Polymorphic PTLD may be either polyclonal or monoclonal and is characterized by the destruction of underlying lymphoid architecture, necrosis, and nuclear atypia. In monomorphic PTLD, most cases arise from B cells, similar to non-Hodgkin's lymphoma in immunocompetent hosts. The B cell neoplasms may include diffuse large B cell lymphoma, Burkitt's lymphoma, plasma cell myeloma, and plasmacytoma- like lesion, while T cell neoplasms may include peripheral T cell lymphoma and hepatosplenic T cell lymphoma. The two most commonly found histopathologies of PTLD after lung transplantation have been monomorphic diffuse large B cell lymphoma and polymorphic B cell lymphoma