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Both auricles of 21 domestic rabbits were painted with dimethylbenz-anthracene (DMBA). Eleven animals of this group were additionally fed aromatic retinoid (AR) by an esophageal tube. Two control animals were not treated at all. Eight or 9 weeks after the beginning of the study six of the seven remaining animals, which had only been painted with DMBA, developed a total of 25 keratoacanthoma-like tumors (KA). On the other hand, none of the seven animals left, which were painted with DMBA and fed AR showed any tumor by this time. The systemic effect of AR was studied in biopsies from the snout and the back. The epidermis of the snout showed 'mucous mataplasia' by histochemical and electron-microscopic criteria, whereas the epidermis of the back was not significantly altered. The production of intra- and extracellular lamellated material indicated an additional effect of AR on epidermal lipid metabolism. The effect of AR in the prevention of DMBA-induced tumors was characterized by 'mucoid cytolysis' and karyolysis. [ABSTRACT FROM AUTHOR]

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The phospholipid pattern of the involved and the uninvolved epidermis from 48 psoriatic patients and of the normal epidermis from 23 healthy controls was determined by thin-layer chromatography. A higher amount of total phospholipids was found only in the involved psoriatic epidermis, whereas significant alterations in the phospholipid pattern were observed in the psoriatic lesion and in the lesion-free epidermis. Namely, the decrease of phosphatidylserine and the increase of phosphatidylinositol were identically present in both the involved and the uninvolved psoriatic epidermis. It seems likely that these alterations in the phospholipid pattern in psoriasis may be related to subclinical alterations of the epidermis in this disease.

To investigate the turnover of complete junctional membrane areas ("domain turnover"), psoriatic epidermis, keratoacanthoma, and squamous cell carcinoma were studied with an electron microscope and compared with the normal epidermis. Three types of domain turnover of junctions were observed. First, the uptake of intact intercellular junctions, which occurred as complete or incomplete annular junctions in the cytoplasm. Mainly gap junctions were involved. Second, the formation of autojunctions bridging an infolding at the surface of a cell, which is then incorporated and occurs partly with an attached saccule in the cytoplasm. This type was confined to desmosomes. Finally, the loss of intercellular desmosomes into the intercellular space was observed. Proliferating epidermis was associated with an increased domain turnover of gap junctional membrane areas. Domain turnover of desmosomes prevailed in tumors.

Three cell surface parameters of epidermal cells have been studied by immunofluorescence, pemphigus antigens, concanavalin-A binding sugars, and beta 2 microglobulin. Biopsy specimens were taken from a total of 59 patients with psoriasis, seborrheic and solar keratosis, squamous cell carcinoma, and basal cell epithelioma. We found a loss of demonstrability of all parameters in dedifferentiated tumors or tumor areas in squamous cell carcinoma, premonitory changes in solar keratosis, and no changes in seborrheic keratosis. In the psoriatic epidermis a granular redistribution of the cell surface parameters was occasionally observed in circumscribed areas of the epidermis. A selective loss of the demonstrability of beta 2 microglobulin was the prominent feature in basal cell epithelioma. Our findings demonstrate that the alterations of the cell surface differ in malignant and premalignant skin tumors, in basal cell epithelioma, and in benign psoriatic hyperplasia.