[Blaschkitis in adults].

Many dermatoses may exhibit lesions distributed in a linear fashion: the linearity may be related to anatomical structures (blood or lymph vessels, nerves), to mechanical factors (urticarial dermographism, striae distensae cutis, frictional melanosis) or to some other provocative injuries being themselves linear (for instance Köbner's phenomenon). Some congenital or acquired dermatoses, either inherited or sporadic, have a linear distribution following the embryonic lines described in 1901 by A. Blaschko. Most of them are nevoid skin lesions present at birth or having a later onset: epidermal nevi (naevus unius lateris, linear porokeratosis), adnexal nevi (linear sebaceous nevus, linear basal cell nevus), pigmented lesions (systematized linear achromic nevus) or intricated nevi of the connective tissue (angio-lipomatous nevus). More seldom, genodermatoses related to a X-chromosomal mosaicism, occurring in females only, exhibit also a linear arrangement of their skin symptoms following Blaschko's lines: incontinentia pigmenti, focal dermal hypoplasia, etc. There are also very common inflammatory skin diseases, without any genetical background, which sometimes present as linear dermatoses. Their pattern according to Blaschko's lines is obvious in some cases: linear lichen planus, linear lichen nitidus, linear scleroderma, linear (zosteriform) vitiligo, linear fixed drug eruption, linear chronic lupus erythematosus. In some other conditions, the arrangement following these lines is probable (lichen striatus, linear eczema) or dubious (unilateral nevoid telangiectasias). This case report concerns a 38-year old man exhibiting relapsing inflammatory linear lesions of Blaschko's lines on the chest, back and upper limbs. Histological examination showed a non specific spongiotic dermatitis with rare necrotic keratinocytes and exocytosis of lymphocytes in the stratum spinosum.(ABSTRACT TRUNCATED AT 250 WORDS)