Large B-cell lymphomas: fine-needle aspiration plays an important role in initial diagnosis of cases which are falsely negative by flow cytometry

Factors determining whether diffuse large B-cell lymphoma samples are detected by flow cytometry

INTRODUCTION

Flow cytometry (FCM) is widely used in the diagnosis of mature B-cell neoplasms (MBN), and FCM data are usually consistent with morphological findings. However, diffuse large B-cell lymphoma (DLBCL), a common MBN, is sometimes not detected by FCM. This study aimed to explore factors that increase the likelihood of failure to detect DLBCL by FCM.

METHODS

Cases with a final diagnosis of DLBCL that were analysed by eight-colour FCM were retrospectively collated. Clinical, FCM, histopathological and genetic data were compared between cases detected and cases not detected by FCM.

RESULTS

DLBCL cases from 135 different patients were analysed, of which 22 (16%) were not detected by FCM. In samples not detected by flow cytometry, lymphocytes were a lower percentage of total events (p = 0.02), and T cells were a higher percentage of total lymphocytes (p = 0.01). Cases with high MYC protein expression on immunohistochemistry were less likely to be missed by FCM (p = 0.011). Detection of DLBCL was not different between germinal centre B-cell (GCB) and non-GCB subtypes, not significantly affected by the presence of necrosis or fibrosis, and not significantly different between biopsy specimens compared to fine-needle aspirates, or between samples from nodal compared to extranodal tissue.

CONCLUSION

The study identifies several factors which affect the likelihood of DLBCL being missed by FCM. Even with eight-colour analysis, FCM fails to detect numerous cases of DLBCL.

Imprint cytology: Invaluable technique to evaluate fresh specimens received in the pathology department for Lymphoma workup

At the time of intraoperative consultation, cytologic preparations including smears and imprints can be used in combination with frozen sections to increase diagnostic yield; however, these simple and rapid techniques are not adopted by all pathologists and their use varies considerably between institutions. In patients under investigation for suspected lymphoma, optimal triaging of tissue received fresh in pathology for lymphoma workup is paramount to maximize the odds of obtaining an accurate and clinically meaningful diagnosis and to avoid the need for additional procedures and delays in management, particularly in the current context in which core biopsies have become common practice as a first attempt to attain this goal. Imprint cytology is invaluable in this regard, also as these patients may not have a lymphoma but rather one of its clinical mimics. Herein, imprint cytology is used to approach fresh specimens received intraoperatively for lymphoma workup. More specifically, how these specimens are triaged for ancillary studies, such as flow cytometry, florescence in situ hybridization, or molecular analyses based on an interpretation of the touch imprints, is described. Detailed imprint cytological findings of typical benign and malignant lymphoid and nonlymphoid lesions are discussed and illustrated.

Grading of follicular lymphoma in cytological samples

OBJECTIVE

The treatment of follicular lymphoma (FL) depends on its grade. The current World Health Organization (WHO) 2008 Classification of Tumours of Haematopoietic and Lymphoid Tissues recommends the grading of FL on histological samples according to the Mann and Berard method, taking into consideration the number of centroblasts. There is no generally accepted method for the grading of FL in fine needle aspiration biopsy (FNAB) samples. The aim of the present study was to devise a grading system for FL in cytological samples.

METHODS

Flow cytometry (FC) was performed on 60 FNAB samples of patients with primary FL. We assumed that FL cells larger than reactive T lymphocytes on FC histograms corresponded to centroblasts. The percentage of large cells was calculated and compared with histological grade, proliferative activity and number of centroblasts per high-power field (HPF) on histological slides, and with survival.

RESULTS

The histological analysis of lymph nodes revealed 20 patients with high-grade and 40 patients with low-grade FL. The percentage of large cells in FNAB samples correlated significantly with histological grade (P = 0.02), MIB1 status (P < 0.001) and the number of centroblasts per HPF (P < 0.001). An age over 60 years and a percentage of large cells over 50% in FNAB samples were found to have a statistically significant impact on survival by univariate analysis (P = 0.001 and P = 0.006, respectively).

CONCLUSIONS

The percentage of large lymphoma cells in FNAB samples of FL determined by FC can be used as a reliable method for FL grading, as it is comparable with the histological grading system.

Flow cytometric immunophenotyping and cell block immunocytochemistry in the diagnosis of primary Non-Hodgkin's Lymphoma by fine-needle aspiration: Experience from a tertiary care center

Background:

Accurate diagnosis of Non-Hodgkin's Lymphoma (NHL) on fine-needle aspiration (FNA) specimen is challenging and requires ancillary testing.

Aim:

The feasibility of flow cytometric immunophenotyping (FCI) along with cell block immunocytochemistry (CB-ICC) as adjunct techniques in the diagnosis of NHL as per the current World Health Organization (WHO) classification was evaluated.

Materials and Methods:

All cases of suspected lymphoma underwent FNA, and the sample was triaged for light microscopic evaluation, FCI, and CB-ICC, and each case was classified as per the current WHO classification.

Results:

A total of 65 cases was analyzed which included 40 B-cell, 21 T-cell, and 4 unclassifiable lymphomas. Of 61 cases, FCI alone was contributory in 74% (45/61) cases whereas CB-ICC alone was contributory in 65.5% (40/61) cases in typing the lymphoma. In 11.4% (7/61) cases, the lymphoma could not be classified by either technique. Thus, in a total of 88.5% (54/61) cases a combination of FCI and CB-ICC from FNA enabled a diagnosis of lymphoma with its subtyping.

Conclusion:

Flow cytometric immunophenotyping and ICC on CBs are feasible on FNA material and are very useful in a suspected case of NHL especially when a biopsy may not be possible or feasible.

Cytopathology in the diagnosis of lymphoma

FNA is a simple, safe, and an inexpensive sampling technique that plays an important role in the evaluation of lymphadenopathy. The key to enhancing the accuracy of FNA diagnosis of lymphoma is the multi parameter approach in which the cytomorphologic features are evaluated in correlation with the results of ancillary studies and clinical context. A full understanding of the current lymphoma classification, clinical features associated with each lymphoma subtype and the impact of the diagnosis on patient management is essential in FNA diagnosis of lymphoma. It is also important to recognize the limitations of FNA in the primary diagnosis of some subtypes of lymphoma, and tissue biopsy should be recommended for a definitive diagnosis and subclassification in such cases.

Leveraging image cytometry for the development of clinically feasible biomarkers: evaluation of activated caspase-3 in fine needle aspirate biopsies

Quantitation of activated caspases in xenograft models by laser scanning cytometry has demonstrated mechanism-specific biological activity of Anti-Trail Receptor immunoglobulin therapies in situ. These preclinical data confirmed that caspase activation is an early event that precedes tumor regression. To apply this platform for clinical monitoring of caspase activation using fine needle aspirate (FNA) biopsies, additional assay feasibility and validation experiments need be addressed. Furthermore, important instrument parameters should be considered including the maintenance and operation of the cytometer in a controlled state to ensure aspects like data traceability, reliability, and integrity. In the present chapter we describe a method to evaluate caspase activation in Colo205 cells and fine needle aspirate tumors by slide-based, laser scanning cytometry. This approach can be applied to cell cultures, preclinical and clinical fine needle aspirate material.

Correlation between flow cytometry and histologic findings: ten year experience in the investigation of lymphoproliferative diseases

Objective: To demonstrate the advantages of correlating flow cytometry immunophenotyping with the pathology/ immunohistochemistry of lymph nodes or nodules in the diagnosis of lymphoproliferative diseases. Methods: A retrospective study was carried out of 157 biopsy or fine-needle aspiration lymph nodes/ nodule specimens taken from 142 patients, from 1999 and 2009. The specimens were simultaneously studied with fow cytometry and pathology at Hospital Israelita Albert Einstein. The specimens were prepared in hematoxylin/eosin, Giemsa, or monoclonal antibody stained slides for detecting specific antibodies for the purposes of pathology/immunohistochemical analysis. The samples were hemolyzed and marked with different monoclonal antibody panels for different antigens in fow cytometry immunophenotyping. Results: The diagnostic results of pathology/immunohistochemical studies and flow cytometry immunophenotyping agreed in 115 patients (81%), corresponding to 127 specimens, as follows according to the pathologic diagnosis: 63 patients with non-Hodgkin's B-cell lymphoma; 26 patients with reactive lymphoid hyperplasia; 5 patients with non-Hodgkin's T-cell lymphoma; 4 patients with atypical lymphoid proliferation; 5 patients with a chronic granulomatous inflammatory process; 5 patients with a non-hematologic diagnosis; 2 patients with granulocytic sarcoma; 2 patients with thymoma; 1 patient with byphenotypic leukemia; 1 patient with kappa plasmocytoma; 1 patient with Hodgkin's lymphoma. Subtypes of lymphomas could be classified by associating the two techniques: 19 patients with follicular lymphoma; 15 patients with diffuse large B-cell lymphoma; 7 patients with small lymphocytic B-cell lymphoma/chronic lymphocytic leukemia; 3 patients with mantle cell lymphoma; 1 patient with Burkitt's lymphoma; 1 patient with MALT type lymphoma; 1 patient with post-transplant lymphoproliferative disease; 2 patients with high grade non-Hodgkin's B-cell lymphoma; 1 patient with low grade non-Hodgkin's B-cell lymphoma not otherwise specified; 1 patient with Hodgkin's lymphoma; and 12 patients with B-cell non-Hodgkin's lymphoma not otherwise specified. Conclusion: Flow cytometry adds to the results of morphologic and immunohistochemical studies, facilitating a rapid and accurate diagnosis of lymphoproliferative diseases.

Independent diagnostic accuracy of flow cytometry obtained from fine-needle aspirates: a 10-year experience with 451 cases

Although the topic is somewhat contentious, fine-needle aspiration (FNA) is frequently used in conjunction with flow cytometry (FC) to evaluate lymphoid proliferations. Despite the fact that the FNA and FC are often analyzed independently, no previous large-scale study has independently analyzed FC of FNA specimens. FC reports of 511 FNAs were retrospectively reviewed and FC diagnoses categorized as monoclonal, atypical, normal/reactive, or insufficient cellularity (3.9%). Abnormal immunophenotype was considered a positive test result. "Gold standard" diagnoses were established by histologic examination, treatment based on FNA, or clinical features. In 92.2% (451/489), there was adequate follow-up. The diagnostic accuracy of FC was 88.4%, sensitivity was 85.8%, and specificity was 92.9%. In addition, FC accuracy for classes of non-Hodgkin lymphoma was assessed. We conclude that FC is an independently accurate ancillary test in the evaluation of FNA. However, the presence of false-negative and false-positive cases supports the common practice of correlating FC with cytomorphologic findings even if performed independently.

Fine-needle aspiration cytology and flow cytometric immunophenotyping in diagnosis and classification of non-Hodgkin lymphoma in comparison to histopathology

This prospective study aimed to compare the value of fine needle aspiration (FNA) cytology (FNAC) and flow cytometric immunophenotyping (FCI) with histopatopathology (HP) in the diagnosis and classification of non-Hodgkin lymphoma (NHL). Twenty-nine excised lymph nodes suspected of NHL were evaluated using FNAC, FCI, and HP. Specimens were divided into two equal parts; one for HP and the other for FNAC and FCI. Results were compared in terms of diagnosis (malignant, benign or reactive, and metastatic) and NHL class. With combined FNAC/FCI, 11 (37.9%) cases were diagnosed as NHL, 11 cases (37.9%) as reactive lymph node, six cases (20.6%) as Hodgkin's lymphoma, and one case (3.4%) as metastasis. HP revealed nine cases (31%) of NHL, five cases (17.2%) of reactive lymph nodes and all the diagnosed metastatic and Hodgkin's lymphoma. Considering histology as a gold standard method in diagnosis, the sensitivity, specificity, PPV and NPV of FNAC/FCI in differentiate malignant and benign lesion were 73.9%, 83.3%, 94.4%, and 45.5%, respectively and in differentiate NHL from others were 75%, 93.8%, 90%, and 83.3%, respectively. Cytology and HP in addition to FCI and HP are significantly different from determination of NHL lesions point of view (P = 0.001 and P < 0.0001, respectively). However, FCI can be considered as an adjunctive method for Cytology especially because Cytology is not competent enough to differentiate between benign lesions and Lymphoma. Additionally, FCI is shown to be an accurate method in classifying NHL.

Microfluidic sorting and multimodal typing of cancer cells in self-assembled magnetic arrays

We propose a unique method for cell sorting, "Ephesia," using columns of biofunctionalized superparamagnetic beads self-assembled in a microfluidic channel onto an array of magnetic traps prepared by microcontact printing. It combines the advantages of microfluidic cell sorting, notably the application of a well controlled, flow-activated interaction between cells and beads, and those of immunomagnetic sorting, notably the use of batch-prepared, well characterized antibody-bearing beads. On cell lines mixtures, we demonstrated a capture yield better than 94%, and the possibility to cultivate in situ the captured cells. A second series of experiments involved clinical samples--blood, pleural effusion, and fine needle aspirates--issued from healthy donors and patients with B-cell hematological malignant tumors (leukemia and lymphoma). The immunophenotype and morphology of B-lymphocytes were analyzed directly in the microfluidic chamber, and compared with conventional flow cytometry and visual cytology data, in a blind test. Immunophenotyping results using Ephesia were fully consistent with those obtained by flow cytometry. We obtained in situ high resolution confocal three-dimensional images of the cell nuclei, showing intranuclear details consistent with conventional cytological staining. Ephesia thus provides a powerful approach to cell capture and typing allowing fully automated high resolution and quantitative immunophenotyping and morphological analysis. It requires at least 10 times smaller sample volume and cell numbers than cytometry, potentially increasing the range of indications and the success rate of microbiopsy-based diagnosis, and reducing analysis time and cost.

Role of endoscopic ultrasound-guided fine-needle aspiration with flow cytometry to diagnose lymphoma: a single center experience

BACKGROUND AND AIM

The use of endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) +/- flow cytometry (FC) for the diagnosis of suspected lymphoma remains controversial. We report our experience and diagnostic yield for EUS +/- FC for suspected lymphoma.

METHODS

Databases were queried for those who underwent EUS-FNA +/- FC for suspected lymphoma. Hospital charts were reviewed to confirm the final cytological diagnosis, follow up and FC results if obtained. The final diagnosis was confirmed by the results of EUS-FNA +/- FC, other biopsy and/or follow up.

RESULTS

In total, 54 patients underwent EUS-FNA of 72 lesions. The final diagnosis of lymphoma was made in 38 of the 54 (70%) patients, and 33 of the 54 (61%) patients relied on EUS-FNA. Cytopathology in 41 patients using EUS-FNA + FC showed lymphoma in 24 patients, atypical lymphoid cells in six and reactive lymph node in 11. In 9 of the 24 with lymphoma by EUS + FC, the diagnosis was confirmed by another diagnostic modality, like surgery, bone marrow biopsy and computed tomography-guided biopsy. Of the six with atypical lymphoid cells, additional diagnostic methods confirmed lymphoma in three. The remaining 13 of the 54 patients underwent EUS-FNA without FC due to insufficient sample (n = 5) or operator choice (n = 8). Cytopathology in these 13 patients without FC showed lymphoma (9), atypical lymphoid cells (3) and reactive node (1). The sensitivity, specificity, positive predictive value, negative predictive value and accuracy of EUS-FNA for lymphoma in all 54 patients ranged from 80% to 87%, 92% to 93%, 97%, 60% to 75% and 83% to 89%, respectively.

CONCLUSIONS

EUS-FNA is sensitive and specific for the diagnosis of suspected lymphoma. Confirmatory or further testing should be performed when EUS-FNA with or without FC is indeterminate and or non-diagnostic.

Role of fine-needle aspirate immunophenotyping by flow cytometry in rapid diagnosis of lymphoproliferative disorders

Immunophenotyping is an essential component in the diagnostic work-up of lymphoproliferative disorders (LPD). As compared to immunohistochemistry, flow cytometric immunophenotyping (FCMI) is rapid, quantitative and a more objective technique. This study was designed to evaluate the utility of FCMI on fine needle aspirates (FNA) in rapid diagnosis of LPD in routine clinical practice. FNA from 31 consecutive cases clinically suggestive of LPD were subjected to FCMI. Representative material for FCMI was obtained in 28 (90%) cases and a definite diagnosis established in 27 cases. Histopathogical correlation was available in 22 cases and concordance with FCMI results was observed in 19 (86.4%) cases. FCMI analysis was inconclusive in 4 cases. The results of FCMI were available the same day and were crucial for therapeutic purpose in 3 patients with superior vena cava syndrome. FCMI combined with cytological examination of aspirate smears permits rapid diagnosis with high level of accuracy resulting in efficient treatment planning for critically ill patients and those from far-off rural areas.

Grading follicular lymphomas in fine-needle aspiration biopsies

BACKGROUND

The World Health Organization (WHO) recommends a 3-tier grading system (Grades 1-3) for follicular lymphomas (FLs) based on the absolute number of centroblasts per high-power microscopic field (HPF) in 10 neoplastic follicles. Grades 1 and 2 FL are still managed as indolent FLs, whereas Grade 3 FL is thought to behave more aggressively. In this study, the feasibility of grading FL using ThinPrep (TP) slides and flow cytometry (FC) was evaluated.

METHODS

Fifty-three cases of lymph node fine-needle aspiration (FNA) from patients with histologically confirmed FL (20 Grade 1, 17 Grade 2, and 16 Grade 3) were included. The number of centroblasts present in 300 lymphoid cells and in 10 HPF in TP Papanicolaou-stained slides was evaluated. The percentage of CD10-positive small cells was calculated with FC results. Statistical analysis was performed with the Jonckheer-Terpstra nonparametric trend test and the Wilcoxon rank sum test.

RESULTS

The statistical analysis demonstrated a significant upward trend in the number of centroblasts as the grades increased. Also, all 3 methods had statistically significant results to distinguish different grades of FL, except when FC was used to distinguish Grade 2 from Grade 3 FL.

CONCLUSIONS

Counting centroblasts, either in 300 lymphoid cells or per 10 HPF in TP slides, represented a statistically significant method to separate different grades of FL in FNA samples. Analysis of cell size by FC was not as reliable to distinguish different grades of FL, especially Grade 2 from 3.

Fine-needle aspiration cytology in the diagnosis of superficial lymphadenopathy: a 5-year Brazilian experience

To determine the accuracy of fine-needle aspiration (FNA) in the diagnostic assessment of lymphadenopathies, a retrospective study was conducted on 627 cases of FNA of the lymph nodes performed at Department of Pathology, UNIFESP (Federal University of São Paulo), between 1997 and 2001. Cytology results were compared to the results of biopsies if available. The cytological diagnosis was unsatisfactory in 14.7% of cases, positive in 46%, and negative in 39.3%. Among the positive cases, 79.4% were classified as metastases, 14.2% as lymphoma, and 6.4% as indeterminate. Anatomopathological exams for the determination of cytohistological correlation were available in 218 of the 627 cases. There were three (1.88%) false-negative and two (1.25%) false-positive cases. Accuracy tests revealed 97.41% sensitivity, 95.45% specificity, and 96.88% efficacy, with cytohistological agreement being almost perfect (kappa = 0.92). The high accuracy of this study based only on cytomorphological criteria associated to the variety of malignant neoplasias diagnosed by the procedure demonstrates its relevance on patient care, especially in areas of limited financial resources.

Flow cytometric immunophenotyping including Bcl-2 detection on fine needle aspirates in the diagnosis of reactive lymphadenopathy and non-Hodgkin's lymphoma

BACKGROUND

Fine-needle aspiration (FNA) with immunophenotyping by immunocytochemistry (IC) on cytospins has recently received increased consideration in the diagnosis of lymphoma. The aim of our study was to establish the diagnostic value of a four-color flow cytometric (FCM) panel, including cytoplasmic Bcl-2, in cytologic diagnosis of malignant non-Hodgkin's lymphoma (NHL) and reactive lymphoid hyperplasia (RH).

METHODS

We investigated 424 FNAs from 396 patients. FCM panel included lambda/kappa/CD19/CD5, CD23/CD10/CD20/CD19, CD4/CD7/CD8/CD3 and Bcl-2/CD10/CD19/CD3 in fluorescein isothiocyanate, phycoerythrin, and peridinin chlorophyll protein or a tandem conjugate of R-phycoerythrin and indodicarbocyanine and allophycocyanin. Bcl-2 expression was evaluated separately for gated B and T cells.

RESULTS

In 97% of 172 RH samples, FCM was concordant with the diagnosis. FCM gave correct immunologic diagnosis in 95% of low-grade B-cell NHLs, 78% of high-grade B-cell NHLs, and 53% of T-cell lymphomas. Malignant B cells had higher Bcl-2 expression than did reactive B and T cells. This helped to establish a correct diagnosis especially in cases where no clear-cut monoclonality could be shown by kappa/lambda staining or where there was no expression of surface light chain. The highest Bcl-2 expression was found in follicular lymphomas.

CONCLUSION

Our FCM panel allowed precise classification of NHL in FNA material in 89.5% of all samples. Bcl-2 staining can be recommended for primary differentiation between reactive hyperplasia and NHL.

Fine-needle cytology and flow cytometry immunophenotyping and subclassification of non-Hodgkin lymphoma: a critical review of 307 cases with technical suggestions

BACKGROUND

Flow cytometry (FC) is a useful adjunct to fine-needle aspiration cytology (FNC) in evaluating lymphoproliferative disorders. The authors present a critical review of 307 lymph nodal and extra lymph nodal lymphoproliferative disorders that were diagnosed with FNC and FC.

METHODS

FC was performed over a 4-year period on 185 palpable and 122 impalpable lymph nodal and extra lymph nodal lymphoproliferative processes under ultrasound or computed tomography guidance. FC was performed using the following fluoresceinated antibodies: CD3, CD4/CD8, CD2/CD7/CD3, CD5/CD10/CD19, CD19/kappa/lambda, FMC7/CD23/CD19, CD38/CD56/CD19, and bcl-2. The series included 15 inadequate, 10 suspicious, and 135 benign reactive hyperplasias (BRHs); 70 primary non-Hodgkin lymphomas (NHLs), and 77 recurrent NHLs (rNHLs). FC/FNC diagnoses of suspicious, NHL, and rNHL were controlled either histologically or clinically or by the interphase fluorescence in situ hybridization demonstration of t(11;14)(q13;q32) in two cases of mantle cell lymphoma. BRHs were controlled by follow-up. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the FC/FNC diagnoses of NHL, rNHL, and BRH were calculated as well as the identification of specific subtypes among the small- and medium-sized cells.

RESULTS

Statistical analysis showed 93% sensitivity, 100% specificity, 100% PPV, and 91% NPV in NHL, rNHL, and BRH discrimination. The subclassification of small cell and medium-sized NHLs showed 63% sensitivity, 88% specificity, 95% PPV, and 37% NPV.

CONCLUSIONS

FC applied to FNC enhanced the precision of cytologic diagnosis in lymph nodal and extra lymph nodal lymphoproliferative disorders and allowed further subclassification in more than half of the cases, thus avoiding invasive surgical biopsies in many patients.

Role of fine-needle aspiration cytology in breast lymphoma

Lymphomas of the breast are rare and may mimic carcinoma clinically. We investigated the ability of fine-needle aspiration (FNA) biopsy combined with adjunctive flow cytometry (FC), immunofluorescence microscopy (IFM), and immunocytochemistry (ICH) to diagnose and eventually subclassify lymphomas of the breast according to the Revised European American Lymphoma/World Health Organization classification. We retrieved 21 breast aspirates from 19 patients with a cytologic diagnosis of lymphoma or plasmacytoma over a 10-year period (1992-2002), excluding 98 benign intramammary lymph nodes and 1 atypical lymphohistiocytic proliferation (Rosai Dorfman disease). FC was performed in 15/21 aspirates, IFM in 1/21, ICH in 3/21. Histologic follow-up (HF) was obtained for 10 patients, most of them with primary lymphoma. For the remaining nine patients without HF, flow cytometric analysis, comparative morphology, or remission after chemotherapy regimens supported the cytologic diagnosis. Of 19 patients, 11 patients had a secondary lymphoma (SL) and 8 patients had a primary lymphoma (PL). FNA and FC/IFM/ICH classified 7/8 PLs as B-cell lymphomas and 1/8 PLs as plasmacytoma. However, FNA could only subclassify 3 of 8 PLs. FNA and/or FC subclassified accurately 10/11 SLs. All cases were accurately immunophenotyped as B-, T-cell non-Hodgkin's lymphomas or plasmacytoma. World Health Organization classification was achieved in 3/8 PLs (42%) and 10/11 SLs (91%; P = 0.04). Subclassification (which has an impact on long-term management and prognosis) was significantly better in SL, when a previous histologic diagnosis had already been made, when compared to PL, of which 5/8 cases (62.5%) could not be accurately classified.

Evaluation of interphase fluorescence in situ hybridization for the t(14;18)(q32;q21) translocation in the diagnosis of follicular lymphoma on fine-needle aspirates

BACKGROUND

Diagnosing lymphoproliferative disorders on fine-needle aspiration (FNA) can be challenging due to variable cellularity and lack of architecture. Ancillary studies often are required for diagnosis. Follicular lymphoma (FL) is characterized by a monoclonal B-cell proliferation with coexpression of CD19/CD10 and a t(14;18)(q32;q21) reciprocal translocation, resulting in the immunoglobulin heavy chain/BCL-2 fusion gene. These features also can be found, with much lower frequency, in diffuse large B-cell lymphoma (DLBCL) of follicle center cell origin. The objective of the current study was to compare the accuracy in detecting FL and DLBCL of follicle center cell origin by interphase fluorescence in situ hybridization (I-FISH) versus flow cytometry immunophenotyping (FCM) on FNAs.

METHODS

Concurrent testing by FISH for t(14;18)(q32;q21) and FCM was performed on 84 FNAs, including 40 FLs and 44 non-FLs (de novo DLBCLs, mantle cell lymphomas, small lymphocytic lymphomas/chronic lymphocytic leukemias [SLLs/CLLs], small B-cell lymphomas, and reactive lymphoid hyperplasias). The final diagnosis was rendered based on the combined information from cytomorphology, FCM, FISH, immunocytochemical staining for Ki-67, monoclonality for kappa and lambda light chains, and, if available, corresponding tissue biopsy, cytogenetic analysis, and polymerase chain reaction analysis.

RESULTS

Among 40 FLs, FISH produced positive results for the t(14;18) translocation in 85.0%, negative results in 7.5%, and insufficient results in 7.5%; whereas, with FCM, 75% of cases exhibited a CD19-positive (CD19+)/CD10+ population (28 monoclonal, 2 nonclonal), 12.5% of cases exhibited a CD19+/CD10-negative population (3 monoclonal, 2 nonclonal), and 12.5% of cases were insufficient. All of nonclonal results from FCM and all of the insufficient results from FCM analysis exhibited unequivocal t(14;18) translocation by FISH. In contrast, the three negative results and the three insufficient results from FISH were monoclonal and CD19+/CD10+ on FCM. The results from FISH and FCM were concordant in 75% cases. Of 44 non-FLs, FISH produced positive results for the t(14;18) translocation in 5 DLBCLs and 2 SLLs/CLLs. The latter showed single fusion signals just above the cutoff level. All cases in the non-FL group that failed to show clonality or had insufficient results from FCM were DLBCLs. Among 17 DLBCLs, FISH detected a t(14;18) translocation in 29.4%, whereas FCM demonstrated a CD19+/CD10+ population in 23.5%.

CONCLUSIONS

I-FISH for the t(14;18)(q32;q21) translocation provided high overall accuracy in detecting FLs on FNAs. This test can be used for diagnosing or monitoring FL on FNAs when cellularity is limited or when FCM results are noncontributory. For detecting a follicle center cell origin in DLBCLs, I-FISH for the t(14;18) translocation appeared to be slightly more sensitive than FCM for the CD19+/CD10+ immunophenotype.