[Graft-versus-Host Disease (GvHD) - an update : Part 1: Pathophysiology, clinical features and classification of GvHD].

GvHD remains associated with significant morbidity and mortality despite new techniques for allogeneic stem cell transplantation (SCT), such as optimized conditioning regimens. Within the past ten years, the incidence of acute GvHD has remained unchanged and the incidence of chronic GvHD has even increased. The traditional classification of GvHD according to the time of clinical manifestation is now out-dated. Acute GvHD symptoms may even occur after 100 days; vice versa, primary chronic GvHD may already be observed one month after stem cell transplantation. The current classification introduced by the National Institutes of Health includes classic acute GvHD (up to 100 days), late-onset acute GvHD (after 100 days), as well as an overlap syndrome showing features of acute and chronic GvHD and classic chronic GvHD without any time limit. Diagnosis of GvHD of the skin remains difficult because of histological similarities to drug eruptions and viral exanthems. In this first part of the article the pathophysiology, classification, skin manifestations of acute and chronic GvHD and the histopathology will be presented. In a second part the prognosis, prophylaxis and therapy of GvHD will be discussed.