Mucinosis and Disorders of Collagen and Elastic Fibers

Cutaneous mucinoses are a heterogeneous group of disorders having as a common denominator the deposition of an excess of mucin (acid glycosaminoglycans, mostly hyaluronic acid) in the dermis or in the hair follicles. They are divided into primary and secondary forms. Primary cutaneous mucinoses are characterized by specific clinical lesions in which mucin deposition is the distinctive histological sign, while in secondary mucinoses, mucin deposition is simply an accessory histological sign. Disorders of collagen and elastic fibers are divided into hereditary and acquired forms. Both forms can be further divided into those diseases characterized by an increase and those by a decrease in collagen and elastic tissue. A peculiar variant of disorders of dermal connective tissue includes the primary perforating dermatoses.