We report the case of an eight-yr-old child with early onset PTLD half a year after renal transplantation. The patient developed gastrointestinal pain and bowel biopsies revealed imposing lymphoid infiltrates with small spots of lymphoid blasts in the colonic mucosa. These findings were interpreted as transplantation associated B-cell stimulation. However, the persistent severe abdominal pain led to the resection of a jejunal segment. Here, gut wall perforation caused by a tumor mass was seen. Histologically, a blastic lymphoid cell proliferation of B-cell origin with high proliferation rate and EBV association could be demonstrated. IgH rearrangement analysis and in situ hybridization revealed an oligoclonal B-cell pattern. Reduction of immunosuppression and treatment with rituximab led to lymphoma remission and conversion of EBV serology four wk later. The report presented herein demonstrates the evolution of an oligoclonal lymphoproliferation with direct disease progression towards EBV associated PTLD by analyzing different stages of the disease.