Hedblad MA, Nakatani T, Beitner H
DOI: 10.2340/0001555571108112

A male patient with clinically and histopathologically verified Darier's disease and a history of deterioration after sun exposure was irradiated on uninvolved skin with 25, 50 and 75 J/cm2 of UVA once a week for five weeks. He also received 3 and 5 times his individually established MED of UVB. Since no signs of keratosis follicularis were detected one week after the last irradiation, he was then exposed to 10 times his MED with UVB, whereupon clinically characteristic lesions of keratosis follicularis developed. One week after this exposure, biopsies were taken from the UV-induced lesions and processed for light and transmission electron microscopic investigation. Light microscopy revealed suprabasal lacunae, corps ronds and grains. In the electron microscope, gaps in the basal lamina beneath the suprabasal lacunae were also observed, through which cytoplasmic processes of lymphocyte- and fibroblast-like cells and basal keratinocytes protruded. Parts of keratinocytes with disruptive cell membranes were localized in the gaps of the basal lamina. Also, multiplication of the basal lamina was frequent.