Blastic/blastoid transformation of follicular lymphoma: immunohistologic and molecular analyses of five cases

Non-Hodgkin lymphoma mimicking acute leukemia: a report of six cases and review of the literature

Aggressive subtypes of non-Hodgkin lymphoma may uncommonly be referred to clinical oncologists for treatment of acute leukemia, due to an elevated or rapidly rising white blood cell count (WBC), with circulating neoplastic cells that morphologically resemble leukemic blasts seen in acute myeloid or lymphoblastic leukemia. We describe six cases of non-Hodgkin lymphoma that mimicked acute leukemia and were identified in the pathology records of the Brigham and Women's Hospital. The patients were older adults (mean age 70 years), who presented with leukocytosis (mean 79.7 × 10⁹/L) with circulating neoplastic cells (mean 57%), which mimicked leukemic blasts, thrombocytopenia, and anemia (4/6 patients). In each case, immunophenotypic analysis identified a population of mature B cells or mature T cells. We identified 15 additional cases of non-Hodgkin lymphoma in the literature that mimicked acute leukemia; considering all 21 cases, 11 had an appearance of acute lymphoblastic leukemia, 4 had an appearance of acute monocytic leukemia, and 6 had an appearance of acute leukemia unable to be further categorized. In general, patients exhibited poor overall survival. These cases illustrate the importance of comprehensive immunophenotypic analysis in the initial evaluation of hematolymphoid neoplasms, and that occasional cases of non-Hodgkin lymphomas can resemble acute leukemia at initial presentation.

The Biological Basis of Histologic Transformation

Histologic transformation of follicular lymphoma remains the leading cause of follicular lymphoma-related mortality in the rituximab era. Both the diverse timing of transformation and heterogeneity in associated genomic events suggest that histologic transformation may itself comprise distinct disease entities. Successive indolent and transformation episodes occur by divergent clonal evolution from an inferred common progenitor cell, representing a potential therapeutic target. Existing biological knowledge largely pre-dates anti-CD20 therapy, and further prospective validation is essential. Inclusion of transformation cases in clinical trials incorporating biomarker discovery, and an integrated understanding of the genetic and microenvironmental factors underpinning transformation, may unearth renewed clinical opportunities.

[The role of translocations involving c-MYC/8q24, BCL2/18q21 and/or BCL6/3q27 genes in patients with follicular lymphoma. Retrospective analysis of single - centre data]

Aim of the issue was to compare clinical characteristics and treatment results of patients with follicular lymphoma (FL) with translocations involving loci of c-MYC/8q24, BCL2/18q21 and/or BCL6/3q27 genes and patients with high - grade B-cell lymphoma [High - grade B-cell lymphoma (HGBL), double - hit (DH)]. Materials and methods. Since 2004 to 2017 years in National Research Center for Hematology 12 patients with high - grade B-cell lymphoma double - hit (HGBL DH) and 6 FL patients with translocations involving c-MYC and BCL2 and/or BCL6 had been treated. We performed a comparative analysis of clinical characterisctics in both groups. As primary endpoints was assessed frequency of complete remission (CR) or progressive disease (PD); as secondary endpoints - overall (OS) and event - free survival (EFS). Results. 5 patients with HGBL DH had c-MYC/BCL6, 7 - c-MYC/BCL2 rearrangements; 2 patients with FL had c-MYC/BCL2, 3 - c-MYC/BCL6, 1 - c-MYC/BCL2/BCL6 rearrangements. FL was represented by grade 3A in 2, grade 3B - in 4 cases, 3 of them had large - cell transformation. In HGBL DH and FL patients had no significant differences in clinical characteristics. The majority of patients had a widespread tumour, increased LDH activity, high frequency of extranodal and bone marrow involvement. Ki-67 expression level was lower in patients with FL (p.

High-grade Transformation of Low-grade B-cell Lymphoma: Pathology and Molecular Pathogenesis

Patients with low-grade (clinically indolent) lymphomas are at risk to undergo transformation to high-grade (clinically aggressive) lymphoma, although transformation only occurs in a subset of patients. When transformation occurs it is a critical event that determines the course of disease and is associated with unfavorable patient outcomes. Accurate detection of transformation, predictive biomarkers, and identification of specific molecular pathways implicated in the pathobiology of transformation will facilitate personalized therapeutic approaches and underpin advances in clinical outcomes. In this article, we present an update of the clinical and pathologic diagnostic criteria for low-grade B-cell lymphoma transformation and discuss the molecular alterations involved in the pathogenesis of this biological phenomenon.

The heterogeneity of follicular lymphomas: from early development to transformation

Follicular lymphoma (FL) is a lymphoma composed of germinal center B cells, i.e., centroblasts and centrocytes, that almost always show at least a focal follicular growth pattern. Most cases have a characteristic CD5-, CD10+, BCL6+, and BCL2+ immunophenotype, and 85 % of cases exhibit the hallmark translocation t(14;18)(q32;q21) involving BCL2 and IGH. Although the typical clinicopathological findings of FL are well recognized, cases with unusual clinical, morphologic, immunophenotypic, and genetic features may pose problems in diagnosis and nomenclature. In the slide workshop organized by the European Association for Haematopathology (EAHP) and the Society for Hematopathology (SH) held in Istanbul, Turkey, unusual variants of FL were discussed based on the submitted cases, including early lesions, localized extranodal presentation, uncommon immunophenotype, rare genetic alterations, diffuse variant, and marginal zone differentiation. Interesting features such as blastoid morphology and unusual progression forms were presented, aiming to understand the genetic basis of transformation. In this report, novel findings and diagnostic challenges emerging from the submitted cases will be highlighted, and new terminologies for some of these lesions are proposed.

Lymphoblastic transformation of follicular lymphoma: a clinicopathologic and molecular analysis of 7 patients

Approximately 30% of patients with follicular lymphoma (FL) transform to a more aggressive malignancy, most commonly diffuse large B cell lymphoma. Rarely, FL transformation results in clinical findings, histology, and immunophenotype reminiscent of B-lymphoblastic leukemia/lymphoma. We report the largest series to date with detailed analysis of 7 such patients. Lymphoblastic transformation occurred on average 2 years after initial diagnosis of FL. Five patients had prior intensive chemotherapy. Two patients developed mature high-grade lymphoma, followed by the lymphoblastic transformation. FL had BCL2 gene rearrangement in 4 of 5 cases. High-grade transformation was accompanied by MYC gene rearrangement (5 of 5). Transformation was characterized by expression of TdT, loss of Bcl6, variable loss of immunoglobulin light chain, and persistence of Pax-5, Bcl2, and CD10. Whole-exome sequencing in 1 case revealed presence of several actionable mutations (CD79B, CCND3, CDK12). FL, aggressive mature B cell lymphoma, and lymphoblastic transformation were clonally related in 6 evaluable cases. After transformation, survival ranged from 1 to 14 months. Four patients died of disease, 2 were in remission after stem cell transplant, and 1 was alive with disease.

High-grade B cell lymphoma, unclassifiable, with blastoid features: an unusual morphological subgroup associated frequently with BCL2 and/or MYC gene rearrangements and a poor prognosis

AIMS

A subset of B cell lymphomas with blastoid features do not fit either as B lymphoblastic lymphoma/leukaemia or blastoid mantle cell lymphoma. Their classification is challenging, even with complete clinicopathological and genetic information. At a haematopathology workshop, experts had suggested the term 'high-grade B cell lymphoma, unclassifiable, with blastoid features', and recommended further studies.

METHODS AND RESULTS

We describe the clinicopathological, immunophenotypic and cytogenetic findings of 24 high-grade B cell lymphomas, unclassifiable, with blastoid features. Fifteen patients presented de novo and seven patients had a history of lymphoma. Twenty patients (83%) presented with nodal disease. All tumours expressed pan-B cell antigens and 17 (89%) of 19 tumours assessed had a germinal centre B cell immunophenotype. Ten (63%) of 16 tumours assessed by fluorescence in-situ hybridization (FISH) had MYC rearrangement, 13 of 18 (72%) carried IGH-BCL2 and nine of 15 (60%) had both (double-hit lymphoma). The median overall survival was 1.1 years. Using 2008 World Health Organization criteria, 15 cases were classified as B cell lymphoma, unclassifiable, with features intermediate between diffuse large B cell lymphoma (DLBCL) and Burkitt lymphoma, and nine as DLBCL, small centroblastic variant.

CONCLUSION

High-grade B cell lymphomas, unclassifiable, with blastoid features are clinically aggressive with poor survival. Most neoplasms have a germinal centre B cell phenotype. MYC rearrangements and IGH-BCL2 are common, and ~60% are double-hit lymphomas.

Lymphoplasmacytic lymphoma and other non-marginal zone lymphomas with plasmacytic differentiation

Small B-cell lymphomas with plasmacytic differentiation frequently present diagnostic challenges. Session 3 of the 2009 Society for Hematopathology/European Association for Haematopathology Workshop focused on lymphoplasmacytic lymphoma (LPL). The submitted cases illustrated classic examples of bone marrow-based and nodal LPL and cases with atypical features, including unusual phenotypes or involvement of extranodal sites. Several cases showed varying degrees of overlap with marginal zone lymphoma, and, as acknowledged in the 2008 World Health Organization classification, a definitive distinction between these 2 possibilities cannot always be established. Session 6 of the workshop focused on other non-marginal zone lymphomas that may display plasmacytic differentiation. This session highlights the wide variety of neoplasms that enter into the differential diagnosis of small B-cell lymphomas with plasmacytic differentiation and demonstrates the use of clinical features and ancillary studies in establishing an appropriate diagnosis by 2008 World Health Organization criteria.

Transformation of follicular lymphoma

Histological transformation of follicular lymphoma (FL) to a more aggressive non-Hodgkin's lymphomas is a pivotal event in the natural history of FL and is associated with poor outcome. While commonly observed in clinical practice and despite multiple studies designed to address its pathogenesis, the biology of this process represents an enigma. In this chapter we present a state of the art review summarizing the definition of histologic transformation, its incidence, pathogenesis, clinical manifestations, treatment and outcome. Furthermore, we specifically emphasize gaps in our knowledge that should be addressed in future studies.

Transformation of follicular lymphoma to plasmablastic lymphoma with c-myc gene rearrangement

Follicular lymphoma (FL) is an indolent lymphoma that transforms to high-grade lymphoma, mostly diffuse large B-cell lymphoma, in about a third of patients. We present the first report of a case of FL that transformed to plasmablastic lymphoma (PBL). Clonal transformation of the FL to PBL was evidenced by identical IGH/BCL2 gene rearrangements and VDJ gene usage in rearranged IGH genes. IGH/ BCL2 translocation was retained in the PBL, which also acquired c-myc gene rearrangement. Genealogic analysis based on somatic hypermutation of the rearranged IGH genes of both FL and PBL suggests that transformation of the FL to PBL occurred most likely by divergent evolution from a common progenitor cell rather than direct evolution from the FL clone. Our study of this unusual case expands the histologic spectrum of FL transformation and increases our understanding of the pathogenetic mechanisms of transformation of indolent lymphomas to aggressive lymphomas.

B-cell lymphomas with concurrent IGH-BCL2 and MYC rearrangements are aggressive neoplasms with clinical and pathologic features distinct from Burkitt lymphoma and diffuse large B-cell lymphoma

B-cell lymphomas with concurrent IGH-BCL2 and MYC rearrangements, also known as "double-hit" lymphomas (DHL), are rare neoplasms characterized by highly aggressive clinical behavior, complex karyotypes, and a spectrum of pathologic features overlapping with Burkitt lymphoma (BL), diffuse large B-cell lymphoma (DLBCL) and B-lymphoblastic lymphoma/leukemia (B-LBL). The clinical and pathologic spectrum of this rare entity, including comparison to other high-grade B-cell neoplasms, has not been well defined. We conducted a retrospective analysis of clinical and pathologic features of 20 cases of DHL seen at our institution during a 5-year period. In addition, we carried out case-control comparisons of DHL with BL and International Prognostic Index (IPI)-matched DLBCL. The 11 men and 9 women had a median age of 63.5 years (range 32 to 91). Six patients had a history of grade 1 to 2 follicular lymphoma; review of the prior biopsy specimens in 2 of 5 cases revealed blastoid morphology. Eighteen patients had Ann Arbor stage 3 or 4 disease and all had elevated serum lactate dehydrogenase (LDH) levels at presentation. Extranodal disease was present in 17/20 (85%), bone marrow involvement in 10/17 (59%) and central nervous system (CNS) disease in 5/11 (45%). Nineteen patients were treated with combination chemotherapy, of whom 18 received rituximab and 14 received CNS-directed therapy. Fourteen patients (70%) died within 8 months of diagnosis. Median overall survival in the DHL group (4.5 mo) was inferior to both BL (P=0.002) and IPI-matched DLBCL (P=0.04) control patients. Twelve DHL cases (60%) were classified as B-cell lymphoma, unclassifiable, with features intermediate between DLBCL and BL, 7 cases (35%) as DLBCL, not otherwise specified, and 1 case as B-LBL. Distinguishing features from BL included expression of Bcl2 (P<0.0001), Mum1/IRF4 (P=0.006), Ki-67 <95% (P<0.0001), and absence of EBV-EBER (P=0.006). DHL commonly contained the t(8;22) rather than the t(8;14) seen in most BL controls (P=0.001), and exhibited a higher number of chromosomal aberrations (P=0.0009). DHL is a high-grade B-cell neoplasm with a poor prognosis, resistance to multiagent chemotherapy, and clinical and pathologic features distinct from other high-grade B-cell neoplasms. Familiarity with the morphologic and immunophenotypic spectrum of DHL is important in directing testing to detect concurrent IGH-BCL2 and MYC rearrangements when a karyotype is unavailable. The aggressive clinical behavior and combination of genetic abnormalities seen in these cases may warrant categorization as a separate entity in future classifications and call for novel therapeutic approaches.

Diffuse blastoid B-cell lymphoma: a histologically aggressive variant of t(14;18)-negative follicular lymphoma

Among the diffuse lymphomas of B-cell origin, we have encountered one variant displaying blastoid features that morphologically mimic lymphoblastic lymphoma, the blastoid variant of mantle cell lymphoma, and the so-called blastoid transformation of follicular lymphoma. To better characterize this entity, we studied eight cases morphologically, immunohistochemically, and by fluorescence in situ hybridization (FISH) for cytogenetic abnormalities commonly associated with follicular lymphoma and B-cell lymphomas exhibiting high-grade histological features. All eight cases were presented as de novo neoplasms, and displayed an entirely diffuse (five cases) or only minimal follicular (three cases) growth pattern. The neoplastic lymphoid cells were of medium size with round nuclei, fine chromatin, inconspicuous nucleoli, and high mitotic rate; they expressed CD10, BCL6, and BCL2-a phenotype consistent with follicle center cell origin. A proportion of cases expressed MUM1. Their lack of TdT and CYCLIN D1 distinguished them from lymphoblastic lymphoma and the blastoid mantle cell lymphoma, respectively. The neoplastic lymphoid cells consistently expressed CD43 (seven of eight cases) and occasionally other T-cell-associated antigens, including CD5, CD7, CD8, and CD57. Although all cases overexpressed BCL2, t(14;18) was not detected in any of the five cases examined by FISH; instead, extra copies of chromosome 18 were found in four of five cases. Finally, other cytogenetic abnormalities, including structural abnormalities of BCL6 (allelic loss/gain, rearrangement), monosomy 7, del(13)(q14), and MYC allelic loss, were frequently detected. The combination of a B-cell CD10+ BCL6+ BCL2+ phenotype in the presence of structural abnormalities of BCL6 is consistent with a follicular center cell derivation for our cases. The lack of t(14;18) seen in our cases, although rare in most cases of follicular lymphoma, has been nevertheless reported in cases of follicular lymphoma with a predominantly diffuse growth pattern. The molecular pathogenesis, clinical manifestations, and prognostic significance of these lesions remain to be elucidated.

Prolymphocytoid transformation of follicular lymphoma with coexpression of CD5 and CD10

Histologic transformation of follicular lymphoma is usually to a diffuse large B-cell lymphoma. We present a rare example of a histologic transformation of follicular lymphoma manifested by prolymphocytoid morphology and an unusual immunophenotype characterized by coexpression of CD5 and CD10. The transformed prolymphocytoid lymphoma was positive for CD5 and CD10 antigens by both flow cytometry and immunohistochemistry. The case also expressed bcl-2 and bcl-6 proteins, and exhibited t(14;18), consistent with derivation from a pre-existing follicular lymphoma. Polymerase chain reaction analysis of the immunoglobulin kappa light chain genes derived from the follicular lymphoma and prolymphocytoid lymphoma showed identical rearranged bands, suggesting clonal identity of the two neoplasms. The basis for coexpression of CD5 and CD10 remains unclear. Because the preceding low-grade follicular lymphoma was positive only for CD10 and did not express CD5, CD5 expression appears to be an acquired phenomenon accompanying the process of histologic transformation in this particular case. Prolymphocytoid transformation, similar to other histologic forms of transformation of follicular lymphoma, appears to accompany clinical progression of disease.

Application of Immunohistochemistry in the Diagnosis of Non-Hodgkin and Hodgkin Lymphoma

Context.—Beginning with the immunologic classifications of Lukes and Collins and Kiel and culminating in the Revised European-American Lymphoma and World Health Organization classifications, the diagnosis of lymphoid tumors relies heavily on the determination of cell lineage, maturation, and function, based on antigen expression in addition to morphology and clinical features. Technologic advances in immunology, antibody production, genetic analysis, cloning, and the identification of new genes and proteins by microarray and proteomics have provided pathologists with many antibodies to use in routine diagnosis.

Objective.—To provide guidance to the practicing pathologist in the appropriate selection of an antibody panel for the diagnosis of lymphoma based on morphology and relevant clinical data and to avoid pitfalls in the interpretation of immunohistochemical data. Attention is given to some of the newer antibodies, particularly against transcription factors, that are diagnostically and prognostically useful.

Data Sources.—The information presented in this article is based on review of the literature using the OVID database (Ovid MEDLINE 1950 to present with daily update) and 20 years of experience in diagnostic hematopathology.

Conclusions.—Immunophenotyping is required for the diagnosis and classification of lymphoid malignancies. Many paraffin-reactive antibodies are available to the pathologist but most are not specific. To avoid diagnostic pitfalls, interpretation of marker studies must be based on a panel and knowledge of a particular antigen's expression in normal, reactive, and neoplastic conditions.

Nodal aggressive B-cell lymphomas: a diagnostic approach

The diffuse aggressive B-cell lymphomas, as recognised in the 2001 WHO classification, represent a clinically and biologically heterogeneous group of neoplasms that require very different therapeutic approaches and have very different outcomes. They should be diagnosed using a multiparameter approach that emphasises morphological and immunophenotypic studies, and in at least some cases, relies on cytogenetic and/or genotypic studies. Incorporation of clinical data may be important as well. There is also current interest in going beyond the basic diagnosis and providing pathological prognostic information when possible. Whereas the diagnosis of some cases will be relatively easy, the differential diagnosis in others is very difficult, with some cases in a grey zone between two different well defined categories.

Surface immunoglobulin positive lymphoblastic leukemia in adults; a genetic spectrum

Precursor B-lymphoblastic leukemia is typically surface immunoglobulin (sIg) negative. Although rare cases of sIg+ precursor lymphoblastic leukemia are recognized, sIg+ leukemia often represent leukemic phase of Burkitt lymphoma or other non-Hodgkin lymphoma such as blastic mantle cell lymphoma. This study reports four adults, two women (56 and 58 years old) and two men (35 and 41 years old) with lymphoblastic leukemia that displayed lambda, surface immunoglobulin restriction (sIg+). The leukemic cells were all dim CD45 positive with side scatter light characteristic of blasts. Two cases were positive with the blasts associated with antigens TdT and CD34. Genetic abnormalities were detected in all cases and in three cases included abnormalities commonly present in precursor lymphoblastic leukemia. Translocation (1;19) (q23;p13) was present in the first case. Deletion of the 3' region of the mixed lineage leukemia (MLL) gene at chromosome 11q23 as well as t(14;18) were detected in the second case. In the 3rd case, a BCR-ABL fusion gene was detected as part of a complex abnormal karyotype. Translocation (1;19)(q23;p13) was present in one case. Deletion of the 3' region of the mixed lineage leukemia (MLL) gene at chromosome 11q23 as well as t(14;18) were detected in one case. BCR-ABL fusion gene was detected as part of a complex abnormal karyotype in one case. These cases illustrate that lymphoblastic leukemias occurring in adults exhibit a morphologic, immunophenotypic as well as a genetic spectrum and represent either non-Hodgkin lymphoma or precursor lymphoblastic leukemia. A multi-parameter approach including flow cytometric and genetic studies is crucial in separating these cases.

Low histologic grade follicular lymphoma with high proliferation index: morphologic and clinical features

Histologic grading has been used as a guide for clinical management in follicular lymphoma (FL). Proliferation index (PI) of FL generally correlates with tumor grade; however, in cases of discordance, it is not clear whether histologic grade or PI correlates with clinical aggressiveness. To objectively evaluate these cases, we determined PI by Ki-67 immunostaining in 142 cases of FL (48 grade 1, 71 grade 2, and 23 grade 3). A total of 24 cases FL with low histologic grade but high PI (LG-HPI) were identified, a frequency of 18%. On histologic examination, LG-HPI FL often exhibited blastoid features. Patients with LG-HPI FL had inferior disease-specific survival but a higher 5-year disease-free rate than low-grade FL with concordantly low PI (LG-LPI). However, transformation to diffuse large B-cell lymphoma was uncommon in LG-HPI cases (1 of 19; 5%) as compared with LG-LPI cases (27 of 74; 36%). In conclusion, LG-HPI FL appears to be a subgroup of FL with clinical behavior more akin to grade 3 FL. We propose that these LG-HPI FL cases should be classified separately from cases of low histologic grade FL with concordantly low PI.

p53 alterations in sequential biopsies of Asian follicular lymphoma: a study of immunohistochemical staining pattern and gene mutations by PCR-SSCP in paraffin-embedded tissues

AIM

Tumour suppressor gene p53 is a common target in carcinogenesis, reported to be altered and functionally inactive in 70% of human cancers. Although p53 mutations are less commonly present in haematological malignancies when compared with other solid tumours, they have been reported in histological transformation of follicular lymphoma. We aimed to investigate the frequency of p53 gene alterations in paraffin-embedded tissue using commercially available PCR-SSCP, and to correlate the results with P53 protein expression by immunohistochemistry.

METHODS

Surgical samples from seven patients with a total of 17 sequential biopsies were retrieved for the study of p53 gene expression using immunohistochemical stain, and gene status by PCR-SSCP for exons 5-8. The tumours were graded according to the WHO classification criteria. P53 was distinctly over-expressed in five transformed higher grade biopsies, and all except one showed electrophoretic mobility shift in PCR-SSCP analysis. Sequencing analysis revealed single nucleotide substitutions in three of four of these high-grade transformed cases with band shift (75%), whereas some other studies reported a lower frequency of 25-30%, and mobility shift result was found to correlate with P53 expression. Lower grade tumours without P53 over-expression did not demonstrate band shift, and sequencing analysis did not reveal mutations.

CONCLUSIONS

We demonstrated the feasibility of adopting PCR-SSCP for screening of p53 mutations in archival tissue samples in this study, and there is a strong correlation of p53 gene over-expression and mutation events in high-grade transformed tumours.

Immunophenotypic and genotypic characterization of progression in follicular lymphomas

Progression of follicular lymphomas (FLs) is often accompanied by a spectrum of histologic changes and an aggressive clinical course. Although molecular alterations have been implicated in this event, the underlying factors are largely unknown. We studied the expression of selected tumor suppressor genes (P53 and retinoblastoma [RB]), oncogenes (MYC and BCL2), and a transferrin-receptor related protein (Trump) in sequential biopsies in 16 patients. Eleven patients progressed from grade I or II FL to aggressive B-cell lymphomas with diffuse morphology, whereas 5 patients presented with diffuse aggressive lymphomas and recurred with indolent lymphomas. Immunoreactivity for P53 correlated with higher histologic grade in lymphomas progressing from indolent to aggressive; however, only 1 patient who presented with aggressive lymphoma demonstrated a P53 gene mutation. Neither P53 immunoreactivity nor genotypic alterations correlated with presentation with an aggressive histology and relapse with FL. Growth fraction, as assessed by Ki-67 staining, and Trump expression correlated with histologic grade. Immunoreactivity for RB, BCL2, and MYC was seldom associated with progression. Eight of 9 cases tested exhibited identical immunoglobulin heavy and light chain rearrangements or identical BCL2 gene rearrangements in the sequential lymphomas. We conclude that P53 and Trump protein expression and proliferation activity correlate with histologic grade, but not with recurrence or progression of FL. Our results further indicate that progression of FL to diffuse aggressive lymphomas and presentation of an aggressive B-cell lymphoma followed by FL are clonally related.

Peripheral blood manifestations of lymphoma and solid tumors

Although the peripheral blood film has limited use in this age of technologic testing, most new tests are ancillary and cannot be interpreted accurately without examining the peripheral blood film. The peripheral smear plays a critical role in the diagnosis and management of many lymphoproliferative disorders, although playing more of a general function in nonlymphoid malignancies to evaluate cytopenias.

Precursor B-cell lymphoblastic lymphoma. A study of nine cases lacking blood and bone marrow involvement and review of the literature

We describe 9 cases of precursor B-cell lymphoblastic lymphoma (LYL) without evidence of marrow or blood involvement. Four patients had superficial nodal disease, 2 cutaneous involvement, and 1 each ovarian, retroperitoneal, or tonsillar primary tumor. Six patients had limited disease; 3 patients were stage III. Immunophenotyping revealed a terminal deoxynucleotidyl transferase (TdT)-positive, immature B-cell population with variable expression of CD10, CD20, and CD45. All patients are in complete clinical remission (median follow-up, 14 months). A literature review yielded 105 patients with a diagnosis of precursor B-cell LYL based on less than 25% marrow involvement. Of these, 64% were younger than 18 years. Skin, lymph nodes, and bone were the most common sites of disease. Mediastinal involvement was uncommon. TdT, CD19, CD79a, CD10, and HLA-DR were the most frequently expressed antigens, while CD45 and CD20 were expressed in only two thirds of the cases. Cytogenetic analysis showed additional 21q material as a recurring karyotypic abnormality. At a median follow-up of 26 months, 74% of patients were alive; the median survival was 19 months for patients dying of disease. Comparison with precursor B-cell acute lymphoblastic leukemia showed several overlapping features, although distinct differences were identified.

Chromosomal analyses of 52 cases of follicular lymphoma with t(14;18), including blastic/blastoid variant

We have identified 52 patients of follicular lymphoma (FL) with t(14;18)(q32;q21). Histologically, the lymphomas were placed into six groups according to their cellular composition and growth pattern. Chromosome analysis revealed that all cases but one had additional secondary chromosomal abnormalities. The most frequent numerical aberrations were gains of chromosomes 7 (38%), X (36%), 5 (15%), 12 (15%), 18/der(18)t(14;18) (25%), and 21 (15%). Structural abnormalities of chromosome 1 were seen in 19 tumors (36%) affecting both arms with breakpoints clustered at 1p36. Other structural abnormalities included partial deletions of 6q, 10q, and 13q. Breakpoint at 8q24 was seen in four cases. The chromosome aberrations were correlated with the morphological subtypes of follicular lymphoma. Gain of chromosome 7 appeared to be associated with follicular large cell lymphoma. The incidence of trisomy 5 and 12, and 13q- was higher in follicular lymphoma with aggressive histological features than in low-grade lymphoma. In addition, complexity of the karyotype and high degree of polyploidy increased with the grade. The most valuable cytogenetic markers in the t(14;18) lymphomas are those involving 8q24 which was found exclusively in the blastic/blastoid variant FL. Therefore, chromosome analysis in relation to histologic pattern of follicular lymphoma can provide additional information in predicting tumor evolution and transformation to a higher-grade malignancy.