[Post-transplant lymphoproliferative disorder: a clinicopathologic study of 15 cases].

OBJECTIVE: To study the clinical and histopathologic features, diagnosis, pathogenesis and therapy of post-transplant lymphoproliferative disorders (PTLD). METHODS: The clinical and pathologic features of 15 cases of PTLD were retrospectively analyzed by light microscopy, immunohistochemistry and in-situ hybridization, according to the updated 2008 WHO classification of tumors of hematopoietic and lymphoid tissues. RESULTS: Amongst the 15 cases studied, 14 cases had received allogenic hematopoietic stem cell transplantation (AHSCT) and 1 case had received renal transplantation. There were altogether 12 males and 3 females. The male-to-female ratio was 4:1. The mean age was 30.4 years and the median age was 31 years (range from 9 to 60 years). PTLD developed 1.5 to 132 months after transplantation (median 13.0 months). The mean age of the 14 patients with AHSCT was 28.3 years (range from 9 to 45 years) and PTLD developed 1.5 to 19 months after transplantation (mean 4.5 months). Major clinical presentation included fever and lymphadenopathy. Twelve cases involved mainly lymph nodes and the remaining 3 cases involved tonsils, stomach and small intestine, respectively. The histologic types in 4 cases represented early lesions, including plasmacytic hyperplasia (n = 1) and infectious mononucleosis-like PTLD (n = 3). Seven cases were polymorphic PTLD, with 4 cases containing a predominance of large cells. Graft-versus-host disease was also seen in the case of small intestinal involvement. Four cases were monomorphic PTLD, 3 of which were diffuse large B-cell lymphoma, 1 was plasmablastic lymphoma and 1 was a mixture of monomorphic and polymorphic PTLD. Foci of necrosis were seen in 5 cases. The proliferating index of Ki-67 was high. The positive rate of EBV-encoded RNA in AHSCT was 92.9%. The duration of PTLD onset was shorter in EBV-positive cases (range from 1.5 to 7 months) than EBV-negative cases (range from 19 and 132 months). Some cases were treated by reduction of immunosuppression, antiviral agents or anti-CD20 monoclonal antibody Rituximab. The duration of follow-up in 14 patients ranged from 0 to 8 months. Five of the patients died of the disease. CONCLUSIONS: The diagnosis of PTLD relies on morphologic examination and immunohistochemistry. Most of them are of B-cell origin. EBV plays an important role in the pathogenesis of PTLD. The duration of disease onset is shorter in EBV-positive cases. PTLD in AHSCT cases occurs in younger age group, with shorter duration of onset, as compared to solid organ transplantation. The prognosis of PTLD is poor. The modalities of treatment include reduction of immunosuppression, antiviral agents or anti-CD20 monoclonal antibody Rituximab.