Comprehensive overview on new aspects of evolving concepts in the pathology arising in patients with secondary immunosuppression This special issue of Pathobiology on 'Immunosuppression-Associated Pathology' is focusing on pathologies evolving from secondary immunodeficiency states induced by immune-modulatory drug therapy in the context of auto-immune diseases and in the prevention of transplant rejection. In an introductory article, biological concepts of immune-modulatory drugs currently in use or appearing on the market in the near future are explained. This is essential in understanding the indications, limitations and side effects of such drug administration. Furthermore, this publication focusses on rarely involved patient's age groups such as pediatric patients as well as on particular anatomical sites such as the central nervous system and the skin. Novelties herein are EBV-associated smooth- muscle tumors in pediatric patients with congenital or acquired immunodeficiency states as well as mycophenolate induced apoptotic colonopathies. Immunosuppression Associated Pathology is of special interest to general and specialized pathologists as well as clinicians treating patients with immunomodulatory and immunsuppressive drugs and pharmaco-scientists.