Classification and epidemiology of scleroderma.

Scleroderma is classified as two separate but related entities, a localized form and a systemic form. The classification scheme for morphea presented here is that of Peterson et al, which divides morphea into five categories: plaque, generalized, bullous, linear, and deep. Using this system, these authors estimated the incidence rate of localized scleroderma to be 27 new cases per million population per year. Overall survival was similar to that of the general population. There was a preponderance of female cases (approximately 3:1) for all forms of morphea except for linear scleroderma, which had an even sex distribution. Systemic scleroderma is divided into limited and diffuse disease based on the extent of skin involvement. Recent estimates have placed the incidence rate of systemic sclerosis in the United States at 19 new cases per million adults per year, with an overall prevalence of 240/million adults. The female-to-male ratio is approximately 5:1. The prevalence of scleroderma varies by geographic region and ethnic background and is higher in the United States than in Europe or Japan. Although systemic sclerosis survival has improved over the past two decades, with 5-year survival over 80%, long-term survival is significantly lower than expected, and morbidity is considerable.