[A combination of psoriasis vulgaris and nevus cell nevus--clinical, histopathologic and histochemical findings].

In a study on 76 patients suffering from psoriasis, we found melanocytic nevi (MCN) within psoriatic lesions in 7%, and in perilesional areas of about 2 cm in 13% of the patients. Under magnification (operating microscope), we failed to detect any signs of psoriasis in both the epidermis covering the MCN and the adjacent epidermis. Histopathologically, 6 out of 7 MCN examined did not show any psoriatic alterations of the epidermis, and in all the 7 cases, the adjacent epidermis was free of psoriasis. Using unfixed frozen sections in histochemistry, we studied the lectin binding of FITC-labeled ConA and UEA I in 5 MCN. The epidermal reaction was comparable to that of psoriatic lesions. In contrast to psoriatic lesions, there was no staining of the spinous layer with a polyclonal antiserum against calmodulin, but only the staining of basal cells as in non-lesional psoriasis. We discuss possible 'protective' factors against psoriasis.