Grading follicular lymphoma on fine needle aspiration specimens. Comparison with proliferative index by DNA image analysis and Ki-67 labeling index

Assessment of Ki-67 Proliferative Index in Cytological Samples of Nodal B-Cell Lymphomas

BACKGROUND

The Ki-67 proliferative index (PI) is part of the diagnosis of nodal B-cell lymphoma (nBCL), but its determination in cytological samples is not standardized. We aimed to establish an approach for the accurate determination of the Ki-67 PI in cytological slides to differentiate between indolent and aggressive nBCLs.

METHODS

Patients diagnosed with nBCL by fine-needle aspiration biopsy and subsequent excision biopsy were included. Cell suspensions were prepared from biopsy samples for CD3/Ki-67 double immunocytochemical staining and flow-cytometric verification of lymphoma B-cell counts. The Ki-67 PI was assessed by manual counting and eyeballing in cytology and eyeballing in histology. The cut-off values for the differentiation between aggressive and indolent lymphomas were determined for each method.

RESULTS

A strong correlation between manual and flow-cytometric counting of lymphoma B cells was confirmed (interclass correlation coefficient (IC coef.) = 0.78). The correlation of the Ki-67 PI determined in cytological and histological slides was also strong (IC coef. > 0.80). Histologically, 55 cases were classified as indolent and 31 as aggressive nBCLs. KI-67 PI cut-off values of 28.5%, 27.5%, and 35.5% were established for manual counting and eyeballing in cytology and eyeballing in histology, respectively, with high sensitivity and specificity.

CONCLUSIONS

The Ki-67 PI, assessed by manual counting and eyeballing in cytological samples, accurately differentiates between indolent and aggressive nBCLs.

Lymph node FNA cytology: Diagnostic performance and clinical implications of proposed diagnostic categories

BACKGROUND

Despite widespread clinical use, lymph node fine-needle aspiration cytology (LN-FNAC) lacks universal acceptance for definitively diagnosing lymphomas. This is likely due to reports of lower diagnostic performance, inconsistent terminology use in cytopathology diagnostic reports, and only limited data on the clinical implications of LN-FNAC diagnoses. Recently, a uniform LN-FNAC cytopathological diagnostic reporting system was proposed (the Sydney System). This study evaluated LN-FNAC diagnostic performance and risks of malignancy associated with the proposed diagnostic categories.

METHODS

LN-FNAC specimens obtained in 2018-2019, with and without concurrent core biopsy, to evaluate for suspected lymphoma were analyzed (n = 349). LN-FNAC diagnoses were compared with final diagnoses obtained via subsequent tissue biopsy and/or clinical assessment.

RESULTS

The mean patient age was 57.6 years, and 41% were female. LN-FNAC was the initial diagnostic test in 223 (63.9%), and it was used to evaluate for recurrence in 126 (36.1%). LN-FNAC diagnosed 202 hematological malignancies (57.9%), 23 nonhematological malignancies (6.6%), and 124 reactive processes (35.5%). Subsequent tissue biopsy was performed in 42 (12%). The risks of malignancy per diagnostic category were as follows: inadequate, 58.3%; benign, 6.4%; atypical, 69.2%; suspicious, 96.7%; and malignant, 99.3%. LN-FNAC demonstrated up to 96.3% sensitivity, 91.91% specificity, and 87.35% accuracy. Optimal specimen quality and the use of intradepartmental consultation reduced diagnostic error rates in FNA cases without concurrent core biopsy (P = .029 and P = .0002 respectively).

CONCLUSIONS

LN-FNAC is accurate and reliable for the diagnosis of lymphoma. Inadequate LN-FNAC samples should be resampled due to a significant associated risk of lymphoma. The diagnostic performance of LN-FNAC may be improved with good specimen quality and reviews by multiple pathologists. Understanding the risks of malignancy associated with LN-FNAC diagnostic categories will help to guide optimal patient management.

Lymph node fine-needle cytology in the era of personalised medicine. Is there a role?

The 2016 World Health Organisation revised classification of lymphoma has sub-classified well-defined entities and added a number of provisional entities on the basis of new knowledge on genetic, epigenetics and phenotypical data; prognostic and predictive features are also part of this classification. New knowledge on well-defined entities further enlightens the mechanisms of lymphomagenesis, which are more complex and multifactorial than once believed. Therapies are also more complex because traditional clinical trials have been integrated with new drugs and compounds with unique mechanisms of actions against distinct molecular targets. As lymphoma acquires additional genetic and phenotypic features over the time, pathological assessment is also necessary. Histological evaluation and tissue collection by surgical biopsies are necessary for phenotypical and molecular purposes; however, these are demanding procedures for both the patient and the health care system. At the same time, the choice of the best treatment for a specific entity, in different phases and different patients requires information that may not be available when the biopsy is performed. Fine needle aspiration cytology (FNAC) is successfully used in lymph nodes (LNs) in combination with different ancillary techniques and might be used to assess the phenotypic and genetic profile of specific targets and to get key information for therapy, in different phases and stages of the disease, with the option to re-check the same target over time, without surgical excision. This brief review describes LN-FNAC diagnostic criteria, current therapies for lymphomas and the potential role of LN-FNAC in selecting non-Hodgkin lymphomas patients for specific targeted treatments.

Cytologic features, immunocytochemical findings, and DNA ploidy in four rare cases of epithelioid hemangioendothelioma involving effusions

BACKGROUND

Epithelioid hemangioendothelioma (EHE) involving serous effusion is extremely rare, and the diagnosis can be challenging. DNA ploidy quantitation of EHE in effusion fluids has not been previously described in the English-language literature.

METHODS

Specimens of cytological diagnosed with EHE in effusion fluids between 2002 and 2009 were retrieved from the pathology files at MD Anderson Cancer Center. A total of four cases of EHE involving or arising from effusion fluids were found, and we reviewed cytospin, smears, cell block sections, and immunostained slides. DNA image analysis for ploidy and proliferation evaluation was performed on a destained, papanicolaou-stained slide from each case.

RESULTS

The tumor cells were epithelioid with prominent cytoplasmic vacuolization and intracytoplasmic inclusions, which could resemble reactive mesothelial cells, mesothelioma, or adenocarcinoma. The tumor cells were positive for endothelial markers. DNA image analysis in three of the four cases revealed predominantly diploid and tetraploid subpopulations, with few aneuploid cells and fairly low proliferation indices, and these patients had fairly prolonged survival.

CONCLUSIONS

DNA image analysis is useful for differentiating EHE from reactive mesothelial cells and high-grade carcinoma. For accurate diagnosis of EHE in effusion fluids, cytologic features should be considered together with clinical history and ancillary studies.

Sensitivity of fine-needle aspiration biopsy for diagnosing and grading follicular lymphomas using a multiparameter approach in a cancer center

OBJECTIVES

The diagnosis and grading of follicular lymphomas (FLs) by fine-needle aspiration biopsy (FNAB) has not been systematically compared with core needle biopsy (CNB). We evaluated the sensitivity of FNAB in diagnosing and grading FLs using a multiparameter approach in a large cancer center.

METHODS

We retrospectively identified CNBs of lymph nodes diagnosed as FL that also had a concurrently acquired FNAB on the same site. The majority of cases had flow cytometric analysis and these results were available for interpretation of both the FNAB and CNB.

RESULTS

Out of 342 patients, CNB diagnoses included 291 (85%) low-grade (LG) FLs, 30 (9%) high-grade (HG) FLs, and 21 (6%) non-graded FLs/other. FNAB diagnoses included 194 (57%) LG FLs, 19 (6%) HG FLs, 93 (27%) non-graded FLs, 9 (3%) large B-cell lymphomas (LBCL) of follicle center origin, and 27 (7%) insufficient for diagnosis/other. Review of non-graded FLs showed 45% LG, 35% indeterminate due to polymorphous lymphoid cells with increased numbers of large cells, and 20% scant cellularity. Sensitivity of FNAB for diagnosing FL was 89%, and 66% for LG FL. The latter increased (94%), however, when grading was performed.

CONCLUSION

FNAB is highly sensitive for diagnosing FLs when cellular material for cytomorphology and flow cytometric analysis is obtained, and grading is feasible for most LG FLs. A subset of FLs composed of a polymorphous lymphoid population with increased numbers of large cells may be more difficult to grade, and HG FLs can be difficult to distinguish from CD10-positive diffuse LBCLs.

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.

From cytomorphology to molecular pathology: maximizing the value of cytology of lymphoproliferative disorders and soft tissue tumors

OBJECTIVES

The field of cytopathology has been rapidly advancing in the era of molecular pathology and personalized medicine. On-site cytologic evaluation for adequacy and triaging specimens for small core biopsy or fine-needle aspiration (FNA) are often required. Cytopathologists face the challenge of how to best triage small specimens for diagnosis, molecular testing, and personalized treatment. Owing to its minimally invasive nature, FNA alone or combined with core biopsy for lymphoproliferative disorders and soft tissue tumors has gained popularity.

METHODS

Literature review and author's institutional experience are used for this review article. This article will focus mainly on lymphoproliferative disorders and soft tissue tumors.

RESULTS

Evaluation combining cytomorphology, immunohistochemistry, and/or molecular pathology is often needed to accurately diagnose and classify lymphomas and soft tissue tumors. Many molecular tests have been performed on cytologic specimens, such as tests for BRAF and RET in thyroid FNA.

CONCLUSIONS

Molecular pathology has been widely integrated into conventional cytopathology for diagnosing lymphoproliferative disorders and soft tissue tumors, and the diagnostic value of FNA on those tumors has increased significantly. Cytology will play a more important role in the era of personalized medicine.

Fine-needle aspiration diagnosis of lymphomas with signet ring cell features: potential pitfalls and solutions

BACKGROUND

Lymphoma with signet ring cell features (LSF) is a rare morphologic variant of non-Hodgkin lymphoma. Although it has been well documented in the surgical pathology literature, to the best of the authors's knowledge, the features of LSF in fine-needle aspiration (FNA) samples have rarely been reported. An accurate cytologic diagnosis of LSF is of important therapeutic significance.

METHODS

The authors retrospectively reviewed 7 FNA cases of LSF for cytologic features, ancillary studies, corresponding histologic findings, and the patients' clinical and radiologic information to illustrate the diagnostic clues and potential pitfalls.

RESULTS

The final diagnoses, based on a multidisciplinary approach, were follicular lymphoma (5 patients), large B-cell lymphoma of follicular center cell origin (1 patient), and low-grade B-cell lymphoma with plasmacytoid features (1 patient). FNAs were obtained from both lymph node and extranodal sites. Common cytologic features included various percentages of signet ring cells in a background of nonvacuolated lymphomatous cells, lymphoglandular bodies, and cytoplasmic rings. The majority of signet ring cells contained a single, large, clear intracytoplasmic vacuole that pushed the nucleus laterally whereas fewer cells contained ≥ 2 vacuoles that indented the nucleus into a scalloped or stellate configuration. These cells resemble, to some degree, other lesions with signet ring cell features. One of the diagnostic clues of LSF was the similarity in nuclear details between signet ring cells and surrounding nonvacuolated lymphoid cells.

CONCLUSIONS

Familiarity with cytologic features, correlation with clinical/radiologic information, and ancillary studies are important for an accurate diagnosis of LSF and for distinguishing it from other lesions with signet ring cell features in FNA samples.

Classifying B-cell non-Hodgkin lymphoma by using MIB-1 proliferative index in fine-needle aspirates

BACKGROUND

MIB-1 proliferation index (PI) has proven helpful for diagnosis and prognosis in non-Hodgkin lymphomas (NHLs). However, validated cutoff values for use in fine-needle aspiration (FNA) samples are not available. We investigated MIB-1 immunocytochemistry as an ancillary technique for stratifying NHL and attempted to establish PI cutpoints in cytologic samples.

METHODS

B-cell NHL FNA cases with available cytospins (CS) MIB-1 immunocytochemistry results were included. Demographic, molecular, immunophenotyping and MIB-1 PI data were collected from cytologic reports. Cases were subtyped according to the current World Health Organization classification and separated into indolent, aggressive, and highly aggressive groups. Statistical analysis was performed with pairwise Wilcoxon rank sum test and linear discriminant analysis to suggest appropriate PI cutpoints.

RESULTS

Ninety-one NHL cases were subdivided in 56 (61.5%) indolent, 30 (33%) aggressive, and 5 (5.5%) highly aggressive lymphomas. The 3 groups had significantly different MIB-1 PIs from each other. Cutpoints were established for separating indolent (<38%), aggressive (> or =38% to < or =80.1%) and highly aggressive (>80.1%). The groups were adequately predicted in 76 cases (83.5%) using the cutpoints and 15 cases showed discrepant PIs.

CONCLUSIONS

MIB-1 immunohistochemistry on CS can help to stratify B-cell NHL and showed a significant increase in PI with tumor aggressiveness. Six misclassified cases had PIs close to the cutpoints. Discrepant MIB-1 PIs were related to dilution of positive cells by non-neoplastic lymphocytes and to the overlapping continuum of features between diffuse large B-cell lymphoma and Burkitt lymphoma. Validation of our approach in an unrelated, prospective dataset is required.

Clonal B-cell population in a reactive lymph node in acquired immunodeficiency syndrome

A 40-year-old female, HIV positive, stage C, since 4 years, complained of a right cervical lymph node swelling. Two years before, the patient had been diagnosed with follicular B-cell non-Hodgkin lymphoma (FL); she had been treated with four cycles of multiagent chemotherapy plus rituximab, the last cycle being administered 10 months before coming to our attention. An ultrasound (US) guided fine-needle cytology (FNC) showed an atypical lymphoid cell proliferation. The phenotype evidenced by flow cytometry (FC) analysis was D5: 10%, CD19: 49%, CD23: 10%, FMC7: 0%, CD10: 40%, CD10/19: 40%, lambda light chain 40%, kappa light chain 0%. FDG-positron emission tomography (PET/CT) scan showed positivity in the corresponding cervical area. Since low LDH values and a reduced lymph node size were observed, the lymph node was therefore excised; the histology revealed a reactive hyperplastic lymph node with florid follicular pattern. A subsequent PCR analysis, performed on DNA extracted from a whole histological section, did not evidence IgH rearrangement. The patient is currently undergoing strict clinical and instrumental follow-up, including PET every 3 months; after 13 months, she is alive without recurrence of lymphoma. Clonal B-cell populations in non-lymphomatous processes have been described in mucosa-associated lymphoid cell populations and reactive lymph nodes, and are considered non-malignant, antigen driven, proliferations of B-lymphocytes determined by an abnormal response to bacterial or viral antigen stimulation. The present case occurred in an HIV patient and was clinically complex because of the patient's history of FL. This experience suggests much attention in the evaluation of radiological, cytological, and FC data and in clinical correlation in patients suffering from autoimmune or immunodeficiency syndromes.

Immunocytochemical typing of primary tumors on fine-needle aspiration cytologies of lymph nodes

The aim of this study was to analyze the role of immunocytochemistry as an ancillary method on routine FNACs of enlarged lymph nodes, using different markers. In a validating cohort study all patients had confirmatory histological and/or clinical follow-up. 10 FNACs were analyzed for the differentiation of Non-Hodgkin Lymphoma (NHL) from metastatic carcinoma (MC), 30 cases to identify the sites of metastatic unknown primary tumors and 16 cases were checked to confirm clinical suspicion of a specific MC. Accuracy to differentiate NHL from MC was 100%, 92.3% to identify a primary tumor site of MC, and 100% to confirm a clinical suspicion of a specific MC. In 7 cases, the site of the primary tumor remained clinically unknown. Application of immunocytochemical markers on the same slide used for microscopic diagnosis is a useful tool in the routine assessment of FNACs of lymph nodes.

Cytomorphological and immunocytochemical study of non-Hodgkin's lymphoma in pleural effusion and ascitic fluid

INTRODUCTION

Non-Hodgkin's lymphoma (NHL) is often complicated by pleural effusion and ascites. The present study is an attempt to categorize the lymphomatous effusions according to the WHO classification, using archival material.

METHODS

May-Grünwald-Giemsa and Papanicolaou-stained smears of 31 lymphomatous effusion specimens were reviewed. Of these, detailed cytological assessment was done on 12 pleural effusions and ten ascitic fluid specimens from 22 patients using the WHO lymphoma classification system. Immunocytochemical studies were performed in 21 specimens.

RESULTS

Based on cytomorphological features, the 22 lymphomatous effusion specimens were categorized into lymphoplasmacytoid lymphoma (1), follicle centre cell (FCC) grade-1 (centrocytic) lymphoma (3), FCC grade-2 (centrocytic-centroblastic) lymphoma (3), FCC grade-3 (centroblastic) lymphoma (4), large cell immunoblastic lymphoma (4), lymphoblastic lymphoma (2), anaplastic large cell lymphoma (3) and miscellaneous types (2). Immunocytochemically, the lymphoma cells were T-cell (positive for CD3) and B-cell type (CD20 positive) in five and six cases respectively.

CONCLUSION

Cytological examination of pleural effusion and ascitic fluid samples, supported by immunocytochemical studies, may be useful for the classification of lymphomas under the WHO system.

Utility of SKP2 and MIB-1 in grading follicular lymphoma using quantitative imaging analysis

Follicular lymphoma is classified into grades (G)1, 2, and 3 based on the number of centroblasts in neoplastic follicles. However, the accuracy of manually counting these centroblasts is limited by certain cells (large centrocytes, follicular dendritic cells, and histiocytes) that could mimic centroblast morphology. The reproducibility of follicular lymphoma grading is dependent upon observer experience; therefore, significant variations occur. This study is to explore a more objective, reliable way of grading follicular lymphoma using a quantitative imaging system in conjunction with immunostains with antibodies to proliferation markers MIB-1 and S-phase kinase-associated protein 2 (SKP2). Fifty-eight follicular lymphomas (G1, n = 23; G2, n = 18; and G3, n = 17) were studied on formalin-fixed, paraffin-embedded sections. Positive nuclear staining of both Ki-67 and SKP2 was recorded using the quantitative Clarient ACIS II system (Aliso Viejo, CA, USA). Ten high-power fields (x400) from randomly selected neoplastic follicles were counted by a pathologist blinded to the previously assigned morphologic grade. The results show that the percentages of Ki-67+ and SKP2+ cells significantly differ among the different grades of follicular lymphoma. A higher grade of follicular lymphoma is associated with a higher percentage of Ki-67+ and SKP2+ cells. The overall SKP2+% cells are substantially lower than Ki-67+% cells in the same grade of follicular lymphoma. Statistical significance is observed in Ki-67+ cells between follicular lymphoma G1 and follicular lymphoma G3 and between G1 and G2. In contrast, statistical significance is noted in SKP2+% cells between follicular lymphoma G1 and follicular lymphoma G3 and between follicular lymphoma G2 and follicular lymphoma G3. The findings suggest that the SKP2 expression has better discrimination with grades of follicular lymphoma than Ki-67 expression. Compared with traditional methods, quantitation of SKP2 expression using a quantitative image analysis system might be a useful and objective approach in grading follicular lymphoma.

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.

Ki-67 proliferative marker in lymph node aspirates of patients with non-Hodgkin's lymphoma

Proliferative activity of lymphoma cells was tested by immunocytochemical staining with Ki-67 monoclonal antibody in 63 aspirates of peripheral lymph nodes sampled from patients suffering from non-Hodgkin's lymphoma. Referring to the dominant cell population in nodal aspirates, a rising trend of Ki-67 proliferative marker was noted from the small cells (X = 13.20) and small cells with notched nucleus (X = 43.52) and large cells (X = 79.47) with histopathologic equivalents corresponding to aggressive lymphoma. Statistical testing of the difference in the Ki-67 proliferative marker against demographic and clinical-laboratory characteristics of the studied patients revealed the levels of significance for the performance status, bone marrow infiltration, and albumin serum value. Correlation of cytomorphological and immunocytochemical results was tested against International Prognostic Index (IPI). Statistically significant correlation of Ki-67 with cytomorphology and REAL-immunocytochemical classification of lymphoma was confirmed, but not with the IPI index. In order to determine the prognostic importance of Ki-67 marker, the patients were classified into those with low Ki-67 (<20% of proliferating cells), mean proliferation index Ki-67 (range 20-59%), and high proliferative index Ki-67 (positive in over 60% of lymphoma cells). Testing Ki-67 with survival we have found that the low proliferative index was associated with the longest survival, median about 36 mo; for proliferative marker values ranging between 20 and 59%, the median survival was 30.4 mo; and survival of patients with the high proliferative index was only 12.9 mo.

Grading of follicular lymphoma using flow cytometry

BACKGROUND

The treatment and prognosis of follicular lymphoma (FL) is dependant on the grade of the disease. In the World Health Organization classification of lymphoma, grading of FL into low grade (1 and 2) and high grade (3) is recommended. Grading of FL is possible in excision biopsy; histological grading is subjective and inconsistent. Grading is extremely difficult in needle core biopsies and fine needle aspirates. We attempted to grade FL using flow cytometry (FCM) and CD19/ forward scatter.

MATERIALS AND METHODS

Cases of FL seen in our institution and submitted for FCM were evaluated for the percentage of cells detected beyond the 500-channel mark (on a 1024 scale) on a CD19/forward scatter dot plot. We hypothesized that these cells most likely represent centroblasts and their percentage would reflect the grade of the disease. Histological grading of the lymphoma on the open biopsies constituted the reference for FL grade.

RESULTS

Thirty-six cases of FL, including 22 males and 14 females, ranging in age from 19 to 92 years (median, 42 years), were studied. There were 17 cases of low grade (grade 1; n=10 and grade 2; n=7) and 19 cases of high grade (grade 3) FL. The percentage of cells identified beyond the 500-channel mark on CD19/forward scatter dot plot ranged from 0.12% to 12.55% (median, 4.9%) in low grade (grade 1 and 2) whereas the percentage of those cells in high grade FL ranged from 6.22% to 51.95% (median, 21%; P=0.00001).

CONCLUSION

Our findings suggest that using a CD19/forward scatter dot plot can help identify centroblasts in FL making grading possible on FCM, especially in small biopsies and fine needle aspirates.

The feasibility of gene expression profiling generated in fine-needle aspiration specimens from patients with follicular lymphoma and diffuse large B-cell lymphoma

Lymphoma of germinal center cell (GC) origin generally is an indolent malignancy that transforms progressively into a more aggressive disease. According to the World Health Organization classification, lymphomas of follicular center cell origin are classified as either large B-cell lymphoma (LBCL) or follicular lymphoma (FL). The authors tested the feasibility of performing gene expression profiling using amplified RNA from fine-needle aspirates (FNA) obtained from lymph nodes. Twenty-four samples from patients with a diagnosis of FL or LBCL were obtained after Institutional Review Board-approved informed consent was obtained. The diagnoses were confirmed by 2 pathologists and were classified into 2 groups (10 LBCL samples and 14 FL samples) by using conventional morphology and immunophenotyping. One hundred nanograms of total RNA were subjected to 2 cycles of standard, double-stranded complementary DNA synthesis and in vitro transcription for target amplification using a small-sample target-labeling protocol. The biotinylated cRNA from each sample was hybridized to gene chips. Gene expression profiling results were analyzed first by principal-component analysis (PCA) by using a list of 146 probe sets that represented 62 genes that are characteristic of an activated B-cell (ABC) signature or a GC signature. The analysis identified 5 LBCL samples with an ABC cell signature. Using a list of 207 probe sets that represented 113 genes involved in FL transformation, PCA analysis identified 2 overlapping clusters corresponding to FL and GC-diffuse LBCL. To improve this classification further, the authors generated a list of 72 genes that were expressed differentially between FL and GC-LBCL. Using this list of genes, PCA analysis demonstrated a clear separation between FL and GC-LBCL. However, five FL samples clustered as an intermediate group between FL and GC-DLBCL. These samples were characterized morphologically by a mixed cell pattern with relatively fewer large, noncleaved lymphocytes and more small, cleaved lymphocytes. The results support the feasibility of FNA-based transcription profiles in patients with FL or LBCL, which, in combination with morphology and immunophenotyping, can help in the subtyping of these entities.

Grading follicular lymphoma on fine-needle aspiration specimens-A practical approach

Fine-needle aspiration biopsy (FNA) is a useful tool for evaluating and staging follicular lymphoma (FL) without subjecting patients to multiple excisional biopsies. The relative lack of architecture in FNA is a limitation in grading FL. Recognizing the various cellular components in aspirates of FL, correlating with flow cytometry, using other ancillary tests, and preparing cell blocks can help overcome difficulties in the grading process. Understanding the clinical relevance of distinguishing the various grades of FL is important in determining whether an aspiration biopsy is adequate or whether additional sampling by surgical biopsy is indicated.

Best Practice No 185. Cytological and molecular diagnosis of lymphoma

With the advances in molecular pathology, the cell as a morphological and functional unit has become essential in the diagnosis of lymphoma. Conventional staining, preparation, and interpretation of cells, as seen in fine needle aspiration cytology (FNAC), often used as a first line investigation of lymphadenopathy, is being supplemented with an array of immunocytochemical and molecular analyses, aimed not only at a more precise disease definition, but also at recognising factors that can predict prognosis and response to treatment. Accepting the pitfalls of conventional cytomorphology, this review looks at molecular changes characteristic to particular lymphomas and explores the currently available technology for their detection, with particular reference to cytological material. Future protocols for the diagnosis and management of patients with lymphadenopathy should include FNAC as an initial investigation, followed by immunocytochemistry and molecular investigations. Tissue biopsy, the conventional method of diagnosis, may be avoided in selected cases.