Flow cytometric immunophenotyping of non-Hodgkin's lymphomas and related disorders

A quality improvement assessment of multiple, concurrent flow cytometry analyses at a tertiary care center

INTRODUCTION

The utility of flow cytometry (FC) in diagnosis and staging of hematologic malignancy is controversial. Often, multiple specimens from the same patient are processed concurrently for FC analyses, alongside tissue for histomorphologic diagnosis.

METHODS

To assess the diagnostic utility of multiple, concurrent FC analyses, a 10-year retrospective review of cases with ≥2 concurrent specimens (from the same patient) submitted for FC was conducted. Light microscopic (LM) diagnoses were compared to FC findings, and the contribution of FC results to final diagnoses was examined.

RESULTS

Of 4058 specimens (predominantly lymph nodes, bone marrows, and oropharyngeal tissues) submitted for FC analyses, 129 (3.2%) represented cases with multiple (average: 2.19) concurrent FC analyses. All were accompanied by tissues and/or aspirates for LM examination. In 115 (89.1%) cases, multiple FC analyses were performed prior to morphologic examination. In 87.0% of those cases, ≥1 FC result(s) aligned with LM findings. In 15 (13.0%) cases where FC results differed from morphologic diagnoses, 86.7% (13/15) failed to detect an abnormal cell population by FC in the presence of a hematologic malignancy by LM. In one case (0.9%), FC detected a lymphoma, without morphologic evidence by LM.

CONCLUSIONS

Overall, multipart FC failed to demonstrate a significant contribution in initial diagnoses of hematologic malignancies compared with analysis of a single specimen.

A pipeline for automated analysis of flow cytometry data: preliminary results on lymphoma sub-type diagnosis

Flow cytometry (FCM) is widely used in health research and is a technique to measure cell properties such as phenotype, cytokine expression, etc., for up to millions of cells from a sample. FCM data analysis is a highly tedious, subjective and manually time-consuming (to the level of impracticality for some data) process that is based on intuition rather than standardized statistical inference. This study proposes a pipeline for automatic analysis of FCM data. The proposed pipeline identifies biomarkers that correlate with physiological/pathological conditions and classifies the samples to specific pathological/physiological entities. The pipeline utilizes a model-based clustering approach to identify cell populations that share similar biological functions. Support vector machine (SVM) and random forest (RF) classifiers were then used to classify the samples and identify biomarkers associated with disease status. The performance of the proposed data analysis pipeline has been evaluated on lymphoma patients. Preliminary results show more than 90% accuracy in differentiating between some sub-types of lymphoma. The proposed pipeline also finds biologically meaningful biomarkers that differ between lymphoma subtypes.

Variable CD52 expression in mature T cell and NK cell malignancies: implications for alemtuzumab therapy

The anti-CD52 antibody alemtuzumab has been explored as a novel targeted therapy in T cell malignancies. To assess the suitability of alemtuzumab therapy, we carried out a comprehensive study of CD52 expression using flow cytometry (FC) in 78 untreated patients diagnosed with mature T/natural killer (NK) cell neoplasms, including 34 adult T cell leukaemia/lymphomas (ATLL), two anaplastic large cell lymphomas (ALCL), three angioimmunoblastic T cell lymphomas (AITL), 16 cutaneous T cell lymphomas (CTCL), four extra-nodal T/NK cell lymphomas (ENT/NKCL), four hepatosplenic T cell lymphomas (HSTCL), 13 peripheral T cell lymphomas, not otherwise specified (PTCL-NOS) and two T-prolymphocytic leukaemia (T-PLL). The level of CD52 expression was quantified using QuantiBRITE standard beads. The level of CD52 expression varied widely within each diagnostic category. All AITL, HSTCL and T-PLL cases were CD52-positive and the frequency of CD52 expression was high in PTCL-NOS (92.3%), ATLL (94.1%) and CTCL (87.5%), implying a rational role for alemtuzumab in the treatment of these diseases; however, CD52 expression was low in ALCL (50%) and ENT/NKCL (25%). FC testing for cell surface expression of CD52 is indicated in patients with T/NK cell malignancies being considered for alemtuzumab therapy. Further studies are necessary to determine if the level of CD52 expression correlates with response to therapy.

Flow cytometric immunophenotyping (FCI) of lymphoma: correlation with histopathology and immunohistochemistry

BACKGROUND

To evaluate the role of flow cytometric immunophenotyping (FCI) in diagnosis and characterization of lymphoma tissue specimens from Egyptian patients.

METHODS

FCI using 2 and 3 color staining approaches, was performed on 50 fresh lymph nodes specimen from Cairo NCI patients with suspected lymphoma presenting with either localized or generalized lymphadenopathy.FCI results were correlated with histopathologic as well as immunophenotypic[by immunohistochemistry (IHC)] findings.

RESULTS

By FCI, cases were diagnosed as follows: 9(18%) reactive hyperplasia (RH), 32(64%) B-cell non-Hodgkin's lymphoma (B-NHL) [24 diffuse large (DLBCL), 2 follicular, 3 small lymphocytic, 2 mantle cell lymphoma and a case of T cell rich B cell lymphoma], 3 (6%) T cell NHL [2 peripheral T cell lymphoma and a case of anaplastic large cell lymphoma], 2(4%) Hodgkin's lymphoma (HL) while 4 (8%) were non-lymphomatous tumors (NLT). Light chain restriction (LCR) was detected in the 32 FCI diagnosed B-NHL. The overall concordance between FCI versus histopathology and IHC was 88%. The sensitivity and specificity of FCI in diagnosis of NHL was 94.9% and 100% respectively; in HL they were 40% and 100% respectively and in NLT, both sensitivity and specificity were 100% while for RH were 100% and 89.1% respectively.

CONCLUSION

FCI is a sensitive and specific method in diagnosis and classification of NHL as well as in detection of monoclonality. False negative results could be due to the presence of heterogeneous populations of lymphocytes in special types of lymphoma.

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.

Flow-cytometric immunophenotyping of normal and malignant lymphocytes

During the past two decades, flow-cytometric immunophenotyping of lymphocytes has evolved from a research technique into a routine laboratory diagnostic test. Extensive studies in healthy individuals resulted in detailed age-related reference values for different lymphocyte subpopulations in peripheral blood. This is an important tool for the diagnosis of hematological and immunological disorders. Similar, albeit less detailed, information is now available for other lymphoid organs, e.g., normal bone marrow, lymph nodes, tonsils, thymus and spleen. Flow-cytometric immunophenotyping forms the basis of modern classification of acute and chronic leukemias and is increasingly applied for initial diagnostic work-up of non-Hodgkin's lymphomas. Finally, with multiparameter flow cytometry, it is now possible to identify routinely and reliably low numbers of leukemia and lymphoma cells (minimal residual disease).

Clin Chem Lab Med 2006;44:775–96.

Detection of CD5 in B-cell chronic lymphoproliferative diseases by flow cytometry: a strong expression in B-cell chronic lymphocytic leukemia

PURPOSE: CD5 is a T cell marker, aberrantly express in B cell chronic lymphocytic leukemia (B-CLL) and mantle cell lymphoma (MCL). Other chronic B cell malignancies including hairy cell leukemia (HCL) and B cell prolymphocytic leukemia (B-PLL) are CD5 negative or express this antigen in a weak way. In this study, CD5 expression was investigated in leukemic cells from 42 patients with chronic B cell lymphoproliferative disease. METHODS: We studied the CD5 expression in leukemic cells from 42 patients with chronic B-cell malignancies by flow cytometry. Demographic features such as age, sex and clinical date were also analyzed. RESULTS: There were 22 males and 20 females. The immunophenotyping showed that 35 cases were B-CLL, 3 B-PLL and HCL and one patient was MCL. CD5 expression was present in all B-CLL and MCL. Low expression of CD5 was observed in one patient with B-PLL and negative in all cases of HCL. CONCLUSION: Our date demonstrated that CD5 expression can help distinguish among B-CLL from HCL and B-PLL, but is similar expressed in MCL.

High incidence of occult leptomeningeal disease detected by flow cytometry in newly diagnosed aggressive B-cell lymphomas at risk for central nervous system involvement: the role of flow cytometry versus cytology

We assessed the cerebrospinal fluid (CSF) by flow cytometry and cytology in 51 newly diagnosed and 9 treated aggressive B-cell lymphomas at risk for central nervous system (CNS) involvement to examine the utility of flow cytometry, incidence of CSF disease, and clinical surrogates of CNS spread. Multicolor flow cytometry using multiple antibody panels for light chains and B- and T-cell antigens identified neoplastic clones that constituted as little as 0.2% of total CSF lymphocytes. Among 51 newly diagnosed patients, 11 (22%) had occult CSF involvement. All 11 were detected by flow cytometry but only 1 by cytology (P = .002). Among 9 treated patients, CSF involvement was detected by flow cytometry alone in 2 and also by cytology in 1 case. CSF chemistry and cell counts were similar in patients with and without CSF lymphoma. Only the number of extranodal sites was associated with occult CSF lymphoma in newly diagnosed patients by univariate (P = .006) or logistic regression analysis (P = .012). We hypothesize that the biologic phenotype associated with colonization of extranodal sites leads to CNS spread, possibly related to the microenvironment. Patients at risk for CNS spread should undergo staging CSF evaluation by flow cytometry.

Clinical utility of bone marrow flow cytometry in B-cell non-Hodgkin lymphomas (B-NHL)

AIM

To determine the efficacy of flow cytometry (FC) in the assessment of bone marrow (BM) in B-cell non-Hodgkin lymphoma (B-NHL). FC is a common practice, but is far from being validated.

METHODS AND RESULTS

Morphological analysis and FC immunophenotyping were performed on 421 samples. T-cell lymphomas, Hodgkin's disease, chronic lymphocytic leukaemia and hairy cell leukaemia were not included in the study. Clonality was assessed by the standard kappa/lambda/CD19 test. Aberrant immunophenotypes present in the B-cell subpopulation were also investigated. A double-step procedure was employed in all cases to increase the sensitivity of the FC procedure. Of 380 evaluable samples, 188 corresponded to follicular lymphoma (FL), 58 to diffuse large B-cell lymphoma (DLBCL), 57 to mantle cell lymphoma (MCL), seven to Burkitt's lymphoma and the remaining 70 samples to other low-grade lymphomas. Morphological marrow infiltration was found in 148 cases, and flow immunophenotyping identified 138 cases with BM involvement. A concordance between the two methods was detected in 298 cases (79%). There was a discordance in 82 cases (21%): morphology positive/FC negative in 46 cases and morphology negative/FC positive in 36 (61% of all cases with discordance were from FL). There was no difference in outcome when patients with discordances were compared with patients without discordances.

CONCLUSIONS

Most samples showed concordance between morphological and FC results. FC identified BM involvement in the absence of morphological infiltration. Morphology/FC discordance seems to have no influence on the outcome of FL patients.

Flow cytometry in lymphoma diagnosis and prognosis: useful?

Flow cytometry has become an important tool in the diagnosis of mature lymphoid neoplasms and the determination of prognosis in selected cases. The advantages of flow cytometry are based largely on its ability to analyse, rapidly and simultaneously, multiple cell properties in a quantitative manner. Flow cytometric immunophenotyping is useful in diagnosing lymphoma under the WHO classification system, where lymphoid neoplasms are separated into distinct clinical entities based upon morphology, immunophenotype, genetic abnormalities and clinical features. Flow cytometry can quantify the expression of proteins associated with a good or poor prognosis, detect multidrug resistance, and measure cell proliferation, making it useful in measuring prognostic indicators in lymphoid neoplasia. The unique attributes of flow cytometry therefore make it a valuable technique in the diagnosis and classification of lymphomas as well as the assessment of prognostic markers in lymphoma patients.

Flow cytometry in the bone marrow staging of mature B-cell neoplasms

BACKGROUND

Even though flow cytometric (FC) analysis of bone marrow aspirates is often performed in hematolymphoid disorders at diagnosis and during disease monitoring, its role has not been defined during the staging of B-non-Hodgkin's lymphoma (B-NHL) and B-cell lymphoproliferative diseases. The goal of this study was to provide an objective evaluation of how FC might help in the detection of bone marrow involvement by the different types of B-cell malignant neoplasms.

METHODS

Fifty-four staging and 156 restaging bone marrow biopsies and bone marrow aspirates, obtained from 185 consecutive patients, were analyzed retrospectively. The results of the morphologic examination and FC were reviewed independently, and their ability to detect bone marrow involvement was compared.

RESULTS

FC and morphology agreed in 176 cases (83.8%), i.e., both showed 77 positive cases and 99 negative ones. Discrepant results were obtained in 30 cases (14.2%) in which morphologic examination showed 25 (11.9%) positive cases, whereas FC showed no evidence of disease. FC detected involvement in five cases (2.4%) in the presence of a histologically negative bone marrow biopsy. All morphologically undetermined bone marrow cases (four) were negative by FC.

CONCLUSIONS

Neither morphologic examination nor FC alone is adequate for the detection of all cases of B-lymphoid neoplasm bone marrow involvement. FC failed to detect bone marrow involvement in those B-NHL cases having focal paratrabecular infiltration, but proved to be more sensitive than histology in detecting small clonal B-cells in B-NHL, which demonstrated fewer than 5% neoplastic infiltrates. The clinical relevance of minimal disease detected by FC alone needs further evaluation because staging of lymphomas currently is based only on morphologic data.

An approach to diagnosis of T-cell lymphoproliferative disorders by flow cytometry

T-cell lymphoproliferative disorders are among the most challenging diagnoses in hematopathology. Unlike the more common B-cell disorders, in which clonality is often readily discernible by surface immunoglobulin light chain restriction, there is no specific immunophenotypic signature that is diagnostic of a clonal T-cell population. Immunophenotypic criteria that are helpful in the diagnosis of T-cell neoplasms include T-cell subset antigen restriction, anomalous T-cell subset antigen expression, deletion or diminution of one of the pan T-cell antigens, a precursor T-cell phenotype, and expression of additional markers (e.g., CD30, CD20, major myeloid antigens, and TCRgammadelta). Analysis of the inherent forward and orthogonal light scatter properties of the cell can also provide important diagnostic clues. None of these features is 100% specific, however, for aberrant expression of pan-T antigens may be seen in viral infections, B-cell malignancies, or in reactive changes following administration of certain medications. An increased CD4:CD8 ratio is often observed in Hodgkin's lymphoma. Based on the analysis of 87 neoplastic and 80 control cases, we conclude that flow cytometric features that are most suspicious for malignancy include the loss or markedly dim expression of CD45; complete loss of one or more pan-T antigens; diminished expression of more than two pan-T antigens in conjunction with altered light scatter properties; and CD4/CD8 dual-positive or dual-negative expression (except thymic lesions).

Clonal heterogeneity assessed by flow cytometry in B-cell lymphomas arising from germinal centers

Patients with mature follicular B-cell lymphomas develop aggressive non-Hodgkin lymphomas (NHLs) during disease progression. It is controversial whether most diffuse large B-cell lymphomas (DLBCLs) and Burkitt lymphomas (BLs) emerge as de novo lymphomas or from an original follicular lymphoma. To distinguish clonally related populations in aggressive NHL, we studied the immunophenotypic features of 18 consecutive samples from 16 patients. Three flow cytometric patterns were distinguished: (1) a homogeneous neoplastic population of large B cells with phenotypic features of follicular center cells; (2) 2 atypical populations of B cells, small monoclonal B cells, and large B cells with loss of some surface antigens; and (3) 2 clonal populations of small and large B cells sharing the same light-chain isotype. The 3 flow cytometric patterns were observed, respectively, in de novo DLBCL and BL, transformation into BL, and transformation into DLBCL. Flow cytometric data can provide valuable information about the natural history of NHL.

Use of novel t(11;14) and t(14;18) dual-fusion fluorescence in situ hybridization probes in the differential diagnosis of lymphomas of small lymphocytes

Increasingly, molecular biologic techniques have become important in the diagnosis of non-Hodgkin lymphomas. In the differential diagnosis of lymphoma(s) of small lymphocytes (LSL), reliable detection of t(11;14) or t(14;18) would confirm the diagnosis of mantle cell lymphoma (MCL) or follicle center lymphoma (FCL), respectively. A total of 87 LSL cases (27 MCL, 39 FCL, 17 small lymphocytic lymphoma [SLL], 3 marginal zone lymphomas, and 1 paraimmunoblastic variant of SLL) were diagnosed by a combination of light microscopy, immunohistochemistry, and flow cytometric immunophenotyping. Interphase fluorescence in situ hybridization (FISH) for t(11;14) and t( 14;18) using dual-fusion probes (Vysis, Downers Grove, IL) was performed on touch (n = 69) or gravity (n = 18) preparations from these cases. Of 27 MCL cases tested, 25 (93%) had demonstrable t(11;14), none had t(14;18), and 2 were negative for t(11;14) and t(14;18). Twenty-five of 39 (64%) FCL cases had t(14;18), none had t(11;14), and the remaining FCL cases (14 cases [35%]) had neither t(11;14) nor t(14;18). All 17 (100%) SLL cases had neither t(11;14) nor t(14;18). All 3 (100%) marginal zone lymphoma cases had neither t(11;14) nor t(14;18). The case of paraimmunoblastic variant of SLL had t(11;14) and was negative for t(14;18). No discrepant [i.e., positive for both t(11;14) and t(14;18)] or false-positive cases were noted. Interphase FISH using these commercially available probes is a useful adjunct to light microscopy, immunohistochemistry, and flow cytometric immunophenotyping in the diagnosis of LSL. FISH can be performed successfully on archival single-cell preparations (touch preparations or gravity preparations) when fresh tissue is unavailable. No discordant or false-positive cases were identified.

Immunophenotypic analysis of simultaneous specimens from different sites from the same patient with malignant lymphoma

Immunophenotypic analysis of simultaneous specimens from different sites from the same patient with malignant lymphoma The assumption that immunophenotypic characteristics of different specimens obtained simultaneously from the same patient remain unchanged has rarely been evaluated. Using flow cytometry, we reviewed our experience of 29 patients with non Hodgkin's lymphoma (NHL). From these patients, 60 simultaneous specimens taken from the peripheral blood, bone marrow, effusions, fine needle aspirates from lymph nodes or cerebrospinal fluid were studied. In 26 out of 29 patients, the immunophenotype in the different specimens was identical. In one patient with unclassifiable low-grade B-NHL, immunophenotyping showed additionally a CD38 expression in the effusion which was not seen in the bone marrow. In one patient with mantle cell lymphoma, expression of CD10 in the lymph node was noted which was lacking in the peripheral blood. In the remaining patient with unclassifiable low-grade B-NHL, CD23 expression was noted in the lymph node but not in the peripheral blood. This retrospective study suggests that discordant antigen expression in samples from different body sites within the same patient is a rare event.

Flow cytometry using the monoclonal antibody CD10-Pe/Cy5 is a useful tool to identify follicular lymphoma cells

Follicular lymphoma (FL) is a specific entity defined by characteristic histology, phenotype and molecular rearrangements. Classically, reactivity for CD19, CD10, and strong positivity for the surface light chain immunoglobulin (SIg) are considered to be phenotypic signs typically expressed in FL. In practice, this pattern is difficult to identify since most neoplastic cells analysed by flow cytometry (FC) show weak intensity for CD19-Pe/Cy5 and for SIg and negativity for CD10-FITC. We used triple antigen combinations including two monoclonal antibodies (MoAbs) against CD10 (CD10-FITC and CD10-Pe/Cy5) and a long-distance polymerase chain reaction (PCR) approach to establish the phenotypic pattern of neoplastic cells carrying t(14;18)(q32;q21). Neoplastic cells showed the following immunophenotype: stronger reactivity against CD20 than against CD19, positivity for CD22 and SIg and negativity for CD5, CD11c and CD10-FITC. Characteristically, CD10-Pe/Cy5 was expressed in all the samples with positive bcl-2/JH rearrangements. In FL, there was a high correlation between histologic diagnosis and reactivity against CD10-Pe/Cy5 (96% cases). In diffuse large cell lymphomas (DLCL), CD10-Pe/Cy5 identified positive cases with t(14;18)(q32;q21) chromosomal translocation, whereas Burkitt lymphomas showed all cases reactivity against CD10-Pe/Cy5. In conclusion, CD10-Pe/Cy5 is a useful antibody for identifying neoplastic cells carrying t(14;18)(q32;q21) in FL and DLCL. In combination with other MoAbs, anti-CD10 (HI10a, Cy-Chrome) can be used to identify a characteristic phenotypic profile of FL against other lymphoproliferative disorders.

Diagnosis of peripheral T-cell lymphoma by fine-needle aspiration biopsy: a cytomorphologic and immunophenotypic approach

The diagnosis of T-cell lymphomas by fine-needle aspiration biopsies (FNAB) is extremely difficult. This is mainly due to the rarity of the disease, the morphologic similarity to reactive lymphadenopathy, and the difficulty in identifying abnormal T-cell antigen expression. We studied FNAB of histologically proven T-cell lymphomas in an attempt to identify the salient cytomorphologic features as well as the surface marker attributes of the disease. Twenty cases were reviewed. The smears were evaluated for overall cytologic pattern and percentage of abnormal cells. A critical review of flow cytometric (FCM) antigen expression of the lymphomas was also performed. There were 6 female and 14 male patients, with an age range of 9-84 yr (median, 36 yr). Fourteen cases (70%) showed polymorphous smears, and 6 cases (30%) showed monomorphous smears. Abnormal cells ranged from 10-100% (median, 60%). Abnormal T-cell antigen expression by FCM analysis was seen in 17 cases (85%). The most common aberrant T-cell antigen pattern was loss of 3 or more pan-T-cell antigens (n = 10). The most common individual T-cell antigen loss was that of CD7 (n = 10), followed by loss of CD5 (n = 5). There was also loss of CD4 and CD8 (n = 5), loss of CD5 and CD7 (n = 5), complete loss of CD3 (n = 4), coexpression of CD4 and CD8 (n = 1), and partial loss of CD3 (n = 1). CD56 was expressed in 2 cases. CD1a was tested in one case and was positive. CD4/CD8 ratio was elevated (>2.5) in 9 cases (53%), with a range of 3/1-57/1 (median, 12/1). TCR gene rearrangement using PCR was positive in 7 of 9 tested cases. Our findings suggest that the diagnosis of peripheral T-cell lymphomas can be achieved by FNAB in the majority of cases through close analysis of the morphology. This can be supported by a critical analysis of the phenotype using two or three-color flow cytometry with an attempt at identification of one or more abnormal T-cell antigen expression and/or loss. This can be supplemented by CD4/CD8 ratios and T-cell receptor gene rearrangement analysis.

Contribution of flow cytometric immunophenotyping to the evaluation of tissues with suspected lymphoma?

BACKGROUND

A critical analysis of the contribution of flow cytometric immunophenotyping (FCI) to the evaluation of lymph nodes and extranodal tissues with suspected lymphoma by a large, retrospective approach has not been reported previously and represents the purpose of this study.

METHODS

A total of 278 lymph nodes and 95 extranodal tissue specimens submitted over a 2-year period with complete histologic, FCI, and immunohistochemical (IH) data formed the basis of the study.

RESULTS

The FCI data contributed significantly to or was consistent with the final tissue diagnosis in the majority (94%) of the tissue samples. There is no well-described utility of flow cytometry markers for Hodgkin's lymphoma (HL) due to the usual scarcity of tumor cells in the final cell suspensions obtained from these tumors. However, the FCI data excluded non-Hodgkin's lymphoma (NHL) and suggested the possible usefulness of CD15 and CD30 by FCI in HL. In addition, immunophenotypic data by FCI in combination with touch imprint cytomorphology was useful in excluding a diagnosis of NHL in cases of nonhematopoietic malignancies and was particularly useful in defining the following hematopoietic tumors and malignancies: thymoma, T-cell lymphoblastic lymphoma, leukemia cutis, and plasma cell dyscrasia. Thus, IH was not essential for the diagnosis in these latter cases and was performed in only two cases (one thymoma and one plasma cell dyscrasia). Of interest, FCI supported the diagnosis in 3 cases of Ewing's sarcoma/primitive neuroectodermal tumor by detection of CD56 on the surface of the malignant cell. Only 11% of NHL were "negative" by FCI (i.e., an aberrant T-cell or monoclonal B-cell population was not identified). Reasons for these discrepancies included partial tissue involvement by the NHL with sampling differences, T-cell rich or lymphohistiocytic-rich variants with a small population of monoclonal B cells, marked tumoral sclerosis, poor tumor preservation, and T-cell NHL without an aberrant immunophenotype. Only 60% of CD30+ anaplastic large cell lymphomas (ALCL) were CD30+ by FCI.

CONCLUSIONS

FCI data should always be correlated with light microscopy if no FCI abnormalities are detected; IH may need to be performed in selected cases. It is less necessary to perform microscopic examination of tissues when the FCI data are positive and indisputable. However, in selected cases in which FCI data is diagnostic, microscopic observations may provide additional information due to sampling.

Flow Cytometry: Principles and Clinical Applications in Hematology

The use of flow cytometry in the clinical laboratory has grown substantially in the past decade. This is attributable in part to the development of smaller, user-friendly, less-expensive instruments and a continuous increase in the number of clinical applications. Flow cytometry measures multiple characteristics of individual particles flowing in single file in a stream of fluid. Light scattering at different angles can distinguish differences in size and internal complexity, whereas light emitted from fluorescently labeled antibodies can identify a wide array of cell surface and cytoplasmic antigens. This approach makes flow cytometry a powerful tool for detailed analysis of complex populations in a short period of time. This report reviews the general principles in flow cytometry and selected applications of flow cytometry in the clinical hematology laboratory.

Expression of T-cell-associated antigens in B-cell non-Hodgkin's lymphoma

We performed the immunophenotyping of 101 patients with B-cell non-Hodgkin's lymphoma (B-NHL) using two-colour flow cytometry (FCM) and found that lymphoma cells coexpressed at least one kind of T-cell-associated antigen (T-Ag; CD2, CD5, CD7) in 25 patients (24. 8%). Among these three T-Ags, CD5 was the most frequently expressed, in 21 patients (20.8%), followed by CD7, expressed in five patients (5.0%), and CD2, which was expressed in two patients (2.0%). Two kinds of T-Ag were simultaneusly expressed in three patients (CD2/CD5, CD2/CD7, and CD5/CD7, each expressed in one patient). Concerning the expression pattern of T-Ag, there were no significant differences between lymph nodes and extranodal organs in the three patients with T-Ag-positive B-NHL (T-Ag(+) B-NHL) who were analysed. When comparing the clinical features between T-Ag(+) B-NHL and T-Ag-negative B-NHL (T-Ag(-) B-NHL), extranodal involvement and higher International Prognostic Index (H and H.I.) were significantly frequent in the former subgroup (P = 0.0119 and P = 0. 0302 respectively).

Immunophenotypic Analysis of Peripheral Blood and Bone Marrow in the Staging of B-Cell Malignant Lymphoma

This study evaluated the contributing roles of flow cytometric immunophenotyping of blood and bone marrow and immunohistochemical paraffin section staining of bone marrow biopsies in the staging of B-cell malignant lymphoma. Flow immunophenotyping was performed on a marrow specimen in 175 cases; a corresponding blood specimen was also immunophenotyped in 135 of these cases. Morphologic marrow involvement by lymphoma was found in 59 cases; flow immunophenotyping identified 54 cases with a monoclonal B-cell process: morphology-positive/flow-positive (n = 49), morphology-positive/flow-negative (n = 10), morphology-negative/flow-positive (n = 5), and morphology-negative/flow-negative (n = 111). The 10 morphology-positive/flow-negative cases included 5 follicular and 5 large-cell lymphomas with minimal marrow involvement. All 5 morphology-negative/flow-positive cases were from patients with large-cell lymphomas and bulky clinical disease. Because the blood contained the same B-cell clone in 2 of 2 morphology-negative/flow-positive cases studied, blood contamination of marrow may account for these findings. Blood flow cytometric immunophenotyping studies were positive in 32 cases; 30 had marrow involvement by morphology and were from patients with follicular, mantle cell, lymphoplasmacytic, small lymphocytic, or marginal zone lymphomas. From our results, we conclude that (1) bone marrow flow cytometric immunophenotyping is not a cost-effective replacement for good morphologic evaluation in lymphoma staging and that (2) a positive peripheral blood flow cytometric immunophenotyping study when performed in low-grade lymphomas correlates with marrow involvement.

Immunophenotypic Analysis of Peripheral Blood and Bone Marrow in the Staging of B-Cell Malignant Lymphoma

This study evaluated the contributing roles of flow cytometric immunophenotyping of blood and bone marrow and immunohistochemical paraffin section staining of bone marrow biopsies in the staging of B-cell malignant lymphoma. Flow immunophenotyping was performed on a marrow specimen in 175 cases; a corresponding blood specimen was also immunophenotyped in 135 of these cases. Morphologic marrow involvement by lymphoma was found in 59 cases; flow immunophenotyping identified 54 cases with a monoclonal B-cell process: morphology-positive/flow-positive (n = 49), morphology-positive/flow-negative (n = 10), morphology-negative/flow-positive (n = 5), and morphology-negative/flow-negative (n = 111). The 10 morphology-positive/flow-negative cases included 5 follicular and 5 large-cell lymphomas with minimal marrow involvement. All 5 morphology-negative/flow-positive cases were from patients with large-cell lymphomas and bulky clinical disease. Because the blood contained the same B-cell clone in 2 of 2 morphology-negative/flow-positive cases studied, blood contamination of marrow may account for these findings. Blood flow cytometric immunophenotyping studies were positive in 32 cases; 30 had marrow involvement by morphology and were from patients with follicular, mantle cell, lymphoplasmacytic, small lymphocytic, or marginal zone lymphomas. From our results, we conclude that (1) bone marrow flow cytometric immunophenotyping is not a cost-effective replacement for good morphologic evaluation in lymphoma staging and that (2) a positive peripheral blood flow cytometric immunophenotyping study when performed in low-grade lymphomas correlates with marrow involvement.

The use of flow cytometry in the diagnosis and monitoring of malignant hematological disorders

Flow cytometry is a modality with ever increasing application in modern hematological practice. This is due to the rapidity of obtaining results, ease of use and increasing power to detect abnormal populations of cells. The major uses of flow cytometry in malignant hematology are in the diagnosis, classification and monitoring of diseases such as leukemia, lymphoma and myeloma. The technique is now used also to detect disease-specific populations of cells in paroxysmal nocturnal hemoglobinuria. This review describes the use of flow cytometry in many disease states.

Diagnosis of MALT lymphoma by conjunctival biopsy: a case report

BACKGROUND

Most extranodular lymphatic tissue is found in the intestinal mucosa. Together with similarly structured lymphatic tissue at other locations it has been named mucosa-associated lymphatic tissue (MALT). Malignant transformation of such tissue to lymphoma is well known. Although MALT lymphoma has been described in tissue physiologically void of MALT, lymphoma manifestation in the conjunctiva is rare.

METHODS

We report a case of a 47-year-old woman who was referred to our clinic for symptomatic treatment and evaluation of severe symptoms of dry eyes. She was thought to suffer from Sjögren's syndrome because of xerophthalmia and xerostomia, as well as massive bilateral swelling of the parotid gland. Ophthalmological examination revealed marked hyperplasia of the conjunctiva, of which a biopsy was taken.

RESULTS

Histological and immunohistochemical examination of the conjunctival biopsy, together with analysis of gene rearrangement by Southern blot, led to the diagnosis of low-grade B-cell lymphoma of the MALT.

CONCLUSION

The differential diagnosis of keratoconjunctivitis sicca presenting with conjunctival swelling of unknown origin should include lymphoma, especially since Sjögren's syndrome may be associated with malignant disorders of the lymphatic system. A biopsy of suspicious conjunctival changes can clarify a multisystem disease by providing a tissue diagnosis.