Acquired blaschkolinear dermatoses

Congenital and/or nevoid skin disorders following the lines of Blaschko may have a delayed onset after birth. They have to be differentiated from acqu ired dermatoses exhibiting the same Linear pattern. In common dermatoses, s uch as psoriasis or lichen planus, lesions in a blaschkolinear distribution most often occur together with scattered lesions, but occasionally they ma y be isolated. Less common self-limited dermatoses such as Lichen striatus and adult blaschkitis always present in a blaschkolinear fashion. In these diseases, or some other conditions occasionally distributed along these lin es (chronic graft versus host reaction, fixed drug eruption, lupus erythema tosus, atopic dermatitis, etc.), the cause of the disease may lead to the u nmasking of tolerance to an abnormal keratinocyte clone that remained hidde n in these lines. In addition to epithelial cells, other cells may be invol ved in the occurrence of acquired blaschkolinear dermatoses. In linear atro phoderma and linear fibromatosis, the histogenesis seems to involve hypothe tic dermal clones. The extension of an acquired dermatosis on a preexisting linear nevoid disorder is an argument in favor of an early embryonic somat ic mutation of a skin cell line. (C) 1999 Wiley-Liss, Inc.