"Post-transplant lymphoproliferative disorder (PTLD), also known as post-transplant lymphoproliferation disorder, represents a variety of conditions ranging from lymphoid hyperplasia to malignancy, included in the WHO classification of haematolymphoid tumours under "lymphoid proliferations and lymphomas associated with immune deficiency and dysregulation." It can be a life-threatening fulminant disorder."
"Epstein-Barr virus seronegativity at the time of transplantation (which may explain why the incidence of PTLD is higher in children)"
"reactive nodal enlargement, e.g. from URTI"