Common Causes of Diffuse Alveolar Damage in the Pulmonary Allograft

Lung transplantation may offer longer survival and improved quality of life to patients with end-stage lung disease. Common indications for single lung transplantation include chronic obstructive pulmonary disease, idiopathic pulmonary fibrosis­, and α1-antitrypsin deficiency emphysema. Bilateral lung transplantation is the norm for cystic fibrosis, but the proportion of bilateral (double) lung transplantation procedures has been rising for other major indications as well. Benchmark survival rates for adult lung transplant recipients are 89% at 3 months, 80% at 1 year, 65% at 3 years, 54% at 5 years, and 31% at 10 years after transplantation. Complications of lung transplantation may be related to (1) the operation itself (primary graft dysfunction, anastomotic complications), (2) the host’s immunologic response to the allograft (rejection), and (3) the immunosuppressive therapy used to prevent rejection (infection, posttransplantation lymphoproliferative disorder [PTLD]). Other complications, such as organizing pneumonia and recurrence of the original disease, may also occur. Posttransplantation transbronchial biopsy may be performed for a specific clinical indication or for surveillance of acute rejection. The histopathologic findings most commonly encountered in a posttransplantation transbronchial biopsy include acute rejection, cytomegalovirus infection, airway-centered inflammation, pneumonia, bronchiolitis obliterans, harvest injury, invasive aspergillosis, and PTLD.