Eccrine porocarcinoma arising within an area of Bowen disease.

Summary Very little is known about the aetiology of eccrine porocarcinoma (EP), a rare malignant sweat-gland tumour. Most reported cases have arisen de novo, or from a benign eccrine poroma. We report an unusual case, in which eccrine porocarcinoma arose at the exact site of pre-existing Bowen disease (BD).

The pathophysiology of rosacea.

Rosacea is thought to be a common skin disorder in the general population, presenting with many different clinical features and unknown causes. Theories of pathogenesis have been extrapolated from clinical observation of factors, leading to a definition of the etiology of rosacea which was very limited until recently. A recent upsurge in translational research in rosacea has significantly advanced the insight into this disease. In this review the authors discuss the pathogenesis of this disease, which could be determined by the following factors: 1) exposure to UV radiation; 2) reactive oxygen species (including superoxide and hydroxyl radicals, hydrogen peroxide and singlet oxygen); 3) vascular hyperreactivity; 4) neuropeptides; 5) exacerbation of innate immune response; 6) microbes, in particular H. pylori and environmental aggressors, such as Demodex mite. Even if the recent investigations have significantly improved the understanding of its pathogenesis, the authors conclude that the histopathology of rosacea remains to be clarified according to subtype and age of development of individual lesions.