J Eur Acad Dermatol Venereol. 2009 Sep 8; Lazaridou E, Apalla Z, Sotiraki S, Ziakas NG, Fotiadou C, Ioannides DAbstract Background Numerous factors have been implicated in the pathogenesis of rosacea, which remains obscure. Objectives To examine the epidemiological characteristics of rosacea patients, the histopathological alterations, the prevalence of gastric Helicobacter pylori infection and the role of ultraviolet radiation, to detect the presence of Demodex folliculorum on affected skin and to elucidate the immunological nature of this disorder. Methods The study included 100 patients with rosacea. Each patient was assessed with a clinical, haematological, biochemical and histological examination; serology test for the detection of antibodies against H. pylori; direct immunofluorescence on perilesional, sun exposed skin and indirect immunofluorescence with monkey oesophagus as a substrate; antinuclear antibody titre and a skin surface biopsy to search for Demodex folliculorum. Re...