Post-transplant lymphoproliferative disorder resembling Wilms tumor. Diagnostic dilemma: Renal biopsy or nephrectomy?

Post-transplant lymphoproliferative disorder is a life-threatening neoplasm that can occur after orthotopic liver transplant. We report a 14-month-old female status-post OLT with an atypical presentation of PTLD as a solitary renal mass. At eight-wk post-transplant, she presented with elevated transaminases, CMV counts (73 000 copies/mL), and EBV counts (35 000 copies/mL). CT scan revealed a solid heterogeneously enhancing right renal mass measuring 2.6 × 2.4 × 3.3 cm. The radiological diagnosis was Wilms tumor, although PTLD could not be excluded. Complete resection of a Wilms tumor is potentially curative. A needle biopsy would upstage the malignancy and result in radiochemotherapy that is deleterious to a liver graft. The mass was not amenable to partial nephrectomy. A total nephrectomy, given life-long nephrotoxic immunosuppressants, was an unfavorable option. Thus, needle biopsy was performed. Histology confirmed monoclonal, EBV-associated PTLD and diffuse large B-cell lymphoma. Her therapy included immunosuppression reduction, cyclophosphamide, steroids, and anti-CD20 monoclonal antibody. Concomitantly, she received Cytogam and gancyclovir. Complete remission was achieved three months after chemotherapy. This case illustrates that young age, CMV infection, and EBV infection are strong risk factors for PTLD. With such risk factors present, any mass or lesion in a solid organ transplant patient should be considered PTLD until proven otherwise.