Cytogenetic analysis of B-cell posttransplant lymphoproliferations validates the World Health Organization classification and suggests inclusion of florid follicular hyperplasia as a precursor lesion

Cytogenetic abnormalities in B-cell posttransplant lymphoproliferative disorders (PTLD) have not been well characterized. We thus performed cytogenetic analysis of 28 cases of B-cell PTLD, 1 infectious mononucleosis (IM)-like lesion, 9 polymorphic PTLD, 17 monomorphic PTLD, and 1 classical Hodgkin lymphoma (HL), and correlated the karyotypic findings with the phenotype, Epstein-Barr virus infection status, and clinical outcome. Karyotypes of 19 cases of posttransplant florid follicular hyperplasia (FFH) were also analyzed. Informative karyotypes were obtained in 20 (71.4%) of 28 PTLDs and 18 (94.7%) of 19 FFHs. Clonal karyotypic abnormalities were detected in 13 (65%) of 20 PTLDs, including 9 (75%) of 12 monomorphic PTLDs, 2 (33.3%) of 6 polymorphic PTLDs, 1 IM-like lesion, and 1 HL, and 2 (11.1%) of 18 FFHs. Recurrent chromosome breaks at 1q11-21 (n = 6, including 1 FFH), 14q32 (n = 3, including 1 FFH), 16p13 (n = 3), 11q23-24 (n = 2), and 8q24 (c-MYC) (n = 2); gains of chromosome 7 (n = 4), X (n = 3), 2 (n = 3), 12 (n = 2); and loss of chromosome 22 (n = 2, including 1 IM-like lesion) were identified. The presence of cytogenetic abnormalities did not correlate with PTLD phenotype, Epstein-Barr virus infection, or clinical outcome. We describe novel karyotypic aberrations in PTLD and report clonal cytogenetic abnormalities in posttransplant FFH and an IM-like lesion for the first time. Our findings provide validation of the current World Health Organization classification of PTLD and also suggest incorporation of FFH as the earliest recognizable precursor of PTLD.     

Post-transplant lymphoproliferative disorder subtypes correlate with different recurring chromosomal abnormalities

Although cytogenetic analysis advanced the understanding of the pathogenesis of primary non-Hodgkin lymphoma and led to improved clinical management, there have been no large cytogenetic studies of post-transplant lymphoproliferative disorder (PTLD). We examined the karyotypes of 36 PTLD cases and correlated them with clinical, laboratory, and pathologic findings. The cases included 2 early lesions, 13 polymorphic PTLDs, and 21 monomorphic PTLDs (18 B-cell and 3 T-cell proliferations). Cytogenetic abnormalities were identified in 72% of monomorphic B-cell PTLDs and in all T-cell PTLDs, but in only 15% of polymorphic PTLDs and in no early lesions. The most frequent clonal abnormalities in monomorphic PTLD were trisomies 9 and/or 11 (5 cases), followed by rearrangements of 8q24.1 (4 cases), 3q27 (2 cases), and 14q32 (2 cases). MYC rearrangement (8q24.1) and T-cell-associated chromosomal abnormalities correlated with poor outcome and short survival. PTLD with trisomy 9 and/or 11 developed early after transplant, presenting as Epstein-Barr virus-positive large B-cell lymphoma with prolonged survival.     

Post-transplant lymphoproliferative disorders

Post-transplant lymphoproliferative disorders (PTLD) are the second most frequent neoplasia in transplant patients after skin carcinomas. They occur following both solid organ transplants (SOT) and haematopoietic stem cell transplants (HSCT). Most PTLD in solid organ recipients are of host origin, whereas in HSCT recipients they are most often of donor origin. The EBV status of the recipient and the donor, the type of transplant, the type of immunosuppressive therapy used, and the time after transplant are all important parameters that have been associated with the incidence and the type of PTLD. Although most PTLD are B-cell lesions up to 15% may be T-cell or NK-cell type. Most PTLD are associated with EBV, but EBV-negative PTLD are also clearly recognized. In the 2008 WHO classification of lymphoid neoplasms (ref) PTLD are subclassified according to their histological and immunophenotypic characteristics into early lesions, polymorphic type, monomorphic type, and classical Hodgkin lymphoma-type. Overall PTLD mortality rates are around 50%, but new therapies that include early treatment with rituximab and novel anti-EBV therapies promise better outcomes.     

Transplant-associated lymphoproliferation

Transplantation of solid organs and haematopoietic stem cells requires immunosuppressive drug therapy in order to prevent rejection or graft-versus-host disease. Depending on dosage and type of drug, the risk of developing an Epstein-Barr virus (EBV)-associated post-transplant lymphoproliferative disease (PTLD) is increased. The lesion spectrum ranges from hyperplastic lesions to manifest lymphomas, the latter being classified as monomorphic PTLD. Hyperplastic changes, which are not distinguishable from viral reactions, comprise early or mononucleosis-like lesions. Those with effaced lymph node architecture or extranodal manifestation without a lymphoma-like phenotype are designated polymorphic PTLD. Monomorphic PTLD are either high grade B cell lymphomas, plasma cell neoplasms or Hodgkin lymphomas and only very rarely T cell lymphomas. Low grade B cell lymphomas do not occur. In a subfraction of cases, including even monomorphic PTLD, reduction of immunosuppression alone is sufficient to induce remission of the pathological process.     

Recurrent Epstein-Barr virus-associated post-transplant lymphoproliferative disorder: report of a patient with histologically similar but clonally distinct metachronous abdominal and brain lesions.

A liver transplant patient developed a single central nervous system (CNS) intraparenchymal lesion 5 months after the diagnosis of an intraabdominal diffuse large B-cell post-transplant lymphoproliferative disorder (PTLD). Biopsy of the new CNS lesion showed a diffuse large B-cell PTLD morphologically and immunohistochemically indistinguishable from the abdominal lesion. In addition, both lesions were positive for Epstein-Barr virus (EBV) DNA by polymerase chain reaction (PCR) and for EBV-encoded RNA by in situ hybridization. Although these results were consistent with a metastatic origin for the CNS lesion, the finding of an intraparenchymal lesion without leptomeningeal or dural spread was suggestive of a new primary CNS lymphoma. Proof that the brain lesion was a second primary and not a metastasis was obtained by immunoglobulin gene rearrangement studies and assessment of EBV clonality. Multiple primary lymphoid neoplasms arise at higher frequency in the setting of immunosuppression, and molecular investigations of tumor clonality can provide clinically relevant staging and prognostic information.     

Malignant lymphomas of the nasal cavity and paranasal sinuses. A clinicopathologic and immunohistochemical study.

The clinicopathologic and immunohistological features of 20 Japanese patients with non-Hodgkin's lymphomas (NHLs) limited to the sinonasal area were studied using a broad panel of T- and B-cell markers on paraffin-embedded and fresh frozen tissue. All cases showed a diffuse growth pattern. Nine cases were B-cell lymphomas (immunoblastic n = 4, centroblastic n = 3, immunocytoma n = 1, centrocytic n = 1), and nine were T-cell lymphomas (pleomorphic medium and large cell n = 8, angioimmunoblastic n = 1). In two cases, the cell lineage could not be determined. No morphologic features of angiocentric/angiodestructive lymphoproliferative lesions or lymphoepithelial lesions in ductal or glandular epithelium were seen in our series. Eight (89%) of the nine T-cell tumors and four (44%) of the nine B-cell neoplasms involved both the nasal cavity and paranasal sinuses. Six of the nine T-cell neoplasms showed a clinical presentation of rhinitis, whereas all of the B-cell neoplasms showed tumor masses in the nasal cavity and/or paranasal sinuses. The two-year survival rate for T-cell lymphomas was poorer than that for B-cell lymphomas. The five-year survival of patients with NHLs involving both the nasal cavity and paranasal sinuses was also poorer than that of patients in whom NHLs were limited to the nasal cavity.     

Clinical Characteristics of Monomorphic Post-transplant Lymphoproliferative Disorders

Post-transplant lymphoproliferative disorders (PTLD) are a heterogeneous group of lymphoproliferative disorders associated with immunosuppression and Epstein-Barr virus infection. PTLD is classified into three major categories: early lesions, polymorphic PTLD, and monomorphic PTLD. The majority of monomorphic PTLD cases are non-Hodgkin''s lymphoma of B-cell origin. This retrospective study was conducted to investigate the incidence, clinical manifestation, treatment, and outcomes of monomorphic PTLD among 5,817 recipients of solid organ or allogeneic hematopoietic stem cell transplantation from five institutions. Fourteen patients with monomorphic PTLD were identified (male:female 11:3; median age 42.6 yr, range 24-60). The overall incidence rate was 0.24%. The most common disease type was diffuse large B cell lymphoma (n=7). The median time between the transplant and diagnosis of PTLD was 85.8 months. However, all cases of PTLD after allogeneic hematopoietic stem cell transplantation occurred within 1 yr after transplantation. Ten of the 14 patients had EBV-positive tumor. Fourteen patients received combination systemic chemotherapy and four patients were treated with radiation therapy. Ten patients achieved a complete response (CR) and two patients a partial response (PR). The median follow-up period for surviving patients was 36.6 months. Nine patients remain alive (eight CR, one PR). Nine of 11 solid organ transplantations preserved graft function. The present study indicates a lower incidence rate and a longer median time before the development of PTLD than those of previous reports. Careful monitoring was needed after allogeneic hematopoietic stem cell transplantation for PTLD.     

Histogenetic phenotypes of B cells in posttransplant lymphoproliferative disorders by immunohistochemical analysis correlate with transplant type: solid organ vs hematopoietic stem cell transplantation

We immunohistochemically defined the histogenesis of posttransplantation lymphoproliferative disorders (PTLDs; B-cell phenotype) occurring after allogeneic T cell-depleted hematopoietic stem cell transplantation (HSCT; n = 15) or solid organ transplantation (SOT; n = 11) to determine whether transplantation type or morphologic subtype of PTLD affected the histogenetic subtype. Immunohistochemical stains using histogenetic markers for germinal center (GC) B cells, late GC and post-GC B cells, and post-GC B cells were performed on paraffin-embedded samples. Morphologically, 14 cases were polymorphic; 12 were monomorphic. Histogenetic marker expression was as follows: 1 monomorphic case (4%), GC phenotype expressing bcl-6 and CD10; 17 cases (65%; polymorphic, 9; monomorphic, 8), late GC-early post-GC phenotype expressing MUM1/IRF4; 8 cases (31%; polymorphic, 5; monomorphic, 3), post-GC phenotype expressing MUM1/IRF4 and CD138 but not bcl-6. PTLD cases after HSCT more frequently were post-GC phenotype than after SOT (7/15 vs 1/11, respectively; P = .040) and were independent of morphologic subclassification. Results suggest that most PTLDs are late GC-early post-GC phenotype with a minor group of post-GC phenotype and rare cases of GC phenotype. Findings also suggest a correlation between histogenetic phenotype of B-cell PTLD and type of transplantation.     

Reexamining post-transplant lymphoproliferative disorders: Newly recognized and enigmatic types

Post-transplant lymphoproliferative disorders (PTLD) are a known risk for both solid organ transplant and stem cell transplant recipients. Overall transplant recipients have a six fold increase in risk for developing any kind of non-Hodgkin lymphoma and PTLDs occur in up to 10% of SOT recipients. Several new entities have been accepted or renamed in the 2018 update of the WHO classification of tumors of hematopoietic and lymphoid neoplasms, including florid follicular hyperplasia and extranodal marginal zone lymphomas of mucosa-associated lymphoid tissue (MALT-lymphoma) (excluding common locations such as stomach and salivary gland). Other more rare types of PTLD have been reclassified including EBV-positive mucocutaneous ulcer, which is now a recognized diagnosis in its own right and should not be considered polymorphous PTLD. In this paper newly recognized PTLD entities and more unusual PTLDs will be examined.     

p52 Activation in monomorphic B-cell posttransplant lymphoproliferative disorder/diffuse large B-cell lymphoma without BAFF-R expression

Posttransplantation lymphoproliferative disorders (PTLD) are associated with Epstein-Barr virus (EBV) and activate the NF-κB pathway. B-cell activating factor (BAFF) modulates cell growth and survival in non-Hodgkin's lymphomas. However, there are few studies of EBV, BAFF/BAFF-R signaling, and NF-κB1 and NF-κB2 pathway activation in PTLD. Diffuse large B-cell lymphomas (DLBCL) in two different clinical contexts, immunocompetent patients (DLBCL/IC; n = 30) or posttransplantation solid-organ recipients (DLBCL/PTLD; n = 21), were characterized histogenically as germinal center (GC) or non-germinal center (NGC). Expression of BAFF, BAFF-R, and NF-κB proteins p50 and p52 and the presence or absence of EBV were compared in these clinical contexts. Regardless of the GC or NGC pattern of DLBCL, BAFF-R was expressed in 37% of DLBCL/IC but in only 4.8% of DLBCL/PTLD. p52 was expressed in DLBCL/PTLD/NGC (12 of 19 cases) as compared with DLBCL/IC/NGC (0 of 18 cases). This pattern might be related to the presence of EBV and latent membrane protein 1 because p52 expression was observed primarily in EBV-positive DLBCL/PTLD cases expressing latent membrane protein 1. Thus, the activation profile or NGC pattern of DLBCL/PTLD was not associated with BAFF/BAFF-R expression, whereas nuclear p52 related to NF-κB2 pathway activation might be linked to EBV.     

Application of a fluorescent PCR method for molecular diagnosis of posttransplant lymphoproliferative disorders on routine tissue sections.

Molecular detection of monoclonality can play an important role in the diagnosis of posttransplantation lymphoproliferative disorders (PTLD). To permit accurate molecular diagnosis of PTLD even on very small amounts of DNA extracted from routinely embedded histologic material, we adapted a commercially available PCR protocol (for FR-1, -2 and -3 regions), originally designed for use on fresh/frozen samples. We applied this approach on routine biopsy/surgical material of 10 PTLD (from nine patients). All three FR regions were always amplified, indicating that the extracted DNA was of medium quality. All five PTLD morphologically classified as lymphomas were monoclonal in at least one FR region. Thus, using the WHO histologic, immunohistochemical, and clinical criteria as the reference standard, the approach provided 100% sensitivity for detection of monoclonal malignancies, supporting the validity of the method. Of five specimens classified morphologically as polymorphic PTLD, three displayed a solitary IgH gene rearrangement peak, consistent with the presence of a monoclonal B-cell population (ie, monoclonal polymorphic PTLD). This rapid and straightforward procedure, which allows identification of a wide range of IgH rearrangements, could facilitate molecular analysis of PTLD in routine practice, while limiting consumption of valuable diagnostic material.     

Patterns of liver infiltration in lymphoproliferative disease

Aims:  Liver involvement is a common finding in patients suffering from lymphoproliferative disease, and histopathological patterns of infiltration vary according to lymphoma subtype. Data correlating the form of liver involvement with distinct lymphoma subtypes is, however, scarce. The aim was to review 89 liver biopsies diagnosed with lymphoma infiltration and evaluate the infiltration patterns.
Methods and results:  In equivocal cases, additional immunohistochemical and molecular pathology analyses were performed to differentiate between neoplastic and reactive cell infiltrates and to classify the lymphoma subtypes. Diffuse large B-cell lymphoma (DLBCL), chronic lymphocytic leukaemia (CLL), Hodgkin's lymphoma (HL) and Burkitt lymphoma (BL) were the most prevalent subtypes in our series, which included 14 different lymphoma entities in total. Whereas DLBCL and BL predominantly demonstrated tumour nodules deranging the normal hepatic architecture, CLL and HL mostly showed infiltration of the portal fields. Interestingly, distinct lymphoma entities, particularly marginal zone B-cell lymphomas (MZL) and HL, commonly revealed lympho-epithelial lesions of bile ducts, which were observed in 10% of all investigated cases. Four cases, initially interpreted as T-cell lymphomas, proved to be reactive T-cell lesions.
Conclusions:  Distinct lymphoma subtypes show characteristic patterns of liver infiltration. Additional molecular analyses can support diagnosis by verification of clonality or detection of characteristic genetic aberrations.     

移植后淋巴组织增生性疾病的临床病理分析

目的探讨移植后淋巴组织增生性疾病（PTLD）的临床及病理特征,提高其诊断和治疗水平。方法对4例移植后淋巴组织增生性疾病行HE和免疫组织化学EnVision法染色、原位杂交及聚合酶链反应,复习其临床资料并随访。结果4例中3例是肾移植后,其中2例为多形性PTLD,1例为单形性PTLD;另1例是异体骨髓移植后PTLD的“早期”病变。2例EB病毒阳性。4例移植后所用免疫抑制剂均以环孢A类药为主,辅以激素。例1～4从移植到诊断PTLD的时间为42、7、129、2个月。例3多形性PTLD的临床分期为Ⅱ期（诊断PTLD后2个月死亡）;其余均为Ⅰ期。均存活,诊断PTLD后生存期为40（例1）、26（例2）、5（例4）个月。结论PTLD是发生在器官移植后,具有独特的形态和临床特征的淋巴组织增生性疾病,部分病例与EB病毒感染有关。其预后与临床分期相关,免疫抑制剂减量可能有效。     

B lymphocytes and Epstein-Barr virus: the lesson of post-transplant lymphoproliferative disorders

Epstein-Barr virus (EBV) is a ubiquitous human gamma-herpes virus that establishes a life-long asymptomatic infection in immunocompetent hosts by colonizing memory B lymphocytes and hijacking cellular signaling pathways that regulate antigen-dependent B-cell activation and differentiation. In patients with solid organ or hematopoietic stem cell transplantation, the defect in EBV-specific immune responses may allow the outgrowth of EBV-carrying B lymphocytes that may give rise to a spectrum of different clinico-pathologic entities encompassed by the term post-transplantation lymphoproliferative disorders (PTLD). EBV-driven immortalization of B-cells is mediated by the cooperative activity of viral proteins that derange critical cellular pathways controlling growth and/or survival of B lymphocytes. Full transformation of infected B-cells is achieved by the contribution of poorly defined additional co-factors, including microenvironmental stimuli, genetic and epigenetic alterations. The quantification of circulating EBV DNA and EBV-specific T cells are valuable tools in the clinical monitoring of EBV-associated PTLD. The recent advances in elucidation of the mechanisms underlying EBV-induced growth transformation will be instrumental in guiding the design of novel approaches for the treatment of these often life-threatening lymphoproliferative disorders.     

The role of gene rearrangements for antigen receptors in the diagnosis of lymphoma obtained by fine-needle aspiration. A study of 63 cases with concomitant immunophenotyping

To assess the efficacy of performing genotyping in addition to immunophenotyping as an adjunct to cytologic diagnosis, 63 consecutive patients with fine-needle aspirates of lymphoproliferative lesions who had concurrent immunophenotyping and genotyping performed on fine-needle aspirate cell suspensions were studied. Thirty-nine of 63 specimens (62%) that appeared to contain non-Hodgkin's lymphoma and that proved to be of B-cell lineage by genotyping were accurately phenotyped and shown to be monotypic for immunoglobulin light chains by cell suspension immunocytochemistry. Genotyping facilitated lineage assignment and/or confirmed clonality in 17 of 63 specimens (27%) that were difficult to determine based on morphologic data. These include cases of atypical lymphoid proliferations with polyclonal or inconclusive markers (n = 6), peripheral T-cell lymphoma (n = 3), extracutaneous mycosis fungoides (n = 1), lymphoblastic lymphoma (n = 4), null cell lymphoma (n = 1), and specimens with equivocal or technically unsatisfactory markers (n = 2). Based on these results, it is proposed that genotyping for lineage assignment and/or clonality be performed to include cases of atypical lymphoid proliferations, T-cell malignant neoplasms, lymphoid malignant neoplasms with equivocal markers, and differentiation of lymphoid from nonlymphoid neoplasms. Genotyping by antigen-receptor gene rearrangement appears to be redundant in cases with mature B-cell phenotypes that demonstrate monoclonality by immunophenotyping.     

Overview of 2008 WHO Classification of Malignant Lymphoma

Lymphoma classification is now evolving. The 4th edition of the WHO Classification of Tumors of Hematopoietic and Lymphoid Tissues was published in 2008, regarded as a revised and updated version of the 2001 3rd edition; an effort that involved 138 authors from 22 countries and two clinical advisory committees comprising 62 clinical specialists with expertise in lymphoid and myeloid disorders. New aspects of the 2008 WHO classification can be briefly summarized as follows: 1) a greater recognition of "early" lesions, i.e., an incipient neoplasm, e.g., in situ follicular lymphoma, has been incorporated; 2) age was highlighted as a defining feature of some neoplasms, e.g., EBV+ diffuse large B-cell lymphoma of the elderly, pediatric follicular lymphoma, and EBV+ T-cell lymphoproliferative diseases of childhood; 3) anatomical sites were noted as having an important impact on disease definitions; and 4) newly recognized borderline categories were listed on the basis of their biological overlap between diffuse large B-cell lymphoma and Burkitt lymphoma or classical Hodgkin lymphoma.     

Simian virus 40 in posttransplant lymphoproliferative disorders

Simian virus 40 (SV40) is an oncogenic DNA virus, which is an emergent pathogen implicated in some human malignancies, including B-cell lymphomas. As with other malignancies that occur during immunosuppression, it is hypothesized that SV40 infections may be associated with some posttransplant lymphoproliferative disorders (PTLDs). Specimens were tested initially for Epstein-Barr virus (EBV) by in situ hybridization for EBV-encoded small RNA and/or by immunohistochemical staining for EBV-latent membrane protein 1. Coded DNA specimens extracted from formalin-fixed, paraffin-embedded tissues from 22 PTLD cases were examined by polymerase chain reaction using primers for the SV40 large tumor antigen (T-ag) gene and confirmed by sequence analysis. In addition, samples were assessed for the expression of SV40 T-ag by immunohistochemical staining. Epstein-Barr virus was detected in 18 (82%) of 22 PTLD cases. Simian virus 40 T-ag sequences were detected in 2 (13%) of the 16 cases with amplifiable DNA: one with EBV-negative T-cell PTLD and the other with EBV-positive B-cell monomorphic PTLD. Immunohistochemical staining showed expression of SV40 T-ag in 1 of 2 cases containing viral DNA sequences and in none of the SV40 T-ag DNA-negative samples. Expression of SV40 T-ag was restricted to malignant cells and not to reactive lymphocytes. These results suggest that SV40 may be associated with a small subset of PTLD cases. Additional studies are needed to determine the role of SV40 in EBV-negative PTLD.