MUC5AC and diabetes mellitus: The histopathologic features of scleroedema adultorum of Buschke in patients with diabetes mellitus include thickened collagen bundles within the reticular dermis separated by mucopolysaccharides (mainly mucin) containing fenestrations (Fig. 2a and b) Fibroblasts of the reticular dermis produce an excessive amount of mucin (heavily glycosylated high-molecular weight proteins) and collagens.