Pediatric T-cell PTLD is very rare, with only 17 other cases previously described in the literature. We report two cases of T-PTLD with large abdominal nodal masses arising in children following SOT. The T-cell lineage was established based on immunohistochemistry and FCM analysis with T-cell monoclonality confirmed by FCM analysis of Vβ family usage and by PCR analysis of TCR-γ chain gene rearrangement. In contrast to most cases of B-lineage PTLD, these two T-PTLD cases were EBV-negative. This is consistent with data from the literature, with 42 of 69 (60%) T-PTLD cases being EBV-negative based on Southern blot hybridization with a fragment of the EBV genome or in-situ hybridization or EBV RNA. shows characteristics of the 14 cases of pediatric T-PTLD that arose following SOT, including the cases described herein.
Pediatric T-Cell PTLD After Solid Organ Transplant
While there is a general impression that T-PTLD is very difficult to cure, several recently reported cases, including those described in this report, demonstrate that these tumors can be very treatment responsive. This may be due to use of different chemotherapy regimens than those typically used to treat B-PTLD, such as the intensive ALL-type treatments we employed, and/or the use of different strategies for immunosuppression. Most T-PTLDs are not EBV-driven; thus, reduction of immunosuppression may not be effective as a sole treatment strategy, and may be less critical for management of T-PTLD than it is in EBV-driven B-PTLDs. However, the follow-up on several cases, including those we describe, is short and it will be important to gather information on a larger number of cases with longer follow-up to make definitive conclusions regarding the outcome of T-PTLD.
It is important to note that both of our pediatric T-PTLD cases exhibited a bimodal response to therapy, with initial eradication of the bulk nodal disease with regimens typically used to treat ALL, but persistence of low level clonal T-cells in marrow, CSF and lung (1 case). Case #1 showed prolonged disease control with modification of immunosuppression, including introduction of sirolimus, which may have anti-tumor activity [12
]. While we are cautious to make conclusions based on small patient numbers, different strategies of treatment may be needed in patients with T-PTLD than those that are often successful in treatment of B-lineage-PTLD. Multi-institutional trials are needed to define the optimal diagnostic evaluation and management strategy for T-PTLD.