The evolution of abnormal reactions to ultraviolet radiation (UVR) was studied in two subjects. Both of these individuals developed abnormal reactions to UVR in the UVA (320 to 400 nm) and the UVB (290 to 320 nm) ranges. The clinical and histopathologic development of these reactions in the UVB range were studied over the course of 24 hours. There was a mild perivascular infiltrate in the upper dermis leading to a severe angiitic response and marked dermal edema at four hours after ultraviolet irradiation. At 24 hours there were, in addition to a marked angiitis, epidermal changes consisting of spongiosis, exocytosis, and liquefaction degeneration of the basal layer. It is this light test reaction at 24 hours which mimics the clinical disease state in the individual so tested. A possible pathogenetic mechanism is suggested.
Stern WK. Evolution of an Abnormal Light Test Reaction. Arch Dermatol. 1971;103(2):154-157. doi:10.1001/archderm.1971.04000140040007