New and emerging conditions of acquired cutaneous mucinoses in adults

Cutaneous mucinoses are a heterogenous group of conditions, characterized by the deposition of glycosaminoglycans (mucin) in the dermis, follicles, or in the epidermis. Major cutaneous mucinoses include lichen myxedematosus, scleredema, mucinoses associated with thyroid disease, reticular erythematous mucinosis, papulonodular mucinosis associated with connective tissue diseases, and cutaneous focal mucinosis. The aim of this review is to provide an update of what has currently been reported in the last 30-year literature about several new or emerging conditions of acquired cutaneous mucinoses in adults. Two new clinico-pathologic entities have been described: (i) Obesity-associated lymphedematous mucinosis and pretibial stasis mucinosis; (OACM) (ii) Nodular mucinosis of the breast (NMB). Two relatively new disease categories encompassing cutaneous mucinoses with a common pathogenetic mechanism have been identified: (i) Cutaneous mucinoses associated with drug exposure including biologic therapy, anti-colony-stimulating factor 1 receptor (CSF1R) and subcutaneous intralesional interferons (toxic dermal mucinoses); (ii) Cutaneous mucinosis following physical agents including mechanical traumas and after knee replacement.