Low viral load post-transplant lymphoproliferative disease localized within the tongue

Post-transplant lymphoproliferative disease (PTLD) can occur in different sites, such as lymph nodes, allograft, and central nervous system. We report a 6-year-old girl with end-stage renal disease secondary to hypoplastic-dysplastic kidneys, who received a kidney transplant. Thirty months post transplant, she developed PTLD in the tongue, an area of muscular tissue only. At that time her peripheral blood Epstein-Barr viral (EBV) load was only 40 copies/10⁵ lymphocytes, though the tumor was EB early RNA (EBER) positive. Immunosuppression was reduced with initial improvement in her symptoms. One month later, she returned with abdominal complaints and a contained cecal abscess. The excised cecal tissue revealed CD20 and EBER-positive lymphoid cells. At the same time, her peripheral blood EBV copy number rose to 400 copies/10⁵ lymphocytes. She was successfully treated for the progressive PTLD by complete cessation of immunosuppression and a modified reduced-dose chemotherapy protocol plus rituximab. Partial immunosuppression was eventually re-introduced with sirolimus and prednisone. She remains in remission 60 months post transplant, and 30 months post PTLD, with serum creatinine value maintained at 1.3 mg/dL. Unusual localization of PTLD to areas in non-lymphoid tissue without regional lymphoid involvement may result in misleading low peripheral blood EBV viral loads.