disorders. Prevalence rates vary between 14 and 50 per 100,000 population (Hochberg 1997). Cutaneous LE (CLE) presumably occurs two to three times more frequently than SLE. However, exact population-based epidemiologic data are not available. In selected groups of patients with LE cared for in dermatology departments, the prevalence of patients with chronic discoid LE (DLE) varies between 42% and 72% (Kind and Goerz 1987, Tebbe and Orfanos 1987), and subacute cutaneous LE (SCLE) is found in 7%–32% of the entire collective (Molad 1987, Sontheimer et al. 1979, Tebbe and Orfanos 1987). The prognosis of SLE depends on the severity and extent of visceral involvement. Most fatalities among patients with SLE are attributable to active disease, especially to renal and central nervous system involvement, and to various infections. However, the 10-year survival rate today exceeds 80% owing to treatment with oral corticosteroids and potent immunosuppressive drugs (Drenkard and Alarcon-Segovia 2000, Gladman 1996, Swaak 1989). In general, the prognosis of CLE is regarded as more favorable than that of SLE, although prospective studies in large groups are rare. Classic variants of specific CLE lesions are DLE and SCLE. Other typical CLE subsets, such as LE profundus/panniculitis, LE tumidus, urticaria vasculitis, hypertrophic LE, and bullous LE, are rather rare variants. Butterfly rash and macular exanthema are characteristic skin lesions of SLE rarely found in patients with CLE. DLE and SCLE may appear at any age, but the most common age at onset is 20–40 years in females and males, with a female predominance of 3:1 in DLE and 3:1 to 6:1 in SCLE. Nonspecific LE skin lesions such as generalized or acrolocalized vasculitis (4%–30%), livedo reticularis (22%–35%), and alopecia (38%–78%) are frequently seen in patients with CLE (Beutner et al. 1991, Callen 1985, 1986, Molad 1987, Moschella 1989, Sontheimer 1979, Tebbe and Orfanos 1992). DLE and SCLE are generally regarded as disease variants with a better prognosis than that of SLE, and severe courses of cutaneous variants with a lethal outcome are rare. However, if mild signs of systemic manifestations, such as proteinuria and arthralgia, were registered in CLE, 14%–27% of patients with DLE and 67%–70% of patients with SCLE had extracutaneous involvement (Sontheimer 1989, Tebbe et al. 1997, Watanabe and Tsuchida 1995). It seems that ca. 5%–10% of patients with DLE will experience transition to SLE during long-term disease (Healy et al. 1995, Le Bozec et al. 1994, Millard and Rowell 1979, Rowell 1984, Schiodt 1984). In most cases, transition to SLE requires more than 5 years (Healy et al. 1995, Le Bozec et al. 1994). However, severe life-threatening manCHAPTER 14