Molecular genetic analysis demonstrates that multiple posttransplantation lymphoproliferative disorders occurring in one anatomic site in a single patient represent distinct primary lymphoid neoplasms

Fifth Edition of the World Health Classification of Tumors of the Hematopoietic and Lymphoid Tissues: B-cell Neoplasms

We review B-cell neoplasms in the 5th edition of the World Health Organization classification of hematolymphoid tumors (WHO-HEM5). The revised classification is based on a multidisciplinary approach including input from pathologists, clinicians, and other experts. The WHO-HEM5 follows a hierarchical structure allowing the use of family (class)-level definitions when defining diagnostic criteria are partially met or a complete investigational workup is not possible. Disease types and subtypes have expanded compared with the WHO revised 4th edition (WHO-HEM4R), mainly because of the expansion in genomic knowledge of these diseases. In this review, we focus on highlighting changes and updates in the classification of B-cell lymphomas, providing a comparison with WHO-HEM4R, and offering guidance on how the new classification can be applied to the diagnosis of B-cell lymphomas in routine practice.

Post-transplant lymphoproliferative disorders (PTLD) in adolescents and young adults: A category in need of definition

Post-transplant lymphoproliferative disorders are a well-recognized complication of solid organ and stem cell transplantation. Much data has accumulated with respect to the pathobiology and clinical behavior of these lesions in the general post-transplant population as well as in the pediatric and adult age groups. However, information as to these lesions in the adolescent and young adult populations, which bridge the pediatric and adult groups, is limited. In this review, the focus is on this unique population of PTLD patients and their proliferations.

Three different histological subtypes of Epstein-Barr virus-negative post-transplant lymphoproliferative disorder in a patient with hepatitis C infection

We report a rare case in which Epstein-Barr virus (EBV)-negative polymorphic B-cell post-transplant lymphoproliferative disorder (PTLD) and EBV-negative monomorphic T-cell PTLD [anaplastic lymphoma kinase (ALK)-positive anaplastic large cell lymphoma (ALCL)] were observed simultaneously in the same cervical lymph node, 34 months after liver transplantation for hepatitis C liver cirrhosis. Although hepatitis C recurred after 2 months, he had no other complications until PTLD occurred 34 months post-transplantation. The patient underwent reduction of the immunosuppressive drug and rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone therapy, and he was considered to have achieved complete remission. However, PTLD recurred, and he died 6 months after the initial diagnosis. Autopsy revealed only EBV-negative monomorphic T-cell PTLD (ALK-negative ALCL) that involved the liver, spleen, bilateral kidneys, stomach, bladder, heart, bone marrow, right ureter, and pons. Thus, recurrent PTLD may show a different histological type from the primary disorder, as PTLD has a multiclonal potentiality that causes various types of lymphomas. Therefore, it may be difficult to predict PTLD-related prognosis from the initial PTLD histological identification.

Plasma markers of B-cell activation and clonality in pediatric liver and hematopoietic stem cell transplant recipients

BACKGROUND

Transplant recipients are at risk of posttransplant lymphoproliferative disease (PTLD).

METHODS

Thirty-six pediatric transplant recipients were evaluated (18 hematopoietic stem cell and 18 liver recipients; 12 had PTLD). We studied 207 longitudinal plasma samples from these recipients for three markers of B-cell activation or clonality: immunoglobulin free light chains (FLCs), soluble CD30 (sCD30), and monoclonal immunoglobulins (M-proteins).

RESULTS

Kappa FLCs, lambda FLCs, and sCD30 were elevated in 20.8%, 28.0%, and 94.2% of plasma specimens, respectively. Free light chain and sCD30 levels increased significantly 1.18 to 1.82 fold per log10 Epstein-Barr virus (EBV) load in peripheral blood. Five PTLD cases manifested elevated FLCs with an abnormal kappa/lambda ratio, suggesting monoclonal FLC production. M-proteins were present in 91% of PTLD cases versus 50% to 67% of other recipients with high or low EBV loads (P=0.13). Concordance of FLCs, M-proteins, and PTLD tumor light chain restriction was imperfect. For example, one PTLD case with an IgG lambda M-protein had a tumor that was kappa restricted, and another case with an M-protein had a T-cell PTLD. In an additional case, an IgM kappa M-protein and excess kappa FLCs were both detected in plasma at PTLD diagnosis; although the tumor was not restricted at diagnosis, kappa restriction was present 5 years later when the PTLD relapsed.

CONCLUSIONS

Plasma markers of B-cell dysfunction are frequent after transplantation and associated with poor EBV control. These abnormal markers may be produced by oligoclonal B-cell populations or PTLD tumor cells and could potentially help identify recipients at high risk of PTLD.

Early posttransplant lymphoproliferative disease: clinicopathologic features and correlation with mTOR signaling pathway activation

Early posttransplant lymphoproliferative disorders (EPTLDs) represent the first changes in posttransplant lymphoproliferative disorders (PTLDs) morphologic spectrum. EPTLD data are available mostly from case reports and series that include other types of PTLD. Fifteen EPTLDs were reviewed retrospectively. Clinical data, histopathology, clonality, and Epstein- Barr virus (EBV) status were correlated with staining intensity to an antibody for phosphorylated S6 (pS6) ribosomal protein, a downstream effector of mammalian target of rapamycin (mTOR). Median time from transplantation to EPTLD was 50 months (range, 7-135 mo). EPTLDs involved tonsil and/or adenoids (n = 11) and lymph nodes (n = 4), all of which were nonclonal and EBV-encoded RNA-positive. Most (n = 11) were plasmacytic hyperplasia and florid follicular hyperplasia (n = 4). All regressed with reduced immunosuppression, and had increased pS6 staining compared with normal tonsil (P = .002, F test). EPTLDs developed later than previously reported, involved mostly tonsils/adenoids, were EBV-encoded RNA (EBER) positive, showed increased pS6, and had excellent clinical outcome with reduction of immunosuppression.

Post-transplant lymphoproliferative disorders following solid-organ transplantation

A post-transplant lymphoproliferative disorder (PTLD) is an uncommon but serious complication following solid-organ transplantation. The incidence varies, depending on the type of organ transplanted, the degree of immunosuppression, the number of episodes of acute rejection and a patient's immune status to Epstein-Barr virus. The incidence of PTLD is thought to be bimodal; cases in the first year after solid-organ transplantation are typically related to Epstein-Barr virus. A second incidence occurs more than 1 year following transplantation and is typically not related to Epstein-Barr virus. A variety of therapeutic approaches has been used for these patients, with more recent strategies including the use of rituximab, with or without combination chemotherapy. Efforts continue to be made to improve the outcome of patients with PTLD.

Posttransplantation lymphoproliferative disease involving the pituitary gland

Posttransplantation lymphoproliferative disorders (PTLD) are heterogeneous lesions with variable morphology, immunophenotype, and molecular characteristics. Multiple distinct primary lesions can occur in PTLD, rarely with both B-cell and T-cell characteristics. Lesions can involve both grafted organs and other sites; however, PTLD involving the pituitary gland has not been previously reported. We describe a patient who developed Epstein-Barr virus-negative PTLD 13 years posttransplantation involving the terminal ileum and pituitary, which was simultaneously involved by a pituitary adenoma. Immunohistochemistry of the pituitary lesion showed expression of CD79a, CD3, and CD7 with clonal rearrangements of both T-cell receptor gamma chain (TRG@) and immunoglobulin heavy chain (IGH@) genes. The terminal ileal lesion was immunophenotypically and molecularly distinct. This is the first report of pituitary PTLD and illustrates the potentially complex nature of PTLD.

Posttransplant lymphoproliferative diseases

The risk of developing cancer after solid organ transplantation (SOT) is about 5- to 10-fold greater than that of the general population. The cumulative risk of cancer rises to more than 50% at 20 years after transplant and increases with age, and so children receiving transplants are at high risk of developing a malignancy. Posttransplant lymphoproliferative disease (PTLD) is the most common cancer observed in children following SOT, accounting for half of all such malignancies. PTLD is a heterogeneous group of disorders with a wide spectrum of pathologic and clinical manifestations and is a major contributor to long-term morbidity and mortality in this population. Among children, most cases are associated with Epstein-Barr virus infection. This article reviews the pathology, immunobiology, epidemiology, and clinical aspects of PTLD, underscoring the need for ongoing systematic study of complex biologic and therapeutic questions.

CNS or bone marrow involvement as risk factors for poor survival in post-transplantation lymphoproliferative disorders in children after solid organ transplantation

PURPOSE

To identify prognostic factors of survival in pediatric post-transplantation lymphoproliferative disorder (PTLD) after solid organ transplantation.

PATIENTS AND METHODS

A multicenter, retrospective case analysis of 55 pediatric solid organ graft recipients (kidney, liver, heart/lung) developing PTLD were reported to the German Pediatric-PTLD registry. Patient charts were analyzed for tumor characteristics (histology, immunophenotypes, cytogenetics, Epstein-Barr virus [EBV] detection), stage, treatment, and outcome. Probability of overall and event-free survival was analyzed in defined subgroups using univariate and Cox regression analyses.

RESULTS

PTLD was diagnosed at a median time of 29 months after organ transplantation, with a significantly shorter lag time in liver (0.83 years) versus heart or renal graft recipients (3.33 and 3.10 years, respectively; P = .001). The 5-year overall and event-free survival was 68% and 59%, respectively, with 59% of patients surviving 10 years. Stage IV disease with bone marrow and/or CNS involvement was associated independently with poor survival (P = .0005). No differences in outcome were observed between early- and late-onset PTLD, monomorphic or polymorphic PTLD, and EBV-positive or EBV-negative PTLD, respectively. Patients with Burkitt or Burkitt-like PTLD and c-myc translocations had short survival (< 1 year).

CONCLUSION

Stage IV disease is an independent risk factor for poor survival in pediatric PTLD patients. Prospective multicenter trials are needed to delineate additional risk factors and to assess treatment approaches for pediatric PTLD.

The clinicopathologic spectrum of posttransplantation lymphoproliferative disorders

CONTEXT

Posttransplantation lymphoproliferative disorders (PTLDs) are a heterogeneous group of lymphoid proliferations occurring in the setting of solid organ or bone marrow transplantation. They show a clinical, morphologic, and molecular genetic spectrum ranging from reactive polyclonal lesions to frank lymphomas. The close association with Epstein-Barr virus has been established and the pathogenetic role of this virus is becoming better understood. Although they are relatively uncommon, PTLDs are a significant cause of morbidity and mortality in transplant patients.

OBJECTIVE

To review the incidence, risk factors, clinical features, pathogenesis, and classification of PTLDs.

DATA SOURCES

We reviewed relevant articles indexed in PubMed (National Library of Medicine), with emphasis on more recent studies. The classification of PTLDs is based on the most current World Health Organization classification text.

CONCLUSIONS

Posttransplantation lymphoproliferative disorders are a heterogeneous group of disorders showing a wide clinical and morphologic spectrum. Although relatively uncommon, PTLDs represent a serious complication after transplantation. Many risk factors for PTLD are well established, including transplanted organ, age at transplant, and Epstein-Barr virus seronegativity at transplant. However, other factors have been implicated and still require additional examination. Recent studies are shedding some light on the pathogenesis of PTLDs and defining relevant pathways related to Epstein-Barr virus. As the pathogenesis of PTLDs is further elucidated, the classification of PTLDs will most likely evolve.

Evidence for a Multiclonal Origin of Multicentric Advanced Lesions of Kaposi Sarcoma

BACKGROUND

Kaposi sarcoma (KS) is a complex tumor of uncertain clonality. Studying the viral clonality of the human herpesvirus 8 (HHV-8) in KS to determine clonality of the tumors, a strategy that has been used previously with Epstein-Barr virus and its associated tumors, may elucidate whether multicentric (disseminated) KS lesions correspond to metastatic lesions or to expansions of independent clones.

METHODS

A series of 139 KS biopsies (from skin, lymph node, or tonsil) was obtained from 98 patients, with 59 biopsies from 18 patients with disseminated multicentric KS skin lesions. The degree of spindle cell infiltration in biopsies was established by direct observation of hematoxylin-eosin-stained sections, and HHV-8 viral load was quantified by real-time polymerase chain reaction. To determine cellular clonality, the size heterogeneity of the HHV-8-fused terminal repeat (TR) region was determined by probing of electrophoresed restricted genomic DNA from KS biopsies for the HHV-8 TR sequence.

RESULTS

HHV-8 clonality analysis was performed on the 62 samples for which sufficient DNA was obtained. Most samples corresponded to histologically nodular lesions with high spindle cell infiltration and high viral load. A clonal HHV-8 pattern was determined for 59 samples; 11 were found to be monoclonal and 48 to be oligoclonal. The informative samples that were from disseminated KS skin lesions (n = 26, from six patients) were either monoclonal or oligoclonal, and the size of HHV-8 episomes varied between these samples.

CONCLUSION

Although some tumor KS lesions were monoclonal expansions of HHV-8-infected spindle cells, most advanced lesions were oligoclonal proliferations. Furthermore, individual KS disseminated tumor skin lesions were found to represent distinct expansions of HHV-8-infected spindle cells. Thus, our results suggest that KS lesions, especially in patients with advanced skin tumors, are reactive proliferations rather than true malignancies with metastatic dissemination.

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.

Posttransplant Lymphoproliferative Disorder in a Kidney-Pancreas Transplanted Recipient

Posttransplant lymphoproliferative disorders (PTLDs) are lymphoid proliferations or lymphomas that develop as a consequence of immunosuppression after solid organ or bone marrow transplantation and are mostly associated with an Epstein-Barr virus infection. The morphologic categories include different types of benign and malignant lymphoid proliferations. The majority of PTLDs is of B-cell origin with clonal rearrangements of the immunoglobulin genes. The PTLDs in solid organ transplants are reported to be either of host or of donor origin. Donor-related PTLDs frequently involve the allograft. We report a case of a 52-year-old woman recipient who developed simultaneously PTLDs in several organs 5 month after receiving a sex-mismatched renal and pancreas allograft. Immunosuppression regimen comprised antithymocyte globulin, tacrolimus, mycophenolate mofetil, and steroids. Pathologic features appeared as polymorphic PTLDs in the renal allograft, liver, and central nervous system (CNS). Molecular genetic studies revealed different clonal immunoglobulin heavy chain gene rearrangements in all 3 organs as determined by polymerase chain reaction (PCR). Epstein-Barr virus were detected by nested PCR and in situ hybridization in all 3 tumors. The PTLDs in liver and CNS were of host origin whereas the allograft kidney PTLD was found to originate from the male donor as shown by the simultaneous detection of female and male sex chromosomes by PCR and fluorescence in situ hybridization. The recipient died in consequence of the CNS involvement, after intracerebral hemorrhage with uncal and tonsillar herniation.

Micronodular thymoma: an epithelial tumour with abnormal chemokine expression setting the stage for lymphoma development

The aetiology of primary B-cell lymphomas of the thymus is enigmatic. Although thymic follicular lymphoid hyperplasia (TFH) is commonly associated with myasthenia gravis (MG), lymphoma is not a complication of this condition. The present paper reports a high frequency of monoclonal B-cell populations (6 of 18 cases; 33%) in micronodular thymoma (MNT), a peculiar thymic epithelial neoplasm with a B-cell-rich stroma, while B cells were consistently polyclonal in TFH (25 cases) and other types of thymomas (15 cases) (p < 0.001). An intratumoural lymphoma could be identified in three of the six monoclonal MNTs. Sequencing of the monoclonal IgH chain revealed partially overlapping VDJ gene usage in MNT and thymic mucosa-associated lymphoid tissue (MALT) lymphomas. The neoplastic epithelium of MNTs, but not of TFH and other types of thymoma, expressed high levels of dendritic cell, T-cell, and B-cell chemoattractants, such as CCL18, CCR6, and CCL20. It is concluded that abnormal chemokine expression in an epithelial tumour, MNT, can promote the recruitment of MALT, the emergence of monoclonal B cells, and, eventually, the subsequent development of mediastinal lymphomas. More generally, the concept that expression of a 'high-risk' spectrum of chemokines due to local or genetic factors may interfere with B-cell homeostasis and may contribute to MALT lymphoma development in chronic inflammatory states is proposed.

Post-transplant lymphoproliferative disorders: implications for acquired immunodeficiency syndrome-associated malignancies

Post-transplant lymphoproliferative disorders (PTLDs) comprise a histologic spectrum, ranging from hyperplastic-appearing lesions to frank non-Hodgkin's lymphoma or multiple myeloma histology. Multiple clones may coexist, each representing a discrete lymphomagenic event, a situation that is unique to immunodeficiency states. The incidence varies from 1% in renal recipients to 5% in heart recipients, but can be markedly increased by the use of anti-T-cell therapies or by T-cell depletion in bone marrow transplantation. PTLD continues to arise, even many years after transplantation, and late T-cell lymphomas have recently been recognized. Pretransplant Epstein-Barr virus (EBV) seronegativity increases risk to as high as 30%-50%. PTLD has a highly variable clinical picture; certain patterns are, however, seen. Reversibility of PTLD with reduction in immunosuppressives has long been recognized. Predicting reversibility has been difficult. The presence or absence of bcl-6 mutations has recently been identified as being of predictive value. Surgical resection can be curative. Cytotoxics, although problematic, can also be curative. Long-term remission has been achieved with anti CD21 and CD24 antibodies; efficacy has been reported for interferon alfa and for rituximab. In vitro expanded EBV-specific T cells have been effective as treatment and as prophylaxis in the setting of bone marrow transplantation. EBV viral load measured in blood appears to associate with the emergence of PTLD and may facilitate prophylactic studies. PTLD is a model of immunodeficiency-related EBV lymphomagenesis. Pathogenetic, therapeutic, and prophylactic insights gained from the study of PTLD are likely to be applicable to the acquired immunodeficiency syndrome setting.

Human immunodeficiency virus (HIV)-associated polymorphic lymphoproliferative disorders

The majority of AIDS-related non-Hodgkin's lymphomas are clinically aggressive monoclonal B-cell Burkitt's lymphomas, large cell lymphomas, or immunoblastic lymphomas. In contrast, the lymphoid proliferations arising in solid organ transplant recipients, collectively referred to as posttransplantation lymphoproliferative disorders (PT-LPDs), represent a clinically and histopathologically heterogeneous group of Epstein-Barr virus (EBV)-driven B-cell proliferations of variable clonal composition. During a retrospective histopathologic review of lymphoid proliferations associated with human immunodeficiency virus (HIV) infection we identified 10 cases that morphologically resemble the polymorphic PT-LPDs. They arose in lymph nodes (five), lungs (two), and the parotid gland, perineum, and skin (one each). They exhibit a diffuse growth pattern and are composed of a polymorphic lymphoid cell population exhibiting a variable degree of plasmacytic differentiation, cytologic atypia, and numbers of atypical immunoblasts. A clonal B-cell population was detected by immunoglobulin heavy and light chain gene rearrangement and/or EBV terminal repeat analysis in 8 of the 10 (80%) cases by Southern blotting. The nongermline hybridizing bands were usually faint, however, suggesting that the clonal B-cell population represented only a subpopulation within the polymorphic lesion. Strong clonal rearrangement bands were present in one case in which there was clear morphologic evidence of transformation to diffuse large cell lymphoma. This case exhibited C-MYC, BCL-6, and p53 gene mutations. One other case exhibited a p53 gene mutation. The remaining eight cases lacked C-MYC, BCL-6, RAS, and p53 gene alterations. Clonal EBV infection was detected in 4 of the 10 (40%) lesions. Like EBV-containing PT-LPDs, all four EBV-positive HIV-associated polymorphic lesions were associated with type A EBV. The Kaposi's sarcoma-associated herpesvirus was detectable in two cases by polymerase chain reaction analysis, but not by Southern blotting. In situ hybridization demonstrated Kaposi's sarcoma-associated herpesvirus in some of the cytologically malignant-appearing cells. In conclusion, polymorphic B-cell lymphoproliferative disorders comparable morphologically and molecularly to those arising after solid organ transplantation also occur in association with HIV infection. As in the case of their polymorphic PT-LPD counterparts, their malignant status, biologic significance, and relationship to monomorphic B-cell lymphomas remain to be elucidated.

Orbital presentation of posttransplantation lymphoproliferative disorder: a small case series

OBJECTIVE

To describe a small series of patients with orbital presentation of posttransplantation lymphoproliferative disorder (PTLD).

DESIGN

Retrospective, interventional case series.

PARTICIPANTS

Three patients with orbital presentation of histologically diagnosed PTLD.

METHODS

Review of medical records.

MAIN OUTCOME MEASURES

Measured parameters included vision, proptosis, and tumor extent.

RESULTS

Three cases of orbital PTLD are described. In two of the cases, the tumor initially demonstrated orbital signs and symptoms, whereas in the third case, orbital and systemic signs were synchronous. Two of three patients had disseminated disease discovered at the time of presentation. One adult patient had synchronous presentation of PTLD in the orbit and prostate. One pediatric patient had tumor dissemination to the liver at the time of presentation. The PTLD tumors were classified histologically as diffuse large cell lymphoma of monomorphic or immunoblastic type in all three cases. Treatment included local irradiation, decreased immunosuppression, and antilymphocyte monoclonal antibodies.

CONCLUSIONS

Orbital presentation is a rare manifestation of PTLD. However, ophthalmologists must consider this diagnosis carefully in organ transplant recipients with subtle orbital signs and symptoms at presentation. Early detection may alter prognosis. In each case presented, the diagnosis was established via lesion biopsy and subsequent histologic or flow cytometric evaluation, or both.

Successful treatment of posttransplantation lymphoproliferative disorder (PTLD) following renal allografting is associated with sustained CD8(+) T-cell restoration

Posttransplantation lymphoproliferative disorder (PTLD) is a life-threatening Epstein-Barr virus (EBV)-associated B-cell malignancy occurring in 1% to 2% of renal transplantation patients. Host- and PTLD-related factors determining the likelihood of tumor response following reduction of immune suppression (IS) and antiviral therapy remain largely unknown. Standard therapy for PTLD is not well established. Eleven consecutive renal transplantation patients who developed EBV-positive PTLD 8 to 94 months after allografting were uniformly treated with acyclovir and IS reduction. All PTLDs were EBV-positive diffuse large B-cell lymphomas. Ten patients (91%) obtained a durable complete response (CR), and 9 (82%) have remained in continuous CR with a median follow-up of 29 months. Five patients (45%) lost their allograft. Of these, 4 patients had PTLD affecting the transplanted kidney. Peripheral blood CD8(+) T cells increased significantly (P =.0078) from baseline in 8 responders available for analysis. One of 2 patients whose absolute CD8(+) T-cell count subsequently dropped to baseline after IS reduction relapsed. The expanded CD8(+) T cells from 2 responders specifically recognized an immunodominant peptide from the EBV lytic gene BZLF-1. Another lytic EBV gene, thymidine kinase, was expressed in all 8 PTLDs tested. IS reduction and antiviral therapy for PTLD after renal transplantation is a highly successful therapeutic combination, but the risk of graft rejection is significant, particularly in patients with PTLD involving the renal allograft. A sustained expansion of CD8(+) T cells and a cellular immune response to EBV lytic antigens may be important for PTLD clearance in renal transplantation patients.

Posttransplant lymphoproliferative disorders in lung transplant patients: the Cleveland Clinic experience

PTLD is a well-recognized complication of organ transplantation. Large series of heart, renal, and liver transplants have been examined for the incidence and behavior of PTLD. However, reports of the incidence and characteristics of PTLDs in lung transplant (LTx) patients are few. We report our experience with PTLDs in a large series of LTx recipients at a single institution and compare them to other solid organ transplant recipient PTLDs seen at our institution. Twenty-eight patients were found to have PTLD, of whom 8 were lung transplant recipients. We evaluated nine PTLD specimens from these 8 patients for their histology, immunophenotype (CD20, CD3, EBV-LMP1), EBER status by in situ hybridization, and clinical features. The incidence of PTLD was 3.3% (8/244 patients). The time to development of PTLD, after transplant, was short (median time, 7 mo). All were of B-cell lineage. Overall, EBV was demonstrated in 77.7% (7 of 9 specimens) of PTLDs. All specimens tested for clonality were found to be monoclonal. Five patients died, with a median time to death of only 4.6 months. PTLDs in LTx patients are EBV-associated B-cell, predominantly monoclonal lymphoid lesions similar to other solid organ transplant PTLDs. Compared with other solid organ transplant recipients with PTLD at our institution, PTLDs in LTx patients have a propensity to involve the transplanted organ (P =.001, Fisher's exact test), occur earlier after transplant (P =.003, Wilcoxon test), and have a shorter survival (P =.002, log rank test). Reasons for this may include the relatively higher level of immunosuppression required in these patients and limited options in decreasing it. Although the incidence is low, careful early monitoring of lung transplantation patients is warranted because of the poor prognosis of patients developing this complication.

Survival and clonal expansion of mutating "forbidden" (immunoglobulin receptor-deficient) epstein-barr virus-infected b cells in angioimmunoblastic t cell lymphoma

Angioimmunoblastic lymphadenopathy with dysproteinemia (AILD) is a peculiar T cell lymphoma, as expanding B cell clones are often present besides the malignant T cell clones. In addition, large numbers of Epstein-Barr virus (EBV)-infected B cells are frequently observed. To analyze the differentiation status and clonal composition of EBV-harboring B cells in AILD, single EBV-infected cells were micromanipulated from lymph nodes of six patients with frequent EBV(+) cells and their rearranged immunoglobulin (Ig) genes analyzed. Most EBV-infected B cells carried mutated Ig genes, indicating that in AILD, EBV preferentially resides in memory and/or germinal center B cells. EBV(+) B cell clones observed in all six cases ranged from small polyclonal to large monoclonal expansions and often showed ongoing somatic hypermutation while EBV(-) B cells showed little tendency for clonal expansion. Surprisingly, many members of expanding B cell clones had acquired destructive mutations in originally functional V gene rearrangements and showed an unfavorable high load of replacement mutations in the framework regions, indicating that they accumulated mutations over repeated rounds of mutation and division while not being selected through their antigen receptor. This sustained selection-free accumulation of somatic mutations is unique to AILD. Moreover, the survival and clonal expansion of "forbidden" (i.e., Ig-deficient) B cells has not been observed before in vivo and thus represents a novel type of viral latency in the B cell compartment. It is likely the interplay between the microenvironment in AILD lymph nodes and the viral transformation that leads to the survival and clonal expansion of Ig-less B cells.

Atypical Lymphoproliferative Diseases

This review addresses the clinical presentation, pathology, and therapy of several uncommon lymphoid proliferations. Because these lymphoproliferations span the characteristics of reactive polymorphous proliferations to clonal malignant neoplasms, they are often difficult to diagnose and treat effectively.

In Section I, Dr. Greiner describes the pathology of the spectrum of atypical lymphoid disorders including Castleman's disease, angioimmunoblastic lymphadenopathy, lymphadenopathy in autoimmune diseases, posttransplant lymphoproliferative disorders, and X-linked lymphoproliferative disorder. The relationship to Epstein-Barr virus (EBV) and human herpsesvirus-8 (HHV-8) is discussed, and molecular diagnostic assays and principles for obtaining proper diagnostic evaluation are emphasized.

In Section II, Dr. Armitage presents a practical approach to the management of Castleman's disease. The discussion includes the importance of confirmation of the histological diagnosis and careful staging evaluation, therapeutic options, and the increased risks for infection and lymphoma. The appropriate roles of surgical excision, corticosteroids, and combination chemotherapy are addressed along with alternative strategies such as anti-interleukin-6 and bone marrow transplantation.

In Section III, Dr. Gross reviews the treatment of EBV-associated lymphoproliferative disorders in primary immunodeficiencies and in post-transplant patients. He gives an update on the recent molecular discoveries in X-linked lymphoproliferative disorder. Preliminary results of a phase II trial of low-dose cyclophosphamide in posttransplant lymphoproliferative disorders and the use of GM-CSF as preemptive therapy are presented.

Atypical Lymphoproliferative Diseases

This review addresses the clinical presentation, pathology, and therapy of several uncommon lymphoid proliferations. Because these lymphoproliferations span the characteristics of reactive polymorphous proliferations to clonal malignant neoplasms, they are often difficult to diagnose and treat effectively.

In Section I, Dr. Greiner describes the pathology of the spectrum of atypical lymphoid disorders including Castleman's disease, angioimmunoblastic lymphadenopathy, lymphadenopathy in autoimmune diseases, posttransplant lymphoproliferative disorders, and X-linked lymphoproliferative disorder. The relationship to Epstein-Barr virus (EBV) and human herpsesvirus-8 (HHV-8) is discussed, and molecular diagnostic assays and principles for obtaining proper diagnostic evaluation are emphasized.

In Section II, Dr. Armitage presents a practical approach to the management of Castleman's disease. The discussion includes the importance of confirmation of the histological diagnosis and careful staging evaluation, therapeutic options, and the increased risks for infection and lymphoma. The appropriate roles of surgical excision, corticosteroids, and combination chemotherapy are addressed along with alternative strategies such as anti-interleukin-6 and bone marrow transplantation.

In Section III, Dr. Gross reviews the treatment of EBV-associated lymphoproliferative disorders in primary immunodeficiencies and in post-transplant patients. He gives an update on the recent molecular discoveries in X-linked lymphoproliferative disorder. Preliminary results of a phase II trial of low-dose cyclophosphamide in posttransplant lymphoproliferative disorders and the use of GM-CSF as preemptive therapy are presented.

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.

The molecular genetics of post-transplantation lymphoproliferative disorders

The post-transplantation lymphoproliferative disorders represent a significant clinical and diagnostic problem. However, these disorders also represent an important biological model for studying the development and progression of lymphoid neoplasia in immune deficiency. Accurate diagnosis and classification of these disorders requires correlative multiparametric analysis of the clinical behavior of the patient with the histopathological features, immunophenotype, clonal composition, and genetic alterations of the lymphoproliferative disorder. Such analyses should also assist in furthering our understanding of the pathogenesis of these disorders.

BCL-6 Gene Mutations in Posttransplantation Lymphoproliferative Disorders Predict Response to Therapy and Clinical Outcome

Posttransplantation lymphoproliferative disorders (PT-LPDs) represent a heterogeneous group of Epstein-Barr virus–associated lymphoid proliferations that arise in immunosuppressed transplant recipients. Some of these lesions regress after a reduction in immunosuppressive therapy, whereas some progress despite aggressive therapy. Morphological, immunophenotypic, and immunogenotypic criteria have not been useful in predicting clinical outcome. Although structural alterations in oncogenes and/or tumor suppressor genes identified in some PT-LPDs correlate with a poor clinical outcome, the presence of these alterations has not been a consistently useful predictor of lesion regression after reduction of immunosuppression. We examined 57 PT-LPD lesions obtained from 36 solid organ transplant recipients for the presence of mutations in the BCL-6 proto-oncogene using single-strand conformation polymorphism and sequence analysis, followed by correlation with histopathologic classification and clinical outcome, which was known in 33 patients. BCL-6 gene mutations were identified in 44% of the specimens and in 44% of the patients; none were identified in the cases classified as plasmacytic hyperplasia. However, mutations were present in 43% of the polymorphic lesions and 90% of the PT-LPDs diagnosed as non-Hodgkin's lymphoma or multiple myeloma. BCL-6 gene mutations predicted shorter survival and refractoriness to reduced immunosuppression and/or surgical excision. Our results suggest that the BCL-6 gene structure is a reliable indicator for the division of PT-LPDs into the biological categories of hyperplasia and malignant lymphoma, of which only the former can regress on immune reconstitution. The presence of BCL-6 gene mutations may be a useful clinical marker to determine whether reduction in immunosuppression should be attempted or more aggressive therapy should be instituted.

BCL-6 Gene Mutations in Posttransplantation Lymphoproliferative Disorders Predict Response to Therapy and Clinical Outcome

Posttransplantation lymphoproliferative disorders (PT-LPDs) represent a heterogeneous group of Epstein-Barr virus–associated lymphoid proliferations that arise in immunosuppressed transplant recipients. Some of these lesions regress after a reduction in immunosuppressive therapy, whereas some progress despite aggressive therapy. Morphological, immunophenotypic, and immunogenotypic criteria have not been useful in predicting clinical outcome. Although structural alterations in oncogenes and/or tumor suppressor genes identified in some PT-LPDs correlate with a poor clinical outcome, the presence of these alterations has not been a consistently useful predictor of lesion regression after reduction of immunosuppression. We examined 57 PT-LPD lesions obtained from 36 solid organ transplant recipients for the presence of mutations in the BCL-6 proto-oncogene using single-strand conformation polymorphism and sequence analysis, followed by correlation with histopathologic classification and clinical outcome, which was known in 33 patients. BCL-6 gene mutations were identified in 44% of the specimens and in 44% of the patients; none were identified in the cases classified as plasmacytic hyperplasia. However, mutations were present in 43% of the polymorphic lesions and 90% of the PT-LPDs diagnosed as non-Hodgkin's lymphoma or multiple myeloma. BCL-6 gene mutations predicted shorter survival and refractoriness to reduced immunosuppression and/or surgical excision. Our results suggest that the BCL-6 gene structure is a reliable indicator for the division of PT-LPDs into the biological categories of hyperplasia and malignant lymphoma, of which only the former can regress on immune reconstitution. The presence of BCL-6 gene mutations may be a useful clinical marker to determine whether reduction in immunosuppression should be attempted or more aggressive therapy should be instituted.

Epstein-Barr virus-related posttransplantation lymphoproliferative disorder involving pancreas allografts: histological differential diagnosis from acute allograft rejection

The clinical and pathological features of acute pancreas allograft rejection and involvement of the graft by posttransplantation lymphoproliferative disorders (PTLD) overlap. Because the treatment is diametrically opposite in these two types of lesions, an accurate diagnosis is essential. The histological features in pancreas allograft needle biopsy specimens (n=7) and pancreatectomies (n=4) from four patients with Epstein-Barr virus (EBV)-related PTLD were compared with the material from 14 patients who did not develop PTLD after 12 to 58 months of follow-up and whose biopsy specimens (n=10) and pancreatectomies (n=10) showed rejection-related heavy or atypical inflammatory infiltrates. Features typical of rejection included most (>75%) being of mixed small and large, activated-appearing T lymphocytes, a smaller component of mature plasma cells, and variable numbers of eosinophils. Cytologically atypical cells were always a minority (< 10%). The inflammation involved the septal spaces with proportional involvement of the exocrine tissue, veins, ducts, and arteries. The inflammation was particularly targeted against the acini and was associated with acinar cell damage. Features characteristic of PTLD were nodular and expansile infiltrates, composed of a significant proportion of atypical, plasmacytoid B cells (40% to 70% of the infiltrate); Reed-Sternberg-like cells were noted in two patients. The infiltrates involved the parenchyma randomly with no apparent affinity for the acinar tissue. Extensive infiltration of the peripancreatic soft tissues was common. Arterial walls were not involved in PTLD unless there was concurrent acute vascular rejection. Features identified in both conditions were foci of necrosis and infiltration of venous walls with associated endotheliitis. Samples with concurrent PTLD and acute rejection showed combinations of these features. In situ hybridization for EBER (Epstein-Barr-encoded RNAs) was positive only in the samples from patients with PTLD. Based on the assessment of morphological differences and the selective use of relatively simple ancillary techniques, PTLD can be correctly diagnosed even in small tissue samples such as needle biopsy specimens. An early diagnosis will lead to the appropriate treatment.

Clonal and morphological variation in a posttransplant lymphoproliferative disorder: evolution from clonal T-cell to clonal B-cell predominance

The majority of posttransplant lymphoproliferative disorders (PTLD) are Epstein-Barr virus (EBV)-associated and of B-cell origin. A much smaller proportion of PTLD are of T-cell origin. We report the clinical, morphological, immunophenotypic, and genotypic results of a unique PTLD, initially diagnosed as immune mediated thrombocytopenia (ITP), which at presentation was predominantly an anaplastic appearing EBV-associated T-cell PTLD and, after reduction in immunosuppression and the administration of antiviral agents, predominantly an EBV-associated plasma cell rich B-cell PTLD. Subsequent chemotherapy resulted in a complete remission. This case has both practical and biological implications. It highlights how PTLD may be misdiagnosed as other entities, how biclonal cases can have different morphological appearances and include both B- and T-cell clones, how PTLD can evolve over time possibly related to immune reconstitution, and why PTLD should be rebiopsied when the disease does not respond to decreased immunosuppression or recurs.

Visualization of human herpesvirus type 8 in Kaposi's sarcoma by light and transmission electron microscopy

BACKGROUND

Human herpesvirus type 8 (HHV-8) has been associated with Kaposi's sarcoma, body cavity-based lymphoma (BCBL), and multicentric Castleman's disease through DNA, in situ hybridization, and serologic studies. HHV-8 has been visualized only in HHV-8-positive/Epstein-Barr virus (EBV)-negative/ cytomegalovirus (CMV)-negative BCBL cell lines, but not in HHV-8-positive/EBV-negative/ CMV-negative Kaposi's sarcoma lesions.

DESIGN

Kaposi's sarcoma of the skin, lymph node, and spleen from three patients with AIDS were analysed for HHV-8, EBV and CMV DNA by polymerase chain reaction (PCR), for HHV-8 RNA (Tl.1 riboprobe) by in situ hybridization (ISH), for viral inclusions by light microscopy, and for herpesviruses by transmission electron microscopy (TEM). Sections were also labeled with Tl.1 counterstained with CD34, an endothelial cell marker.

RESULTS

The skin lesion was DNA PCR-positive for HHV-8 and CMV (nested, but not single PCR), the lymph node was positive for HHV-8 and EBV, and the spleen was positive for only HHV-8. TEM revealed infection by a virus displaying the typical morphology and cytopathicity of herpesviruses. Hexagonal nucleocapsids and mature enveloped virions were present in vasoformative spindle cells and mononuclear cells, often resembling lymphocytes. Extrapolating from TEM to standard light microscopy on hematoxylin and eosin-stained paraffin sections, eosinophilic, targetoid intranuclear inclusions were identified within spindle cells which often lined vascular lumina. The Tl.1-riboprobe labeled CD34+ spindle cells containing intranuclear inclusions, as well as mononuclear cells within Kaposi's sarcoma and residual lymphoid tissue.

CONCLUSION

The herpesvirus visualized in Kaposi's sarcoma lesions has morphologic and cytopathic features typical of human herpesviruses, productively infects vasoformative spindle cells and mononuclear cells, and is consistent with HHV-8. It can also form intranuclear inclusions that are identifiable by light microscopy in hematoxylin and eosin sections and by ISH.

Hodgkin's disease following solid organ transplantation

BACKGROUND

The incidence of second malignancies is markedly increased following transplantation of solid organs. However, the development of Hodgkin's disease has been described relatively infrequently in this setting, and there is little clinical information on these patients and few details on management.

PATIENTS AND METHODS

We have reviewed the pathologic specimens and clinical history of four patients who developed Hodgkin's disease following transplantation of solid organs.

RESULTS

Hodgkin's disease appeared 26-68 months following transplantation of the kidney (2 cases), liver, and heart. Three cases demonstrated evidence of Epstein-Barr virus (EBV) in Reed-Sternberg cells. One case appears to have arisen after a previous EBV-driven polymorphous lymphoproliferation. Hodgkin's disease was localized in three cases and disseminated in one. All patients achieved remission with standard therapy and continue in remission between 9 and 61 months after therapy. Graft function was preserved in all patients.

CONCLUSION

Hodgkin's disease occurring in the post-transplantation period should probably be treated like Hodgkin's disease in non-immunosuppressed patients. Prolonged disease-free survival is possible and function of the transplanted organ can be preserved.