The Pathology of Lung Allograft Rejection: A Concise Review

Lung transplantations in humans have been performed for almost 50 years. However, allograft rejection, non-rejection diseases such as harvest/reperfusion injury, infection, drug toxicity, post-transplant lymphoproliferative diseases, and recurrent disease are still significant complications. Although the clinical impression might suggest the possibility of any of these conditions, tissue diagnosis is usually necessary to establish a definitive diagnosis. This article mainly focuses on reviewing the morphological features of lung allograft rejection and its grading according to the revised 2007 ISHLT consensus classification of allograft rejection. Acute and chronic alloreactive injuries affect both the vasculature and the airways. Currently, the guidelines of the 2007 ISHLT consensus conference are used for the histolopathologic assessment of rejection. Although antibody mediated rejection is recognized in heart and kidney transplants, at present, there is no consensus about its diagnosis in transplanted lungs. Mimickers of rejection and post-transplant diseases will also be discussed. The collaboration between the transplant clinician and pathologist cannot be overemphasized to establish an optimal treatment for the individual patient following lung transplantation.