Cellular kinetic and phenotypic heterogeneity in and among Burkitt's and Burkitt-like lymphomas

How our practice of histopathology, especially tumour pathology has changed in the last two decades: reflections from a major referral center in Pakistan

Continued advances in the field of histo-pathology (and cyto-pathology) over the past two decades have resulted in dramatic changes in the manner in which these disciplines are now practiced. This is especially true in the setting of a large university hospital where the role of pathologists as clinicians (diagnosticians), undergraduate and postgraduate educators, and researchers has evolved considerably. The world around us has changed significantly during this period bringing about a considerable change in our lifestyles and the way we live. This is the world of the internet and the world-wide web, the world of Google and Wikipedia, of Youtube and Facebook where anyone can obtain any information one desires at the push of a button. The practice of histo (and cyto) pathology has also evolved in line with these changes. For those practicing this discipline in a poor, developing country these changes have been breathtaking. This is an attempt to document these changes as experienced by histo (and cyto) pathologists practicing in the biggest center for Histopathology in Pakistan, a developing country in South Asia with a large (180 million) and ever growing population. The Section of Histopathology, Department of Pathology and Microbiology at the Aga Khan University Hospital (AKUH) in Karachi, Pakistan's largest city has since its inception in the mid-1980s transformed the way histopathology is practiced in Pakistan by incorporating modern methods and rescuing histopathology in Pakistan from the primitive and outdated groove in which it was stuck for decades. It set histopathology in Pakistan firmly on the path of modernity and change which are essential for better patient management and care through accurate and complete diagnosis and more recently prognostic and predictive information as well.

High-grade mature B-cell lymphoma with Burkitt-like morphology: results of a clinicopathological study of 72 Japanese patients

The aim of the present study was to estimate optimum chemotherapeutic regimens for high-grade mature B-cell lymphoma cases with Burkitt-like morphology (Burkitt's lymphoma [BL]/Burkitt-like lymphoma [BLL]) patients. We analyzed 72 BL/BLL, including 36 with the c-myc translocation (molecular BL [mBL]), 20 without it (mBL-like), and 16 in whom we were uncertain regarding the existence of the c-myc translocation, and compared them with 182 diffuse large B-cell lymphoma (DLBCL) cases. On clinical and immunophenotypic analysis, the typical BL immunophenotype (CD10 positive, bcl-2 negative, and Ki-67 index >or=95%) was noted in 23 (66%) and 11 (55%) of the 35 mBL and 20 mBL-like patients, respectively. The presence of the c-myc translocation and typical immunophenotype in BL did not affect the overall survival of BL/BLL. There were no significant differences between the overall survival of DLBCL (45%) and BL/BLL (50%, P = 0.85). However, the overall survival of BL/BLL patients who received cyclophosphamide, doxorubicin, vincristine, and prednisolone-related therapy (22%) was significantly lower than that of DLBCL patients (P = 0.01). In contrast, the overall survival of BL/BLL patients who received aggressive short-term chemotherapy (75%) was better than that of the patients who received cyclophosphamide, doxorubicin, vincristine, and prednisolone therapy (P < 0.01). The finding was confirmed by multivariate analysis (hazard ratio 4.4; confidence interval 2.0-9.7; P = 0.0003). We concluded that aggressive short-term chemotherapy improves survival in BL/BLL, regardless of its genetic and immunophenotypic features.

Gene-expression analysis identifies novel RBL2/p130 target genes in endemic Burkitt lymphoma cell lines and primary tumors

Burkitt lymphoma (BL) is a B-cell tumor whose characteristic gene aberration is the translocation t(8;14), which determines c-myc overexpression. Several genetic and epigenetic alterations other than c-myc overexpression have also been described in BL. It has been demonstrated that the RBL2/p130 gene, a member of the retinoblastoma family (pRbs), is mutated in BL cell lines and primary tumors. The aim of this study was to investigate the biologic effect of RBL2/p130 in BL cells and its possible role in lymphomagenesis. Therefore, we reintroduced a functional RBL2/p130 in BL cell lines where this gene was mutated. Our results demonstrated that RBL2/p130-transfected cells regain growth control. This suggests that RBL2/p130 may control the expression of several genes, which may be important for cell growth and viability. Gene-expression analysis revealed a modulation of several genes, including CGRRF1, RGS1, BTG1, TIA1, and PCDHA2, upon RBL2/p130 reintroduction. We then monitored their expression in primary tumors of endemic BL as well, demonstrating that their expression resembled those of the BL cell lines. In conclusion, these data suggest that, as RBL2/p130 modulates the expression of target genes, which are important for cell growth and viability, its inactivation may be relevant for the occurrence of BL.

Mature B-cell lymphoma in children and adolescents: International group pathologist consensus correlates with histology technical quality

In pediatric mature B-cell non-Hodgkin lymphoma, international pathologist diagnostic agreement was previously evaluated using the Revised European-American Lymphoma Classification. Surgical biopsy histology technical quality (HTQ) is variable and may affect diagnostic accuracy. This study evaluated diagnostic agreement correlated with HTQ. Surgical biopsies obtained from international protocol FAB LMB96 Treatment of Mature B-Cell Lymphoma/Leukemia for Burkitt lymphoma (BL), diffuse large B-cell lymphoma (DLBCL), and high-grade B-cell lymphoma Burkitt-like (BLL), were independently reviewed by hematopathologists from 3 national groups (Children's Cancer Group, Société Française d'Oncologie Pédiatrique, and United Kingdom Children's Cancer Study Group) to determine each national diagnosis and a final diagnosis. HTQ grades for microscopic tissue sections included: good; medium; low; inconclusive. Final diagnoses in 187 cases included: BL 87 (47%); BLL 20 (11%); DLBCL 64 (34%); other 16 (9%). HTQ grades included: good 10 (5%); medium 100 (54%); low 75 (40%); inconclusive 2 (1%). The rate of uniform agreement between the national diagnoses was significantly higher with good or medium HTQ (62%) than with low HTQ (33%) (P = 0.001). In conclusion, in pediatric mature B-cell non-Hodgkin lymphoma, international pathologist diagnostic agreement is significantly higher in surgical biopsies with better HTQ. Poor HTQ may adversely impact diagnostic ability and affect prognosis and therapeutic management when different treatment regimens are employed for DLBCL versus BL/BLL.

IL-10 can induce the expression of EBV-encoded latent membrane protein-1 (LMP-1) in the absence of EBNA-2 in B lymphocytes and in Burkitt lymphoma- and NK lymphoma-derived cell lines

EBV-positive nasopharyngeal carcinoma and Hodgkin, T, and natural killer (NK) lymphomas express EBNA-1 and the latent membrane proteins (LMP1-2; type II latency). In contrast to type III EBV-transformed lymphoblastoid cell lines, in these cells the LMPs are expressed in the absence of EBNA-2. We have previously reported that exposure to CD40 ligand and IL-4 could induce LMP-1 in an in vitro EBV-infected Hodgkin lymphoma-derived cell line, which expressed only EBNA-1. We show now that both human and EBV-encoded IL-10 can induce LMP-1 in the absence of EBNA-2 in the Daudi, P3HR1, and other BL cell lines. Interestingly, induction of LMP-1 was not accompanied by the downregulation of BCL-6. IL-10 could also induce LMP-1 in the conditional lymphoblastoid cell line ER/EB2-5 where EBNA-2 was downregulated in the absence of estrogen. Moreover, IL-10 could induce the expression of LMP-1 in tonsillar B cells infected with the nontransforming, EBNA-2-deficient EBV strain P3HR1 and enhance LMP-1 expression in 2 EBV-positive NK lymphoma lines. The demonstration that IL-10 can induce the expression of LMP-1 in an EBNA-2-independent manner shows that the major transforming EBV gene LMP-1 can be induced by extracellular signals in lymphoid cells, and IL-10 might contribute to the establishment of type II EBV latency.

Immunoglobulin gene analysis reveals 2 distinct cells of origin for EBV-positive and EBV-negative Burkitt lymphomas

The normal counterpart of the neoplastic B cells in Burkitt lymphoma (BL) is still unclear. Based on immunoglobulin gene rearrangement studies, some authors suggest an origin from germinal center cells and others from memory B cells. However, most of these studies rely on cell lines or on a small series of cases. To help clarify the cell of origin of BL, semi-nested polymerase chain reaction (PCR) was performed to amplify the VDJ rearrangements of the immunoglobulin heavy chain (VH) genes, and the resultant amplificates were sequenced for comparison with known germline VH segments. The results of this approach revealed that all cases (15 endemic BL [eBL], 10 sporadic BL [sBL], and 6 AIDS-related BL) harbor mutated VH genes, with different mutation ranges among the 3 types of BL. The eBL and AIDS-related forms showed considerably higher mutation rates than the sBL form (5.1%, 5.4%, and 1.5%, respectively). The mutations in eBL and AIDS-related BL also showed signs of antigen selection, whereas no signs of antigen selection were found in sBL. Finally, after subcloning the amplificates, sequence analysis revealed no signs of ongoing mutations in any of the cases analyzed. Given that one of the main differences between eBL and AIDS-related BL on the one hand and sBL on the other hand is the association with Epstein-Barr virus (EBV), we compared EBV-positive and EBV-negative BLs independently of their geographic origin and HIV status. The differences in the number of somatic mutations and antigen selection were even more evident when this approach was used. According to our molecular results, it appears that EBV-positive and EBV-negative BL may originate from 2 distinct subsets of B cells, pointing to a particular role for the germinal-center reaction in the pathogenesis of these tumors. The different types of C-MYC translocation reported in BL may also be related to the different stages of B-cell maturation.

Differential Expression of WT1 Gene Product in Non-Hodgkin Lymphomas

The tumor suppressor gene wt1 (Wilms tumor 1) encodes a zinc finger transcription factor reported to be expressed in many tumors, including mesotheliomas, carcinomas, and acute leukemias. However, WT1 expression in non-Hodgkin lymphomas (NHLs) has not been studied. The authors assessed for WT1 expression in six lymphoma/leukemia cell lines using Western blot methods after subcellular fractionation. We also assessed for WT1 expression in 167 NHLs using immunohistochemical methods. The B-cell NHLs analyzed were 18 diffuse large B-cell lymphomas, 13 marginal zone B-cell lymphomas, 9 small lymphocytic lymphomas, (DLBCLs), 8 follicular lymphomas, 6 mantle cell lymphomas, 5 Burkitt lymphomas, 3 lymphoplasmacytic lymphomas, and 2 B-cell lymphoblastic lymphomas. The T-cell NHLs analyzed were 43 anaplastic large cell lymphomas (ALCLs), 26 peripheral T-cell lymphomas unspecified, 13 angioimmunoblastic T-cell lymphomas, 6 cutaneous ALCLs, 6 cases of mycosis fungoides, 5 extranodal NK/T-cell lymphomas of nasal type, and 4 T-cell lymphoblastic lymphomas. WT1 levels were higher in cytoplasmic extracts than in nuclear extracts of the Karpas 299 and SU-DHL-1 lymphoma cell lines but were higher in nuclear extracts than in the cytoplasmic extracts of the Jurkat, HH, U-937, and K562 leukemia cell lines. In NHLs, WT1 was positive in 4 of 5 (80%) Burkitt lymphomas, 9 of 12 (75%) ALK-positive ALCLs, 3 of 6 (50%) lymphoblastic lymphomas (2 of 4 T-cell, 1 of 2 B-cell), 14 of 31 (45%) ALK-negative ALCLs, 6 of 18 (33%) DLBCLs, and 1 of 6 (17%) cutaneous ALCLs. WT1 was negative in all other NHLs tested. WT1 immunoreactivity was primarily cytoplasmic in all positive NHLs except T-cell lymphoblastic lymphoma. In conclusion, WT1 protein is frequently detected in the cytoplasm of a subset of high-grade NHLs.

An anti-apoptotic role for galectin-3 in diffuse large B-cell lymphomas

Increased resistance to apoptosis promotes lymphomagenesis with aberrant expression of cell survival proteins such as BCL-2 and c-MYC occurring in distinct lymphoma subtypes. Galectin-3 is an anti-apoptotic protein that protects T cells, macrophages, and breast carcinoma cells from death triggered by a variety of agents. We have found high levels of galectin-3 protein expression in a subset of B-cell neoplasms including diffuse large B-cell lymphoma (DLBCL), primary effusion lymphoma (PEL), and multiple myeloma (MM), in both cell lines and patient samples. However, we failed to detect galectin-3 in Burkitt lymphoma (BL), follicular lymphoma (FL), marginal zone lymphoma (MZL), MALT lymphoma or B-small lymphocytic lymphoma (B-SLL) cell lines or patient samples. To determine whether galectin-3 expression protects B cells from apoptosis, galectin-3-negative BL cells were transfected with a galectin-3 expressing plasmid, which resulted in markedly increased resistance to anti-Fas-induced cell death. In contrast, galectin-3-positive PEL cells transfected with an amino-terminal truncated galectin-3 vector showed increased sensitivity to anti-Fas induced apoptosis. During normal B-cell development, galectin-3 expression was lowest in germinal center and plasma B cells, from which DLBCL, PEL, and MM derive, and highest in long-lived naïve and memory B cells. This pattern of expression suggests that aberrantly increased galectin-3 levels in specific B-cell populations may yield a protective advantage during transformation and/or progression of certain B-cell neoplasms.

Cell kinetics and cell cycle regulation in lymphomas

The proliferative indices of non-Hodgkin's lymphomas are useful prognostic indicators and provide information independent of other histological and clinical variables. However, proliferative indices alone do not suffice to characterise cell growth. A high cell production rate may be compensated, almost or fully, by a high cell deletion rate. A re-evaluation of parameters of cell kinetics in view of our increasing knowledge of the molecular pathways of cell cycle control may provide more prognostic information for the management of patients with malignant lymphomas.

Pediatric non-Hodgkin's lymphoma: clinical and biologic prognostic factors and risk allocation

The use of effective combination chemotherapy for all stages and subtypes of non-Hodgkin"s lymphoma (NHL) in children has resulted in a striking improvement in cure rates. Event-free survival now ranges from 70% to 90%, depending on the stage of disease and the NHL subtype. Risk-adapted therapy has resulted in a dramatic improvement in outcome for high-risk patients, at the cost of significantly increased short-term toxicity, and a reduction of therapy and toxicity for the lower-risk patient, while maintaining the excellent cure rate. Successful risk allocation of patients is dependent on the identification and continual validation of prognostic factors. The specific treatment protocol is the single most important factor predicting outcome today. Traditional prognostic factors such as stage and tumor burden are useful in selecting the intensity and length of therapy, rather than as a major indicator of likelihood of survival. In order to further improve cure rates and decrease toxicity, new biologic prognosticators need to be found and validated. Some promising avenues for study appear to be the presence or absence of adhesion molecules and of aberrant proteins that are specific to subtypes of lymphomas, such as soluble CD30 and anaplastic lymphoma kinase (ALK), the molecular classification of lymphomas on the basis of gene expression, and the evaluation of biologic markers for measuring early response to therapy.

Proteins encoded by genes involved in chromosomal alterations in lymphoma and leukemia: clinical value of their detection by immunocytochemistry

Acquired chromosomal anomalies (most commonly translocations) in lymphoma and leukemia usually result in either activation of a quiescent gene (by means of immunoglobulin or T-cell-receptor promotors) and expression of an intact protein product, or creation of a fusion gene encoding a chimeric protein. This review summarizes current immunocytochemical studies of these 2 categories of oncogenic protein, with emphasis on the clinical relevance of their detection in diagnostic samples. Among the quiescent genes activated by rearrangement, expression of cyclin D1 (due to rearrangement of the CCND1 [BCL-1] gene) is a near-specific marker of t(11;14) in mantle cell lymphoma; BCL-2 expression distinguishes follicular lymphoma cells from their nonneoplastic counterparts in reactive germinal centers and appears to be an independent prognostic marker in diffuse large cell lymphoma; and TAL-1 (SCL) expression identifies T-cell acute lymphoblastic neoplasms in which this gene is activated. The protein products of other genes activated by chromosomal rearrangement have a role as markers of either lineage (eg, PAX-5 [B-cell-specific activator protein] for B cells, including B-lymphoblastic neoplasms), or maturation stage (eg, BCL-6 for germinal-center and activated B cells and MUM-1/IRF4 for plasma cells). Currently, no hybrid protein encoded by fusion genes is reliably detectable by antibodies recognizing unique junctional epitopes (ie, epitopes absent from the wild-type constituent proteins). Nevertheless, staining for promyelocytic leukemia (PML) protein will detect acute PML with t(15;17) because the microspeckled nuclear labeling pattern for PML-RARalpha is highly distinctive. Similarly, antibodies to the anaplastic lymphoma kinase (ALK) tyrosine kinase are valuable (because wild-type ALK is not found in normal lymphoid tissue) in detecting neoplasms (CD30-positive large T-cell lymphomas) with t(2;5) or its variants. Thus, immunocytochemical detection of the products of many rearranged genes in lymphoma and leukemia can be clinically informative and provide information on cellular and subcellular protein expression that cannot be inferred from studies based on messenger RNA.

Work-up and diagnosis of pediatric non-Hodgkin's lymphomas

Non-Hodgkin's lymphomas (NHL) in children and adolescents represent about 10% of childhood cancers. Although the types of NHL commonly seen in this population are relatively limited to lymphoblastic lymphomas, Burkitt's and Burkitt-like lymphomas, and large cell lymphomas, correct diagnosis and classification are essential for optimal therapy. Careful handling of pathologic specimens, along with collection of proper materials for ancillary studies such as immunophenotyping, cytogenetics, or molecular studies, will aid the pathologist in reaching a correct diagnosis. Specific morphologic, immunophenotypic, and genetic features of the commonly seen types of pediatric NHL are described.

Incidence and pathology of primary brain lymphoma in Hong Kong Chinese patients

Primary brain lymphoma (PBL) is an uncommon extranodal lymphoma. Its incidence is rapidly increasing in both immunocompromised and immunocompetent patients in Western countries. Eighteen cases of PBL were identified during a 16-year period among HIV negative patients in Queen Mary Hospital, Hong Kong. One case of post-transplantation lymphoproliferative disease (PTLD) was positive for Epstein Barr virus (EBV) encoded RNA (EBER) by in situ hybridization. All the remaining 17 immunocompetent cases were classified as diffuse large B-cell lymphoma, except for one case of Burkitt's lymphoma. EBER expression was negative in all 13 cases tested. Immunostaining for bcl-2 and bcl-6 was positive in 8/11 and 6/11 cases tested, with heterogeneous combination of expression and intensity. The incidence rate of PBL in immunocompetent patients was stable at 1.03 per million per year. The incidence of PBL in post transplantation (0.16%) and HIV related setting (0.29%) is also low in Chinese. PBL in Chinese patients is almost uniformly represented by EBV negative, diffuse large B-cell lymphoma, confined to the brain. However, the molecular pathogenesis may be heterogeneous.

Genetic alterations of the retinoblastoma-related gene RB2/p130 identify different pathogenetic mechanisms in and among Burkitt's lymphoma subtypes

Alterations of cell cycle-associated genes probably contribute to the pathogenesis of Burkitt's Lymphoma (BL), in addition to c-myc translocation. Mutations disrupting the nuclear localization signal of the retinoblastoma-related gene RB2/p130 have been documented recently in BL cell lines and primary tumors. Given the importance of the RB2/p130 gene in controlling cell growth, mutations of this gene may result in uncontrolled cell proliferation. We tested the expression and genomic organization of the RB2/p130 gene in relation to the proliferative features of a series of BL samples collected from the endemic and sporadic regions, regardless of whether the samples were acquired immune deficiency syndrome (AIDS)-related. The expression of the Rb2/p130, p107, and cell proliferation-related proteins (cyclin A and B) was determined by immunohistochemistry. The structures of exons 19 through 22 of the RB2/p130 gene, encoding for the B domain and C terminus, were analyzed by polymerase chain reaction (PCR) analysis and single-strand conformation polymorphism (SSCP) technique. The direct PCR products were sequenced to identify the actual mutations. Our results suggest that BL is composed of a mixture of molecular types with distinct genetic and phenotypic patterns, probably resulting from different pathogenetic mechanisms. In endemic BL, the RB2/p130 gene is mutated in most of the cases, and the protein is restricted to the cytoplasm. In AIDS-related BL, high levels of nuclear expression of the wild-type pRb2/p130, p107, and cell proliferation-related proteins were detected. This finding is in line with the molecular mechanisms observed in virus-linked oncogenesis. Sporadic BLs were mainly characterized by the low nuclear values of the wild-type pRb2/p130 and, conversely, the high values of p107. The increased cell proliferation due to different alterations of cell growth control by Rb-related proteins may be the first step in lymphomagenesis, during which additional genetic changes, including missense mutations of c-myc, may subsequently occur.

Mature B-cell lymphoma/leukemia in children and adolescents: intergroup pathologist consensus with the revised European-American Lymphoma Classification

BACKGROUND

The Revised European-American Lymphoma (R.E.A.L.) Classification criteria were evaluated in the international protocol FAB LMB 96 Treatment of Mature B-cell Lymphoma/Leukemia: A SFOP LMB 96/CCG-5961/UKCCSG NHL 9600 Cooperative Study. This includes B-lineage lymphomas: Burkitt's lymphoma (including ALL-L3); high-grade B-cell lymphoma, Burkitt-like; diffuse large B-cell lymphoma (excluding anaplastic large cell Ki-1 lymphoma).

PATIENTS AND METHODS

Cases were independently reviewed by eight hematopathologists from the three cooperative national groups (two SFOP, two CCG, four UKCCSG), without prior discussion of classification criteria or guidelines for case rejection. Consensus diagnosis was determined by each national cooperative group, and final consensus diagnosis established when at least two national consensus diagnoses were in agreement, or following group agreement at a multiheaded microscope.

RESULTS

Two hundred eight cases were reviewed, with final consensus diagnosis established in two hundred three. The percent agreement of each group's national consensus diagnosis with final consensus diagnosis was 86%, 86% and 71%. The percent agreement of the group's national consensus diagnosis with final consensus diagnosis for Burkitt's and diffuse large B-cell lymphoma were 88% and 80%, respectively, but only 42% for Burkitt-like lymphoma.

CONCLUSIONS

International panel review of mature B-cell lymphoma/leukemia in children and adolescents highlighted difficulties in subclassification, particularly with Burkitt-like, which is a 'provisional entity' in the R.E.A.L. Classification. The absence of previous discussion of classification and guidelines for case rejection may in part explain the discrepancy between pathologists. These results underline that morphology may need to be complemented by other studies, such as molecular genetic and cytogenetics, to discriminate between the mature B-cell lymphomas.

HIV-associated malignant lymphomas in Kenya (Equatorial Africa)

The clinical and pathological features of acquired immune deficiency syndrome (AIDS)-related lymphomas, including their relationship with other viruses, such as Epstein-Barr virus (EBV) and human herpes virus-8 (HHV8), have been the subject of several studies from North America and Europe. No consistent data have been reported in Africa, where AIDS runs an epidemiological and clinical course different from that observed in Western countries. We retrospectively evaluated the presence of human immunodeficiency virus (HIV), HHV8, and EBV in 146 cases of malignant lymphomas collected in Kenya (Equatorial Africa), with the use of polymerase chain reaction (PCR) and in situ hybridization (ISH). The PCR technique confirmed HIV infection in 16 HIV-seropositive subjects (11%) and showed the presence of HIV sequences in five additional cases (3%) in which the occurrence of lymphoma was the only clinical manifestation. Our findings suggest that AIDS-related lymphomas are not pathogenetically homogenous, and different mechanisms may contribute to lymphomagenesis in these severely immunocompromised patients. In our series, no association of Hodgkin's disease (HD) with HIV infection could be shown. Among non-HIV-related lymphomas, EBV was present in 94% of Burkitt lymphoma (BL) occurring in patients younger than 15 years of age, in 87% of HD independently of age, sex, and histological types, in 60% of anaplastic large cell lymphoma (ALCL), and to a lesser extent (13%) in large B-cell lymphoma (LBCL) cases. Only one tumor, a case of HD, showed HHV8 by PCR.

What is Burkitt's lymphoma?

Burkitt's lymphoma (BL) has been defined on the basis of its characteristic cytomorphology. Although histologically identical, endemic BL and sporadic BL are distinct clinico-anatomical entities. Their morphological identity probably relates to similar chromosomal translocations in both tumours, resulting in c-myc de-regulation and consequent unrestrained proliferation without differentiation. Similar gene rearrangements are found in a proportion of AIDS-related lymphomas that are predominantly extranodal and have the cytomorphology of BL. The term "Burkitt-like lymphoma" (BLL) has been applied to a group of high-grade B-cell lymphomas that appear morphologically intermediate between BL and centroblastic/immunoblastic lymphomas, as detailed in an accompanying paper in this issue. These tumours do not usually show c-myc gene rearrangements. The association of Burkitt's name with such a disparate group of tumours is confusing and new terminology for sporadic BL, AIDS-related BL and BLL is desirable. It is important that clinico-anatomical features, as well as cytomorphology, should be taken into account in the diagnosis of endemic BL. The origin of a case from tropical Africa does not, in itself, imply that it is endemic BL, even more since the AIDS epidemic in that continent.