ABSTRACT
Many diseases that are affected by exposure to ultraviolet radiation (UVR) are not actually caused by UVR. Many inflammatory diseases improve or clear following UVR exposure. This chapter will encompass diseases not primarily caused by UVR but usually or occasionally exacerbated by it. Aggravation or worsening of diseases by UVR may occur for a variety of different mechanisms. The disease may be an inflammatory disease, and in some individuals, UV exposure may just add to inflammation. The disease may be complicated by coincidence with a sun-induced inflammatory disorder and appear to be aggravated by UV exposure. For the disease to be truly photoaggravated, it should show exacerbation with primary lesions of the disease itself. In this situation, the disorder may actually be induced by UV exposure. A moderate number of dermatoses that are not actually induced by UVR may be worsened by it (Table 9.1). The immunological activity involved in their disease mechanism may be increased by UVR, or (more rarely) any already-present inflammation can be increased by UVR.
