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.