Very late relapse of PTLD 10 yr after allogeneic HSCT and nine yr after stopping immunosuppressive therapy.

We present a very late onset relapse of PTLD 10 yr after allogeneic HSCT in a patient in third remission for ALL, nine yr after the first episode of PTLD. The recipient was conditioned with fractionated TBI 12 Gy, cyclophosphamide, and horse ATG. The first episode of PTLD with a large retroperitoneal tumor occurred one yr after transplantation; a residual tumor infiltrating spleen and colon was resected one yr later. Due to continual pathological signals in liver and lungs, persistent fever, and an M-component in peripheral blood, a new course of four rituximab doses was given, after which the fever settled, the PET scan normalized, and the M-component disappeared. Without any ongoing immunosuppressive therapy, PTLD relapsed nine yr later with large intra-abdominal lymph node masses causing ureteric obstruction with bilateral hydronephrosis. Pathological features were identical to the primary PTLD tumor: EBV related, of donor origin, positive for CD138 and CD79 alpha, but negative for CD20 and CD19. The transcription factor PAX5 was negative but BOB1 and OCT2 were positive, consistent with plasmablastic lymphoma. The relapse was successfully treated with a combination of low dose chemotherapy and rituximab. Five yr after end of treatment, the girl has moderately reduced renal function but otherwise remains well without evidence of disease.