MUC5AC and monoclonal gammopathy: According to Rongioletti et al.,2, 3 the diagnostic criteria are: generalized papular and sclerodermiform rash, mucin deposition in the upper dermis, fibroblast proliferation and collagen fiber thickening, monoclonal gammopathy (90% monoclonal gammopathy of undetermined significance [MGUS]) and normal thyroid function.