The cutaneous mucinoses are a heterogeneous group of disorders whose main characteristic is abnormal mucin deposition in the skin. The aetiopathogenesis of cutaneous mucinoses is unknown, although cytokines such as tumour necrosis factor α and β, interleukin 1, interleukin 6 and transforming growth factor β and/or polyclonal and monoclonal immunoglobulins and other unidentified factors in the serum of affected patients may induce up‐regulation of glycosaminoglycan synthesis. The cutaneous mucinoses are divided into two categories: (i) primary cutaneous mucinoses in which the mucin deposit is the main histological feature resulting in clinically distinctive lesions; and (ii) secondary mucinoses in which the mucin deposition is only an additional histological epiphenomenon. Primary mucinoses can be divided into dermal and follicular mucinoses. The former includes lichen myxoedematosus, reticular erythematous mucinosis, scleroedema, mucinoses in thyroid disease, papular and nodular mucinosis in connective tissue diseases, self‐healing juvenile cutaneous mucinosis, cutaneous focal mucinosis, digital myxoid cyst; the latter include Pinkus follicular mucinosis and urticaria‐like follicular mucinosis. Associated disorders include paraproteinaemia (scleromyxoedema, scleroedema), diabetes mellitus (scleroedema), hyperthyroidism (pretibial myxoedema), hypothyroidism (generalized myxoedema) and lupus erythematosus, dermatomyositis or scleroderma (papular and nodular mucinosis in connective tissue diseases).
Keywords mucin, dermal mucinoses, follicular mucinosis, lichen myxoedematosus, scleromyxoedema, reticular erythematous mucinosis, scleroedema, localized and generalized myxoedema