [4]: (i) A clinical examination of a generalized papular and sclerodermoid eruption, (ii) A cutaneous histological examination revealing mucin deposits in the reticular dermis, fibroblastic proliferation, and fibrosis, (iii) The presence of serum monoclonal gammopathy, and (iv) The absence of thyroid pathology. This evidence concerns the gene MUC5AC and monoclonal gammopathy.