Basement membranes in ultraviolet light-induced skin lesions and tumors.

Basement membrane changes in human skin exposed to UV irradiation were studied by light and electron microscopy and antibodies to human collagen IV and laminin were compared to similar lesions in non-sun-exposed areas. A distinct basement membrane was seen in cases of epidermal solar keratosis, even with marked dysplasia and Bowenoid type lesions, and also around most of squamous cell carcinomas which showed basement membrane irregularities, thickening and reduplication. The invading edges of the squamous cell carcinomas with inflammatory infiltrates were devoid of laminin and collagen. Basement membrane disruption was also observed in lichen planus-type solar keratosis with severe inflammation, but with no evidence of malignancy. Alterations in basement membrane structure and location were associated with cutaneous morphological abnormalities not due to UV irradiation as such.