Hippokratia 1999, 3(1): 10 - 16
The problem of differential diagnosis of lung allograft dysfunction is difficult, since pulmonary acute rejection episodes and opportunistic infections have a higher rate frequency than in other allografts. The histopathological lesion of acute pulmonary rejection is characterized by perivascular mononuclear cell infiltrates in the interstitium and bronchiolar inflammation. The grading system of lung rejection is based on histological parameters. An acute rejection episode is graded according to the nature and extent of mononuclear cell infiltrates. Perivascular and peribronchiolar mononuclear cell infiltrates are the common feature in pulmonary infections.
Special histochemical stains and molecular techniques facilitate the diagnosis. Chronic pulmonary rejection is characterized by obliterative bronchiolitis and chronic vascular rejection. Obliterative bronchiolitis has many other causes such as drugs, toxins and infections, so biopsy assessment is crucial for diagnosis and therapy.