Psoriatic lesions are relatively frequent in patients with chronic liver disease. Furthermore, therapy with interferons tends to exacerbate the symptoms. The pathogenesis of psoriatic lesions is unclear. An important question is whether such lesions may be linked to the underlying chronic liver disease in these patients, or whether they are incidental manifestations of psoriasis vulgaris. We collected biopsy specimens from involved and uninvolved skin areas of chronic liver disease patients with psoriatic manifestations, as well as from psoriasis vulgaris patients, and investigated the patterns of integrin adhesion receptors by means of immunohistochemical methods. Integrin expression is known to be characteristically altered in psoriasis vulgaris. We found some of these changes in chronic liver disease psoriatic lesions-namely pericellular redistribution and suprabasal expression of the basement membrane receptor alpha 6 beta 4 and of the intercellular integrins alpha 2 beta 1 and alpha 3 beta 1. However, psoriasis vulgaris causes two other typical changes: One is the induction of the prototype fibronectin receptor alpha 5 beta 1, and the other is the alteration of integrin expression in areas of the epidermis that are macroscopically normal. These two changes were not found in chronic liver disease psoriasis biopsy specimens in 14 patients investigated. Thus integrin expression may be useful in differentiating chronic liver disease psoriatic lesions from psoriasis vulgaris lesions. Even though the two types of lesions are indistinguishable on inspection or by their histological features, they may be caused by distinct pathogenetic mechanisms. It remains to be seen whether the underlying chronic liver disease has a role, albeit indirect, in such mechanisms.