Atypical epidermolysis bullosa simplex with a missense keratin 14 mutation p.Arg125Cys.

Epidermolysis bullosa (EB) is a group of hereditary autosomal dominant bullous diseases. EB is divided into four major phenotypes: intraepidermal EB (or EB simplex), junctional EB, dermolytic EB and mixed EB (Kindler syndrome). EB simplex is further divided into three subtypes: localized EB simplex, Dowling-Meara EB simplex and other generalized EB simplex. We report a 28-year-old man with EB simplex with a missense keratin 14 mutation p.Arg125Cys associated with clumping of keratin filaments and acantholysis in mainly the spinous cells and basal cells. Immunohistochemistry revealed that the broader expression of keratin 5 and 14 was observed in the epidermis, while the expression of keratin 1/10 was quite normal. Dysregulated expression of keratin 5/14 may hinder some functions or roles of keratin 1/10, namely filament assembly of keratin 1/10 in spinous cell integrity, although the expression of keratin 1/10 was not affected and this has not been demonstrated before.