Classical Hodgkin lymphoma type post-transplant lymphoproliferative disorder in a kidney transplant recipient: a diagnostic pitfall.

We report a case of classical Hodgkin lymphoma type post-transplant lymphoproliferative disorder (HL-PTLD) after kidney transplantation to highlight the difficulty of distinguishing this disorder from Hodgkin lymphoma-like PTLD (HL-like PTLD). Through this case report and literature review, we seek to clarify definitive pathologic features to differentiate these two conditions. A 38-year-old male kidney transplant recipient who had been receiving immunosuppressants was admitted to our hospital with unidentified high fever. Computed tomography images and blood tests indicated a lymphoproliferative disorder. Abdominal lymph node biopsy was performed, and microscopic examination revealed the presence of many large atypical cells in a background of dense T cell accumulation. The large, atypical cells were positive for Epstein-Barr Virus (EBV)-encoded small RNAs (EBER) in situ hybridization, EBV-LMP1, CD30 and PAX5, but negative for CD15, CD20 and CD45. Except for CD15-negativity, this immunohistochemical pattern was consistent with that of classical Hodgkin lymphoma. By close examination of the above immunoreactivities and the patient's subsequent chemosensitive clinical course, we finally made a diagnosis of HL-PTLD.