Morphologic Evolution in Post-Transplant Lymphoproliferative Disorders (PTLD): A Clinicopathologic Case Series

Post-transplant lymphoproliferative disorders (PTLDs) are classified as early PTLDs (E-PTLD), polymorphic PTLDs (P-PTLD), monomorphic PTLDs (M-PTLD) and classical Hodgkin's Lymphoma PTLD (HL). These entities are felt to represent a disease continuum, with a precursor-product relationship, though they are morphologically and clinically distinct. However, this process remains poorly understood, and limited evidence exists to support this hypothesis. We report a series of nine cases extracted from a PTLD database, including both pediatric and adult solid organ transplant recipients, with recurrent disease episodes that evince an apparent evolution in their morphologic categorization between episodes. All patients identified were high risk for PTLD, with multiple identifiable predisposing factors. Presentations varied from isolated lymphadenopathy, to gastrointestinal involvement to pulmonary involvement. Four of the patients were deceased at the time of acquisition, though only one directly from PTLD. Eight of the nine identified patients developed E or P-PTLD lesions that preceded a subsequent M-PTLD or HL lesion at a similar tissue site. Two of the cases had metachronous P and M-PTLD lesions. The six M-PTLD subtypes were variable, including DLBCL, Burkitt, T-cell, and extramedullary plasmacytoma, in addition to the three cases of classical Hodgkin's lymphoma. These cases suggest that E and P-PTLD may act as common precursor lesions to the development of both the M-PTLD variants and HL type lesions, and that the PTLD classification schema represents different stages of a common underlying pathology.