EBV Negative NK/T-Cell PTLD of the Distal Ileum in a Renal Transplant Recipient

Abstract

Post-transplant lymphoproliferative disorder (PTLD) represents a spectrum of Epstein-Barr virusrelated (EBV) clinical diseases from a benign mononucleosis-like illness to a fulminant non-Hodgkin's lymphoma. We describe a case of a PTLD in a patient with renal transplant. 21 yo male with congenital nephrotic syndrome and living donor renal transplant was diagnosed with polymorphic PTLD 2 years ago. He presented with fatigue, anemia, back pain and recurrent sinus infections. Staging CT scans revealed cervical and mesenteric lymphadenopathy. Patient underwent excisional cervical lymph node biopsy with pathology positive for polyclonal PTLD. His EBV viral load was above 100,000. Patient's immunosuppression was decreased and he received 6 cycles of chemotherapy with cyclophosphamide, rituximab and prednisone. Post-treatment re-staging scans showed no evidence of the disease.Three months later patient presented with a new onset of back pain and signs of bowel obstruction. Images showed a soft tissue density in right mid-abdomen. He was found to have a 4cm distal ileum mass with caecal intussusception and underwent a resection with an end-end anastomosis. Pathology report was consistent with monomorphic PTLD: DLBCL type.During recovery period he presented with weight loss, back pain, and an enlarged lymph node in anterior chest. Restaging PET/CT scan revealed diffuse hypermetabolic activity in multiple lesions of the neck, chest, abdomen, pelvis and bones. Serum EBV viral load was negative. Previous surgical specimen was reviewed and final diagnosis changed to EBV negative NK/T-cell PTLD. Patient was started on systemic chemotherapy regimen with SMILE (dexamethasone, methotrexate, ifosfamide, l-aspariginase, etoposide) and tolerated treatment well.PTLD is a rare complication after stem cell or solid organ transplantation and is related to unbalance between EBV-infected B lymphocytes and specific T cells of response. Revised WHO classification includes early lesions, classic HL-type, polymorphic and monomorphic PTLD. The majority of monomorphic PTLD are of B-cell origin: diffuse large B-cell lymphoma (DLBCL) or Burkitt lymphoma. 5% of cases are T-cell types and around 1% represent the NK/T-cell type.The incidence of PTLD following renal transplant is approximately 1% at 10 years, with greater than 80% of cases occurring within the first year following transplant.Our patient had unusual presentation: he had EBV negative monomorphic PTLD NK/T-cell lymphoma - the type of disease which is exquisitely rare. He also had a long time interval before malignant transformation and an unusual site of involvement.Clinicians need to have a high level of suspicion for malignancy in stem cell and solid organ transplant recipients. Rarely patient's symptoms of intussusception might be related to NK/T cell lymphoma.