A medical book need not be pretty, but it must be necessary and informative. This monograph on the clinical and diagnostic pathology of graft-versus-host disease, provid ing detailed visual information on the histo morphological and immunohistological fea tures of GvHD, is intended to close a gap in the otherwise comprehensive medical literature on GvHD. B. Heymer Acknowledgements No one accumulates knowledge alone. lowe thanks to: Prof. G. R. F. Kruger, Houston, for introducing me to the histomorphological analysis of GvHD Prof. R. Arnold, Berlin, for many fruitful clinico pathological discussions Prof. K. H. Muller-Hermelink, Wurzburg, for expert advice in difficult histological differential diagnoses Prof. W. Mohr, Ulm, for continuous support and encouragement in moments of fatigue Last, but by no means least, Mrs. R. Endres-Klein, Ulm, without whom the preparation of this book would have been impossible In addition, I am grateful to the editorial staff at Springer, Heidelberg. B. Heymer Contents 1 Introduction. . . . . . . . . . . . . 1 1. 1 What Is Graft-Versus-Host Disease? 1 1. 2 Has the Pathology of GvHD Changed in the Past Decades? . . . . 1 1. 3 Why Write a Synopsis of the Clinical and Diagnostic Pathology of GvHO? 2 2 Occurrence of GvHD . . . . . . . . . 5 2. 1 GvHD After Allogeneic Bone Marrow Transplantation . . . . . . . . . . . . . 6 2. 2 GvHD After Allogeneic Peripheral Blood Stem Cell Transplantation 6 2. 3 Alternative Donors . . . . . . . . . . . . 7 2. 4 Umbilical Cord Blood . . . . . . . . . . 7 2. 5 GvHD After Materno-fetal Transfusion 8 2. 6 GvHD After Blood Transfusion . . . . . 9 2."