HOMOLINEAR EPIDERMAL NEVUS AND BLASCHKITI S IN AN ADULT

Introduction. Many inherited skin diseases and nevus malformations are distributed according to the Blaschko's lines. Some inflammatory skin diseases are also distributed according to these lines. Observation. In 1989 a 49-year-old woman presented with an epidermal nevus affectin g the left hand and leg from the infancy. In 1994, inflammatory, linea r papules occurred on the left leg, obscuring and continuing the previ ous lesions, on the left thigh and on the left clavicular region. On l ight microscopy, spongiosis of the epidermis and an infiltrate of lymp hocytes and histiocytes in the superficial dermis were shown. Subintra nt crops of new inflammatory lesions occur-red for a period of two pea rs, whereas the nevus lesions of the left hand persisted unchanged. Th ese findings led to the final diagnosis of blaschkitis associated to e pidermal nevus on the same Blaschko's lines. Discussion. The distribut ion of a skin disease according to the Blaschko's lines underlines the presence in the affected skin of a mutant clone, with a different gen etic material as compared with the normal skin. An early mutation givi ng raise to a mutant clone and affecting the left hemibody could be hy pothesized in our case. The mutation probably involved a pleiotropic g ene. The latter initially was responsible for thickening of the skin. Moreover, the mutation was also responsible for a particular proneness towards an exogenous factors, able to induce a persistent inflammator y skin eruption following the same lines.