Application of mid-infrared microscopic imaging for the diagnosis and classification of human lymphomas

Mid-infrared (MIR) microscopic imaging of indolent and aggressive lymphomas was performed including formalin-fixed and paraffin-embedded samples of six follicular lymphomas and 12 diffuse large B-cell-lymphomas as well as reactive lymph nodes to investigate benefits and challenges for lymphoma diagnosis. MIR images were compared to defined pathological characteristics such as indolent versus aggressive versus reactive, germinal centre versus activated cell-of-origin (COO) subtypes, or a low versus a high proliferative index and level of PD-L1 expression. We demonstrated that MIR microscopic imaging can differentiate between reactive lymph nodes, indolent and aggressive lymphoma samples. Also, it has potential to be used in the subtyping of lymphomas, as shown with the differentiation between COO subtypes, the level of proliferation and PD-L1 expression. MIR microscopic imaging is a promising tool for diagnosis and subtyping of lymphoma and further evaluation is needed to fully explore the advantages and disadvantages of this method for pathological diagnosis.     

Fine needle aspiration cytodiagnosis of Hodgkin's disease and its subtypes. I. Scope and limitations

The fine needle aspiration (FNA) smears and paraffin-embedded sections from 89 cases with a cytologic and histologic diagnosis of Hodgkin's disease (HD) and 27 cases with minor or major cytohistologic discrepancies were reviewed. The accuracy of the initial cytologic study was found to be 91.8% for diagnosing HD and 58.1% for classifying its subtypes. Following review, 87 of the 89 agreement cases remained classified as HD. Of the 27 cases with initial cytohistologic discrepancies, 12 were classified as HD and 10 were categorized as lymphocytic or non-Hodgkin's lymphoma by both cytology and histology upon review. Following review, the accuracy of FNA cytology for the diagnosis of HD improved to 98.0%, with 71.4% correct subtyping. The greatest limitation of cytologic subtyping was in cases of nodular sclerotic HD: only 3 of 17 cases could be subtyped even after review. The cytomorphologic features of the HD subtypes are described, and the difficulties encountered in the cytodiagnosis of HD are discussed at length. The results of this study indicate that FNA cytology is a useful tool not only for the diagnosis of HD, but also for its subtyping.     

The biological markers of non-Hodgkin's lymphomas: their role in diagnosis, prognostic assessment and therapeutic strategy

The biological markers of non-Hodgkin's lymphomas (NHL) are distinguished in three categories: serological, immunophenotypic, and molecular markers. The clinical importance of biological markers in NHL is based on their support of morphologic diagnosis, their role in staging and prognostic assessment, and their contribution to monitoring minimal residual disease (MRD). The most important serological markers reflect the tumor load (beta-2 microglobulin, beta 2-M), proliferative activity (lactic dehydrogenase, LDH), and invasive potential of lymphomas (CA 125). LDH and beta 2-M are included as important prognostic parameters in widely used staging systems. Immunophenotypic analysis identifies specific markers of lineage (B or T-cells), maturation level, cell proliferation, and clonality. Results of immunophenotyping are particularly useful in low to intermediate-grade NHLs to support the morphologic diagnosis and facilitate the detection of MRD after treatment. The molecular markers are genetic lesions involved in the pathogenesis of some categories of NHL. Their use as markers for diagnosis is justified by the selective association with specific lymphoma categories: follicular, mantle cell, diffuse large cell, and anaplastic large cell lymphomas. Molecular lesions are the most specific and sensitive markers for evaluating MRD. Today the biological markers of NHL are widely employed for diagnosis, staging, and prognostic assessment. Their systematic use may complement clinical parameters in the stratification of NHL patients, who may thus become candidates for treatments of different intensity. The detection of MRD after first-line treatment identifies patients at high risk of relapse who require additional therapy to cure their disease.     

Diagnosis of lymphoma by image-guided needle biopsies: fine needle aspiration biopsy, core biopsy or both?

OBJECTIVE: To determine whether or not concurrent core biopsy adds to results obtained from image-guided fine needle aspiration biopsy (FNAB) in cases of lymphoma. STUDY DESIGN: Twenty-eight FNABs of lymphomas with adjuvant flow cytometry (FC) and concurrent core biopsy were evaluated retrospectively. In each case, completeness of diagnosis by FNAB, including phenotyping and grading, where appropriate, was reviewed. The contribution of core biopsy to the diagnosis in cases where FNAB did not render a complete diagnosis was assessed. Prognostic information not available from the FNAB but obtained from the core biopsy was also evaluated. RESULTS: FNAB with adjuvant FC gave a complete diagnosis, including phenotype and grade, where applicable, in 23 of 28 cases (82%). Core biopsy added to the diagnosis in 3 cases. In 1 case, large B-cell lymphoma was diagnosed on core biopsy when FNAB was unsatisfactory. In the other 2 cases, grade of follicle center cell lymphoma was higher on core biopsy than on FNAB. The addition of the information obtained by core biopsy to that obtained by FNAB raised the diagnostic accuracy to 93%. Core biopsy was used to assess nodularity, which could not be determined on FNAB. Core biopsy was also used to assess prognostic markers by immunohistochemistry (Ki-67 and p53); they were not available with FC. This was done in 11 cases when requested by the oncologist. CONCLUSION: FNAB with adjuvant FC is a useful technique for diagnosing and subtyping lymphomas. However, diagnosis and subclassification are often insufficient. Core biopsy material provides opportunity for obtaining additional diagnostic and prognostic information that may not be easily derived from the FNAB. This allows optimal treatment planning in patients for whom excisional biopsy is contraindicated.     

Role of molecular markers in diagnosis and prognosis of renal cell carcinoma

It has been demonstrated that different renal cell neoplasms have characteristic morphologic and genetic features. Histologic subtyping of renal epithelial neoplasms has been shown to be of prognostic value; therefore they must be correctly classified. Although adequate sampling and a good understanding of the morphologic features usually minimize diagnostic errors, the use of immunohistochemical and chromosomal analysis on formalin-fixed, paraffin-embedded tissues can be necessary. These techniques can facilitate diagnosis on small biopsies, which are increasingly obtained from renal masses. An immunohistochemical panel including CD10, parvalbumin, AMACR, CK7 and S100A1 seems the most promising; fluorescence in situ hybridization analysis using centromeric probes to evaluate the gains and losses of the chromosomes can be helpful in selected cases. A wide variety of molecular markers have been examined, but further research is required to prove their value as prognostic tools.     

Role of fine needle aspiration cytology in nodular sclerosis variant of Hodgkin's lymphoma

OBJECTIVE: To assess the efficacy of fine needle aspiration cytology (FNAC) in the diagnosis of nodular sclerosis variant of Hodgkin's lymphoma (NSHL) and to analyze cytologic features that could help in subtyping a case of Hodgkin's lymphoma into this variant. STUDY DESIGN: FNAC smears of 18 histopathologically proven cases of NSHL were analyzed for a variety of features. RESULTS: On initial cytologic assessment, 14 of 18 cases were diagnosed as Hodgkin's lymphoma. No further subtyping was performed. In this retrospective analysis it was possible to revise the diagnosis in the remaining 4 cases. Of the various cytologic features analyzed, presence of numerous lacunar-type cells along with fibroblasts and collagenous material were useful pointers toward a diagnosis of nodular sclerosis variant. Fibroblasts were seen in 83.33%, collagenous material in 27.77% and numerous lacunar cells in 77.77%. CONCLUSION: Subtyping of NSHL based on cytologic features alone has been a matter of debate for a long time. Of the various subtypes, nodular sclerosis poses the greatest diagnostic difficulty. Though certain cytologic features may help in suggesting a diagnosis of nodular sclerosis variant, the primary role of fine needle aspiration is to diagnose a case of Hodgkin's lymphoma as such and advise histopathologic examination for further categorization.     

非何杰金氏淋巴瘤在石蜡切片的免疫表型研究

用单克隆抗体ＬＣＡ,ＵＣＨＬ１,ＭＴ１,ＭＢ１,ＭＢ２,ＬＮ１和ＬＮ２对６５例非何杰金氏淋巴瘤常规福尔马林固定石蜡包埋组织切片作免疫表型研究。证实Ｂ细胞性淋巴瘤５０例（７７％）。Ｔ细胞性淋巴瘤１１例（１７％）（４例染色不良,未能分型）。根据国际工作分类,本组Ｔ细胞淋巴瘤所占比例分别是１１％,２７％和１３％。全部病例中ＬＣＡ阳性率９７％。Ｔ细胞抗体ＵＣＨＬ;阳性率（９１％）明显高于ＭＴ１（７３％）,且与Ｂ淋巴细胞无交叉反应。４种Ｂ细胞抗体阳性率分别为ＬＮ。（９６％）,ＭＢ２（９４％）,ＬＮ１（８６％）,ＭＢ１（８４％）。ＬＮ２和ＬＮ１对源于滤泡中心细胞淋巴瘤有更强的反应。研究结果表明上述单克隆抗体可有效用于非何杰金氏淋巴瘤石蜡切片的免疫组织化学标记,合理选用单克隆抗体有助于进行免疫学分型。     

Fine needle aspiration of metastatic and hematologic malignancies clinically mimicking pancreatic carcinoma.

The fine needle aspiration (FNA) cytology findings in 19 cases of hematopoietic and metastatic neoplasms that radiographically mimicked primary pancreatic carcinoma are reported. These cases represented 11% of 176 malignant diagnoses in a series of 304 pancreatic FNAs. The cytologic diagnoses included 7 non-Hodgkin's lymphomas, 2 Hodgkin's lymphomas, 6 small cell carcinomas (4 lung, 1 gallbladder, 1 skin), 3 squamous cell carcinomas (2 cervix, 1 esophagus) and 1 hepatocellular carcinoma. In six cases the pancreatic lesion was the initial presentation of malignant disease. These included five lymphomas, which probably involved peripancreatic lymph nodes, and a metastatic small cell carcinoma of pulmonary origin. Recognition of unusual morphologic features of pancreatic carcinoma raised the possibility of extrapancreatic malignancies. Electron microscopy and immunocytochemistry performed on FNA specimens were helpful in selected cases. The FNA diagnosis of hematopoietic and metastatic neoplasms that clinically mimic pancreatic carcinoma prompts appropriate clinical studies and treatment and eliminates the need for open pancreatic biopsy and/or resection.     

Serotypes and subtypes of Neisseria meningitidis serogroup B strains associated with meningococcal disease in Canada, 1977-1989

Typing of Neisseria meningitidis serogroup B disease isolates was carried out using a panel of serotype-and subtype-specific monoclonal antibodies (MAbs) in enzyme-linked immunosorbent assays (ELISA). Three hundred and sixty-two strains isolated from 1977 to 1986 were typed using five serotyping and seven subtyping reagents and outer membrane vesicles as antigens. Serotype 2b accounted for 30% of the disease isolates. The most common subtype was P1.2, which occurred on 18.5% of all strains or 48.6% of the serotype 2b strains. Of the 362 strains typed, 135 (37.3%) were serotyped and 122 (33.7%) were subtyped. Overall, 185 (51.1%) of the strains could be assigned a serotype and (or) subtype. Strains (221) isolated during the years 1987-1989 were typed using a panel of 6 serotyping and 12 subtyping reagents by whole-cell ELISA. Strains of serotypes 4 (21.7%) and 15 (20.8%) were the most common and carried a wide variety of subtypes. The most common subtypes were P1.2 (11.8%) and P1.16 (9.5%). Of the 221 strains analyzed, 132 (59.7%) were assigned a serotype and 123 (55.7%) a subtype and with all 18 MAbs, 192 (86.9%) of the strains were serotyped and (or) subtyped. Two different MAbs to the four epitopes 2a, 15, P1.2, and P1.16 gave discordant reactions of 0.3, 6.6, 2.6, and 2.2%, respectively, when used to analyze over 300 strains of N. meningitidis.     

乳腺恶性血液病的病理类型、临床特点及生存分析

目的:探讨乳腺恶性血液病的病理分型、患者的临床特征及预后。方法:回顾性分析2014年1月至2019年1月空军军医大学西京医院收治的33例乳腺恶性血液病患者的病理分型、临床特征及预后。结果:33例患者中,32例为女性,1例为男性,平均年龄为45.5岁(12-78岁)。经病理确诊29例(29/33,87.9%)为非霍奇金淋巴瘤,其中弥漫大B细胞淋巴瘤(18/29,62.1%)最为常见,其次是NK/T细胞淋巴瘤(3/29,10.3%),B淋巴母细胞白血病/淋巴瘤(2/29,6.8%),而伯基特淋巴瘤、滤泡淋巴瘤、原发皮肤间变大细胞淋巴瘤各1例(1/29,3.4%),其余3例未进一步分型。此外,1例(1/33,3.0%)霍奇金淋巴瘤,3例(3/33,9.1%)急性白血病复发累及乳腺。原发性乳腺恶性血液病为19例(57.6%),继发性为14例(42.4%),病变主要累及右侧乳腺(18例,54.5%),其次为左侧(10例,30.3%),双侧均累及的为少数(5例,15.2%)。19例原发性乳腺恶性血液病均为淋巴瘤,与14例继发性乳腺恶性血液病相比,其血小板计数明显升高(P=0.004),β2-MG显著降低(P=0.049),B症状少(P=0.017),Ann Arbor分期主要为Ⅰ-Ⅱ期(P<0.01),骨髓受累少(P<0.01)等特点。生存分析提示原发性乳腺恶性血液病患者比继发性患者生存期更长(HR=9.846,P=0.002)。恶性血液病累及骨髓可导致生存期显著缩短(HR=6.434,P<0.01)。结论:乳腺恶性血液病患者以中年女性为主,原发性乳腺恶性血液病比继发性发病率高(分别为57.5%和42.5%),最常见的病理类型为弥漫大B细胞淋巴瘤,病变主要累及右侧乳腺。与继发性乳腺恶性血液病相比,原发性乳腺恶性血液病患者具有血小板计数相对更高,β2-MG水平更低,往往不伴B症状,Ann Arbor分期主要为Ⅰ-Ⅱ期,骨髓不受累,且生存期显著延长等特点。此外,恶性血液病累及骨髓提示预后不良。     

Cytodiagnosis of lymphoid proliferations by fine needle aspiration biopsy. Adjunctive value of flow cytometry

OBJECTIVE: To determine the accuracy of fine needle aspiration biopsy (FNAB) complemented by flow cytometry (FC) for the diagnosis of reactive and neoplastic lymphoid proliferations and subclassification of malignant lymphomas. STUDY DESIGN: Forty-one FNABs of lymphoid lesions on which FC had been performed were evaluated retrospectively. All cases were correlated with histology or clinical follow-up. RESULTS: Twelve FNABs were diagnosed as reactive. Eleven of the 12 were confirmed as reactive on follow-up. One was a case of posttransplant lymphoproliferative disorder. Twenty-five FNABs diagnosed as lymphoma were confirmed by histology. In 22 of these 25 cases, there was 100% correlation between the subclassification given on FNAB with FC and that given on histology. Two of the remaining cases, which were correctly called follicular center cell lymphoma, showed discrepancies in grading. One case called Hodgkin's disease on FNAB was T-cell lymphoma on histology. Of four FNABs given an inconclusive diagnosis, two were lymphoma on follow-up, and two were reactive. CONCLUSION: FNAB examination, when it includes immunophenotyping by FC, is a useful technique for distinguishing reactive lymphoid proliferations from malignant lymphomas and for the subclassification of lymphomas.     

Morphologic spectrum of papillary carcinoma of the thyroid: role of cytology in identifying the variants

OBJECTIVE: To evaluate the efficacy of fine needle aspiration cytology (FNAC) in the diagnosis of morphologic variants of papillary carcinoma of the thyroid (PCT) and to determine the reasons for misdiagnosis in discrepant cases on cytology. STUDY DESIGN: Fine needle aspiration smears from 158 histologically proven cases of PCT were blindly reviewed and an attempt made to subclassify them into different variants on the basis of various architectural and morphologic features. Cytohistologic correlation was performed to assess the efficacy of cytology in correctly identifying these variants. RESULTS: In cases with satisfactory aspirates, the diagnosis of papillary carcinoma was correctly made in 112 of 139 (80.5%) histologically proven cases of PCT. Subclassification was correct in 87 of 96 (90.6%) cases of classic papillary carcinoma and in 25 of 43 (58.1%) of the other variants of PCT with adequate aspirates. Cytohistologic agreement was 100% in columnar cell variant (CCV) and high grade variant (HGV). Although there was overlap in the morphologic features of tall cell variant (TCV) and Hürthle cell variant, cytology correctly identified 60% and 76.4% of these cases, respectively. The accuracy of cytology was limited in diagnosing follicular variant as only 50% of these cases could be correctly typed on cytology. Nodular fascitis-like stroma and diffuse sclerosis variants could not be diagnosed on cytology. CONCLUSION: Though FNAC is of limited value in typing the variants of PCT due to overlapping morphologic features, it can provide clues to the diagnosis in certain aggressive variants such as TCV, CCV and HGV. Early diagnosis in these cases can assist clinicians with management.     

Cytologic diagnosis and subtyping of rhabdomyosarcoma

atahan s,., aksu ö. and ekinci c. (1998) Cytopathology 9, 389–397
Cytologic diagnosis and subtyping of rhabdomyosarcoma
We reviewed the cytological findings of 38 cases of rhabdomyosarcoma (RMS) with histological confirmation performed during a period of 15 years and proposed a morphological subtyping based on the most prominent cytologic features. Seventeen of these cases were alveolar, 14 cases embryonal, and seven botryoid subtypes. From these cases, a total of 43 samples, of which 37 were fine needle aspiration (FNA) biopsies and six were touch imprints, were evaluated. Detailed cellular features were identified which enabled differentiation into histological subtypes. In the alveolar RMSs, most tumour cells were small and lymphocyte-like, having finely granular chromatin. The finding of cells with more abundant cytoplasm, eccentrically located nuclei and bi/multinucleated tumour cells in a background of mucosubstance helped in the differential diagnosis. Two cell types, including large, tadpole or ribbon-shaped tumour cells and small, round cells with scant cytoplasm, were seen in embryonal RMSs. In botryoid RMSs, a cell type with tightly grouped nuclei within elongated cytoplasm similar to a myotubular structure was observed in addition to the two cell types of embryonal RMSs. We conclude that with experience it will be possible to subtype these tumours by cytologic examination alone.     

Fine needle aspiration cytodiagnosis of Hodgkin's disease and its subtypes. II. Subtyping by differential cell counts

Differential cell counts were performed on fine needle aspiration (FNA) smears from 96 cytologically diagnosed and subsequently biopsy-proven cases of Hodgkin's disease (HD). Reed-Sternberg cells and Hodgkin cells showed a definitely increasing trend in three major HD subtypes (as diagnosed on the smears): lymphocytic predominance (LP), mixed cellularity (MC) and lymphocytic depletion (LD). Lymphocytes, on the other hand, showed a decreasing trend between these subtypes. The differences in the percentages of Hodgkin cells, Reed-Sternberg cells and lymphocytes were highly significant (P less than .001). No trends (increasing or decreasing) were observed in the smear content of other reactive components (non-neoplastic histiocytes, eosinophils, plasma cells and neutrophils). In 88.0% to 95.0% of the cytologically diagnosed cases of LP, MC and LD subtypes, the percentages of Hodgkin cells plus Reed-Sternberg cells fell within a distinct range: less than 1.5% for LP, greater than or equal to 1.5% to less than 7.5% for MC and greater than or equal to 7.5% for LD. Analysis of the data based on histopathologic subtyping of the cases showed similar significant trends in the proportions of Hodgkin cells, Reed-Sternberg cells and lymphocytes, with 70.0% to 80.0% of the LP, MC and LD subtype cases within these ranges. These results demonstrate the validity of the subjective subtyping of HD on FNA smears in most cases.     

Cytomorphology and immunocytochemistry of fine needle aspirates from blastic non-Hodgkin's lymphomas

Fine needle aspirates from 54 consecutive patients with primary or recurrent blastic (high-grade malignant) non-Hodgkin's lymphomas (NHLs) were analyzed by cytomorphology and immunocytochemistry. The cytologic diagnoses induced follicular center-cell-derived (centroblastic or anaplastic centrocytic) lymphoma (31 cases), immunoblastic lymphoma (11 cases), lymphoblastic lymphoma (9 cases) and histiocytic lymphoma (3 cases). Immunocytochemistry showed a B-cell phenotype of the neoplastic lymphocytes in all lymphoblastic lymphomas, 29 follicle center-cell lymphomas and 4 immunoblastic lymphomas. Four of the immunoblastic lymphomas were of T-cell origin while one case was not evaluable due to necrosis. A histiocytic origin was confirmed in two of the three cases that had a cytologic diagnosis of histiocytic lymphoma; the third case was shown by immunocytochemistry to be a true Ki-1-positive large cell lymphoma. Histologic and immunohistochemical analysis were performed on surgical biopsies from 18 patients. The results were in agreement with those on the fine needle aspiration (FNA) material in 14 cases. Three lymphomas could be phenotyped on aspirated material while marker studies on excised material were inconclusive. One lymph node aspirate contained mostly necrotic cells, which were unsatisfactory for adequate immunocytochemistry. However, sections from a removed tonsil from the same patient could be used for conclusive histology and phenotyping. In conclusion, the high diagnostic accuracy of combined cytomorphologic and immunocytochemical assessment of FNA samples validates the use of the technique in the diagnostic work-up of blastic (high-grade malignant) NHLs. In fact, the diagnostic accuracy seems so high that the technique can safely be used in the final diagnosis of blastic NHLs.     

Pleural effusions in non-Hodgkin's lymphoma. A cytomorphologic, cytochemical and immunologic study

Review of the records of 243 cases of cytologically diagnosed non-Hodgkin's lymphomas (NHL) revealed pleural effusions in 21 (8.6%). Cytologic examination of pleural fluid was done in 17 cases, of which 16 were reported as positive. Cytologic examination was supplemented with cytochemical staining (acid phosphatase, alpha naphthyl acetate esterase and periodic-acid-Schiff reactions) and E-rosetting studies in 12 cases. Of the 16 positive cases, 11 were malignant lymphomas consisting of convoluted lymphocytes. Acute lymphatic leukemia of the prothymocytic type (T-ALL) and chronic lymphocytic leukemia of the T-cell type (T-CLL) comprised one case each, and there were three cases of follicular center cell lymphomas, two of the cleaved-cell type and one of the Burkitt-type. Comparison of the cytomorphology of the tumor cells in the pleural effusion with those in fine needle aspiration smears from the solid tumors in 14 cases showed an identical appearance in 13 cases; in one, the Burkitt-type lymphoma, the cells were larger and more pleomorphic in the pleural effusion. This study indicates that the cytologic diagnosis and categorization of NHL of the convoluted-cell type is greatly enhanced by the study of neoplastic lymphocytes in a pleural effusion.     

Value of image-guided needle aspiration cytology in the assessment of pelvic and retroperitoneal masses. A study of 112 cases

OBJECTIVE: To evaluate the diagnostic value of the noninvasive method of image-guided needle aspiration cytology (NAC) in the assessment of radiologically detected pelvic and retroperitoneal space-occupying lesions (excluding the pancreas, kidney and adrenal). STUDY DESIGN: NAC was performed under computed tomographic or ultrasound guidance on 112 patients suspected of having a pelvic or retroperitoneal mass. Cytologic examination was performed on site after staining smears with the Papanicolaou method. In addition, air-dried smears, fixed smears, filter preparations from needle washings and cell blocks were studied. The NAC diagnosis was supported by examining cell blocks; further support was obtained with a tissue biopsy in some cases. Additionally, pertinent immunoperoxidase and/or histochemical studies were done. RESULTS: Eighteen cases were diagnosed as inflammatory lesions, 17 cases consisted of normal cellular elements, and 12 cases showed scanty material and were considered unsatisfactory/inadequate for a diagnosis. Five cases were suspicious for malignancy, and in 39 cases metastatic tumors were diagnosed from a previously known primary. Thirteen cases were diagnosed as lymphoma, and in 8 cases a diagnosis of soft tissue sarcoma was made. There were no false positive diagnoses of malignancy. Cell block preparations and immunohistochemistry were helpful with tumor typing, although lymphoma subtyping and soft tissue tumor typing generally required open biopsy. CONCLUSION: NAC, as the first-line investigation, is not only useful in the diagnosis of space-occupying lesions of the pelvic and retroperitoneal region but can also help in choosing appropriate management. The technique is most useful in diagnosing metastases but is also helpful in excluding malignancy in some cases and in suggesting diagnoses of lymphomas and soft tissue tumors.     

Flow cytometry as an accurate tool to complement fine needle aspiration cytology in the diagnosis of low grade malignant lymphomas

S. Schmid, M. Tinguely, P. Cione, H. Moch and B. Bode
Flow cytometry as an accurate tool to complement fine needle aspiration cytology in the diagnosis of low grade malignant lymphomas Objective: Diagnosis of low grade non‐Hodgkin B‐cell lymphomas on cytological material may be problematic and in the past frequently required lymph node excision. We analysed our experience of the value of flow cytometry (FC) as an additional tool for the diagnosis of lymphoproliferative processes in the setting of a university cytology division with a busy fine needle cytology service. Methods: Consecutive cytological specimens with FC over a period of 3 years were retrospectively analysed and correlated with histology and follow‐up if available. FC was performed with the following antibodies: CD3, CD4, CD8, CD2, CD7, CD19, CD5, CD10, CD23, lambda and kappa chains. Results: Of 299 probes (273 fine needle aspirations and 26 fluids from 285 patients), 179 cases (60%) were diagnosed as reactive, 91 cases (30%) as malignant or suspicious and 29 cases (10%) as inconclusive. The results of histological examination of the lymph nodes were available in 41 of 91 (45%) malignant or suspicious cases and in 13 of 179 (7%) reactive cytological diagnoses. Cytologically diagnosed malignancy was confirmed in all histologically examined cases. In 12 of 13 reactive cytological cases (92%), a benign process was diagnosed histologically. In 34 of 299 cases (11%) additional molecular investigations of B‐cell clonality or specific translocations were performed. The lymphomas most frequently diagnosed were follicular lymphoma and lymphocytic lymphoma, followed by mantle cell and marginal zone lymphomas. Correlation with histology showed a sensitivity of 98% and a specificity of 100% for cytology in our series. Conclusions: FC is an important additional tool in the cytological diagnosis of lymphoproliferative disorders. The combined approach has a high diagnostic value that allows a reliable subclassification of low grade B‐cell non‐Hodgkin lymphomas.