Squamous-cell carcinoma in situ.

We present a 30-year-old woman with atopic dermatitis and ichthyosis vulgaris and a one-year history of an erythematous, scaly plaque on the dorsal surface of her right hand, which developed three years after an accidental exposure to prolonged ultraviolet C (UVC) radiation in a laboratory accident. The plaque, which was initially treated as eczematous dermatitis, was eventually identified histopathologically as squamous-cell carcinoma in situ. Although causation is not definitive, this case is the first to describe development of non-melanoma skin cancer (NMSC) in an area of skin known to be acutely exposed to UVC radiation. As UVC radiation becomes a more frequently used anti-microbial technology, UVC radiation may become a more commonly identified risk factor in the development of NMSC.