Cell blocks in cytopathology: a review of preparative methods, utility in diagnosis and role in ancillary studies

Utility and performance of cell blocks in cerebrospinal fluid cytology: Experience at two teaching hospitals

BACKGROUND

Cytology cell blocks (CBs) are not routinely made for cerebrospinal fluid (CSF) specimens. The goal of this study was to identify when CSF CB preparation improves diagnostic performance.

MATERIALS AND METHODS

Under institutional review board approval, a retrospective review of CSF cytology cases was conducted at a tertiary university-based hospital and an affiliated county hospital. Patient history, CSF volume, final diagnosis, use of stains, and whether the CB was contributory was determined from the cytopathology report. CSF nucleated cell count data was obtained from the medical record.

RESULTS

A total of 69 CSF specimens with CBs from January 2006 to March 2023 were identified from 61 patients. The median CSF volume was 8 mL (interquartile range, 4-13 mL; range, 1-800 mL), with immunohistochemical stains performed on 29 (42%) cases. Per cytology report, CB was contributory in 23 cases (33%), not contributory in 34 cases (49%), and not discussed in 12 cases (17%). The median volume was 8 mL for cases in which CB was contributory, not contributory, or not discussed. There was no difference in average nucleated cell counts between cases in which CB was contributory versus not contributory (73.9 vs. 40.0, p = .175).

CONCLUSIONS

CBs for CSF samples were contributory in a subset (33%) of cases. The authors were unable to identify any specific pre-analytic factors, including specimen volume and average nucleated cell counts, for cases in which CB was contributory. Further evaluation is needed to identify if there are scenarios in which CSF CBs should be routinely prepared.

Rapid on-site evaluation and cell blocks: getting the most from the least invasive method in cytopathology

INTRODUCTION

Fine needle aspiration cytology (FNAC) sampling is a minimally invasive procedure done to identify the pathology behind superficial and deep-seated lesions. Rapid on-site evaluation (ROSE) can be an adjunct to the FNACs. Our study aimed to identify the role of ROSE in diagnostic adequacy and to check the benefit of cell block (CB)/cell buttons prepared from the ROSE samples.

MATERIAL AND METHODS

A prospective study was conducted where all patients referred for FNAC were included. ROSE using 1% aqueous toluidine blue stain and CB/cell button preparations were done for the identification of various cytological lesions.

RESULTS

Among 600 cases included in the study most common age group was third and fourth decades with a mean age of 41.6 years and M: F ratio of 1:1.7. Ultrasound-guided procedures were done in 20% of cases. CB preparation was available in 14% of cases. Most CBs were from the cases wherein ROSE was performed 81% (77 out of 86), with CB helping in making an accurate diagnosis in 17% of cases. Lymph nodes 26%, and thyroid 23% were the most common sites for sampling with the highest number of repeat procedures from non-ROSE cases (14%). The non-diagnostic rate for non-ROSE cases was 7.7% (23/300) even after the repeat procedures as compared to 1.3% (4/300) for ROSE. Three slides on average were consumed in ROSE-performed procedures, as compared to an average of 5 slides in non-ROSE. The average turnaround time was 1.7 days for non-ROSE cases and 1.05 for ROSE cases respectively. Cyto-histopathological correlation was available in 40% of cases with a sensitivity of 98.1%, specificity of 96.7%, positive predictive value of 90%, negative predictive value of 99.4%, and diagnostic accuracy of 97%. The correlation of CB, number of slides consumed, and turnaround time among the 2 groups were statistically significant (P value < 0.001).

CONCLUSIONS

ROSE is a method used to assess material aspirated at the time of FNAC procedures to determine the adequacy and to an extent to identify whether the lesion is neoplastic or non-neoplastic. CBs have helped in increasing diagnostic accuracy apart from the fact that the paraffin-embedded tissue material can be used for further studies.

Contemporary art of cell-block preparation: Overview

Cell blocks (CBs) are paraffin-embedded versions of cytology specimens. These versions are contrasted with tissues made from surgical pathology specimens of formalin-fixed paraffin-embedded (FFPE) tissue. CBs enable various elective ancillary studies of a range of specimens. These studies include the potential to perform molecular tests with the enhanced cytopathological interpretation. CBs are increasingly reported in cytology specimens. The enhanced role of CBs incorporates additives with new markers for immunohistochemistry (IHC), including the multicolored approach to IHC, and the subtractive coordinate immunoreactivity pattern. Even when archived material is retrospectively retrieved, CBs are a major tissue source for many supplementary studies. The CBs have been qualitatively and quantitatively improved. CBs are significant since they have increased molecular markers standardized on FFPE tissue. High-quality CBs can serve as useful additions to cytological smear preparations and touch imprint cytology. Most cytological specimens, such as fine-needle aspirations, cavitary effusion, washings, brushings, and gynecological and non-gynecological liquid specimens, may be used to produce CBs. This review deals with the CB-making process and discusses various historical limitations with an emphasis on recent advances.

Pulmonary squamous cell carcinoma and lymphoepithelial carcinoma - morphology, molecular characteristics and differential diagnosis

Squamous cell carcinoma (SCC) comprises one of the major groups of non-small-cell carcinoma of the lung, and is subtyped into keratinising, non-keratinising and basaloid SCC. SCC can readily be diagnosed using histomorphology alone in keratinising SCC. Confirmatory immunohistochemical analyses should always be applied in non-keratinising and basaloid tumours to exclude differential diagnoses, most prominently adenocarcinoma and high-grade neuroendocrine carcinoma, which may have important therapeutic consequences. According to the World Health Organisation (WHO) classification 2015, the diagnosis of SCC can be rendered in resections of morphologically ambiguous tumours with squamous immunophenotype. In biopsies and cytology preparations in the same setting the current guidelines propose a diagnosis of 'non-small-cell carcinoma, favour SCC' in TTF1-negative and p40-positive tumours to acknowledge a possible sampling bias and restrict extended immunohistochemical evaluation in order to preserve tissue for molecular testing. Most SCC feature a molecular 'tobacco-smoke signature' with enrichment in GG > TT mutations, in line with the strong epidemiological association of SCC with smoking. Targetable mutations are extremely rare but they do occur, in particular in younger and non- or light-smoking patients, warranting molecular investigations. Lymphoepithelial carcinoma (LEC) is a poorly differentiated SCC with a syncytial growth pattern and a usually prominent lymphoplasmacytic infiltrate and frequent Epstein-Barr virus (EBV) association. In this review, we describe the morphological and molecular characteristics of SCC and LEC and discuss the most pertinent differential diagnoses.

Role of cytoblock on pleural effusion for diagnosis of malignant disease

BACKGROUND

Thoracocentesis of pleural effusion is a simple technique for pleural fluid examination through cytology. In addition to cytological examination to assess the nature of pleural fluid content, we can also perform more detailed examinations through cytoblocks of residual fluid. These paraffin-embedded cytoblock samples are important because we can perform examinations as in other bioptic samples. In these samples, immunohistochemical and molecular analyses can be performed.

METHODS

Two hundred fifty-five cytological samples from patients with pleural effusion were examined. In cases in which the presence of malignant cells was identified in the cytological examination, as well as cases that were suspicious but not definitive for the presence of a malignant effusion, a cytoblock was prepared. Histological examination and immunohistochemical analysis were performed.

RESULTS

Among 255 cases with pleural effusion, 152 had the presence of malignant cells and 6 cases were suspicious, but uncertain for the presence of malignant cells, while 86 cases had inflammatory pleural effusion or other pathologies but were not malignant. After histological analysis of the cytoblock and immunohistochemical analysis, we identified 82 malignant tumors of the lung, 8 malignant tumors of the gastrointestinal tract, 15 malignant tumors of the breast, and 6 malignant tumors of the female genital tract, as well as 24 tumors of undetermined origin.

CONCLUSIONS

Cytoblocks are important for the diagnosis of the primary nature of malignant pleural effusions. The highest importance is primary lung tumors, as well as those tumors in which the primary site of the tumor cannot be determined clinically.

Quality of cell blocks prepared from residual pleural effusion and bronchial washing samples for immunocytochemistry

INTRODUCTION

Cell blocks (CBs) enable the long-term preservation of cytological samples. The aim of this study was to analyse the quality of CBs prepared from leftover fluid from lung adenocarcinoma pleural effusion samples and residual bronchial washing sediment for immunocytochemistry.

METHODS

The residual part of 455 lung adenocarcinoma pleural effusion samples and sediment from 384 bronchial washing samples were used to prepare CBs following the agarose method. The quality of CBs was evaluated based on the quantity of malignant cells in haematoxylin and eosin-stained slides and interpreted as optimal or insufficient for immunocytochemistry. Immunocytochemistry on CBs was performed using the Dako EnVision™ FLEX detection visualisation system. The CB results for TTF-1, ALK, and PD-L1 immunocytochemistry were compared with the corresponding cytological smears.

RESULTS

Among all CBs, 202 (44.4%) from leftover pleural effusion fluid and 85 (22.1%) from residual bronchial washing sediment had an optimal number of lung adenocarcinoma cells. Eight pleural effusion CBs were stained for TTF-1. Four pleural effusion and two bronchial washing CBs were stained for ALK and PD-L1. All tested pleural effusion CBs were confirmed positive for TTF-1 and negative for ALK. The PD-L1 tumour proportion score (TPS) was ≥ 50% in two pleural effusions. ALK was confirmed negative in bronchial washing CBs. One bronchial washing CB was interpreted as PD-L1-negative while the corresponding smear was positive (TPS ≥1%; 2%).

CONCLUSION

The CB results of TTF-1, ALK, and PD-L1 corresponded to the findings for the smears. The inclusion of CBs prepared from leftover fluid from pleural effusion samples and residual bronchial washing sediment in routine cytological practice could provide a source of high-quality material for immunocytochemistry in addition to smears and cytospins.

A Report of Two Cases of Malignant Tumor of the Maxillary Sinus Diagnosed Using Fine-Needle Aspiration Cytology

Primary and metastatic malignancies arising in the sinuses are rare and histologically diverse. The role of fine-needle aspiration cytology (FNAC) and the cytomorphologic characteristics of these tumors have not been specifically addressed. We described two cases of suspected malignant maxillary sinus tumors in 85- and 90-year-old patients with comorbid conditions, both of whom underwent tissue biopsies that failed to yield a definitive diagnosis. We performed FNAC after imaging confirmed that the malignant tumors were outside the maxillary sinus. The 85- and 90-year-old patients were diagnosed with squamous cell carcinoma (SCC) and adenocarcinoma, respectively. In the latter, the cell block method was used to prepare the specimen, rendering individual cells identifiable. Atypia of the histological structure was confirmed without the influence of cell duplication, a known weakness of FNAC. Thus, the diagnosis was made quickly. We believe that FNAC would be utilized more frequently for the definitive diagnosis of sinonasal tumors as the technique and diagnostic technology improve further.

A novel method for making cell blocks with higher cellular yield

INTRODUCTION

Cytopathology is an important part of pathology that is used to diagnose disease on the cellular level. The application of the cell block (CB) technique plays a vital role in cytological diagnosis, as blocks and slides can be further used for special stains, immunohistochemistry (IHC), and molecular pathological analysis. Several methods for making CBs have been reported, but their procedures and cellular yield are still deemed unsatisfactory. In this article, we used gellan gum (GG) as an adjuvant for CBs, which resulted in higher cellular yield with simpler procedures.

METHODS

CBs were prepared by using GG, copper sulfate, plasma/thrombin, or pregelatinized starch methods. The procedures of each of these four methods were then compared. CB sections were stained with hematoxylin and eosin (H&E), and the background and morphological features seen by H&E staining were compared. A preliminary IHC and fluorescence in situ hybridization (FISH) study was performed using cytology specimens from eleven and five cases, respectively. The expression of immunocomplex by IHC and the molecular signals detected by FISH were compared in CB sections made by the four methods and a section derived from the biopsy specimen block from the same patient. Feulgen staining, Alcian blue staining, and Masson trichrome staining were performed on the CB sections from 3 cases of pleural fluid. The cellular yield of CB sections from 83 cases according to the four methods was compared using NDP analysis software.

RESULTS

The results demonstrated that sections derived from CBs made with GG had a clear background and good morphological features by H&E staining. The expression of immunocomplex by IHC and the molecular signals of FISH detection in the sections from CBs made by GG were accurately located just as those in biopsy sections from the same patient. The DNA, acidic mucus, and fibrin could be clearly identified through special stains in the CB sections. The procedures involved in the GG method were easily controllable and the coagulated gel increased the ease by which the CB was embedded and sectioned. Specifically, sections from CBs made by the GG method contained higher cellular yield because cells could be concentrated on the bottom of the gel after centrifugation.

CONCLUSION

This novel method for making CBs is a practical, simple method that can result in higher cellular yield. This method is therefore worth promoting in clinical applications.

Lymphoproliferative disorder involving body fluid: diagnostic approaches and roles of ancillary studies

Lymphocyte-rich effusions represent benign reactive process or neoplastic condition. Involvement of lymphoproliferative disease in body cavity is not uncommon, and it often causes diagnostic challenge. In this review, we suggest a practical diagnostic approach toward lymphocyte-rich effusions, share representative cases, and discuss the utility of ancillary tests. Cytomorphologic features favoring neoplastic condition include high cellularity, cellular atypia/pleomorphism, monomorphic cell population, and frequent apoptosis, whereas lack of atypia, polymorphic cell population, and predominance of small T cells usually represent benign reactive process. Involvement of non-hematolymphoid malignant cells in body fluid should be ruled out first, followed by categorization of the samples into either small/medium-sized cell dominant or large-sized cell dominant fluid. Small/medium-sized cell dominant effusions require ancillary tests when either cellular atypia or history/clinical suspicion of lymphoproliferative disease is present. Large-sized cell dominant effusions usually suggest neoplastic condition, however, in the settings of initial presentation or low overall cellularity, ancillary studies are helpful for more clarification. Ancillary tests including immunocytochemistry, in situ hybridization, clonality test, and next-generation sequencing can be performed using cytologic preparations. Throughout the diagnostic process, proper review of clinical history, cytomorphologic examination, and application of adequate ancillary tests are key elements for successful diagnosis.

Novel 1,3,4-Oxadiazole Derivatives of Pyrrolo[3,4-d]Pyridazinone Exert Anti-Inflammatory Activity without Acute Gastrotoxicity in the Carrageenan-Induced Rat Paw Edema Test

Background and Purpose

Due to the risk of gastrointestinal damage and various tissue toxicity associated with non-steroidal anti-inflammatory drugs (NSAIDs) use, investigating new anti-inflammatory agents with efficacy comparable to that of NSAIDs but reduced toxicity is still a major challenge and a clinical need. Based on our previous study, new 1,3,4-oxadiazole derivatives of pyrrolo[3,4-d]pyridazinone, especially 6-butyl-3,5,7-trimethyl-1-[[4-[[4-(4-nitrophenyl)piperazin-1-yl]methyl]-5-thioxo-1,3,4-oxadiazol-2-yl]methoxy]pyrrolo[3,4-d]pyridazin-4-one and 6-butyl-1-[[4-[[4-(4-chlorophenyl)-4-hydroxy-1-piperidyl]methyl]-2-thioxo-1,3,4-oxadiazol-5-yl]methoxy]-3,5,7-trimethyl-pyrrolo[3,4-d]pyridazin-4-one (hereafter referred to as the compounds 10b and 13b, respectively) seem to be promising anti-inflammatory agents. This study aimed to elucidate the effects of these two new derivatives on the course of experimental rat inflammation, liver and kidney function, and gastric mucosa.

Methods

The anti-inflammatory effect of compounds 10b and 13b was evaluated using the carrageenan-induced paw edema test in rats. The increase in paw volume (paw edema), prostaglandin E₂ (PGE₂), tumor necrosis factor-α (TNF-α) and myeloperoxidase (MPO) levels, histological alterations, and inflammatory cell infiltration in paw tissue were determined. Serum alanine transaminase (ALT) and aspartate transaminase (AST) activities, serum urea and creatinine levels, as well as changes in gastric mucosa, were measured as indicators of hepatic, renal, and gastric toxicity.

Results

Pretreatment with both novel derivatives at 10 mg/kg and 20 mg/kg doses reduced paw edema, counteracted the increased PGE₂ and TNF-α levels, reduced the influx of inflammatory cells, and decreased histopathological alterations in paw tissue. Compound 13b at a dose of 20 mg/kg was more effective than indomethacin in reversing the increased TNF-α levels and reducing the influx of inflammatory cells. Only compound 13b at all studied doses (5, 10, or 20 mg/kg) counteracted the increased MPO level in paw tissue. Both compounds neither caused alterations in ALT, AST, urea, creatinine parameters nor gastric mucosal lesions.

Conclusion

New compounds exert an anti-inflammatory effect, presumably via inhibiting inflammatory mediators release and inflammatory cell infiltration. Moreover, both possess a more favorable benefit–risk profile than indomethacin, especially compound 13b.

Technical aspects of the use of cytopathological specimens for diagnosis and predictive testing in malignant epithelial neoplasms of the lung

Lung cancer is a leading cause of cancer mortality worldwide but recent years have seen a rapidly rising proportion of cases of advanced non-small cell carcinoma amenable to increasingly targeted therapy, initially based on the differential response to systemic treatment of tumours of squamous or glandular differentiation. In two-thirds of the cases, where patients present with advanced disease, both primary pathological diagnosis and biomarker testing is based on small biopsies and cytopathological specimens. The framework of this article is an overview of the technical aspect of each stage of the specimen pathway with emphasis on maximising potential for success when using small cytology samples. It brings together the current literature addressing pre-analytical and analytical aspects of specimen acquisition, performing rapid onsite evaluation, and undertaking diagnostic and predictive testing using immunocytochemistry and molecular platforms. The advantages and drawbacks of performing analysis on cell block and non-cell block specimen preparations is discussed.

Sodium Alginate versus Plasma Thrombin Cell Blocks in Diagnostic Cytopathology: A Comparative Analysis

BACKGROUND

Cell blocks (CBs) are an essential adjunct in cytopathology practice. The aim of this study was to compare 2 techniques of CB preparation - plasma thrombin (PT) method with sodium alginate (SA) method for overall cellularity, morphological preservation, obscuring artefacts, immunocytochemistry (ICC), suitability for molecular analysis, and cost of preparation.

DESIGN

A total of 80 fine-needle aspirates from various sites and serous effusion samples were included. Of these cases, by random selection, 40 each were prepared by PT method and SA methods, respectively. The haematoxylin-eosin-stained sections from the formalin-fixed, paraffin-embedded CBs from both methods were evaluated in a blinded fashion by 2 cytopathologists and scored for cellularity, artefacts, and morphological preservation and analysed by χ2 test with Yates correction. We evaluated 6 cases from each method by ICC for a range of membrane, cytoplasmic and nuclear marker expression. DNA was extracted from four cases to evaluate their utility for molecular analysis.

RESULTS

CB sections from PT and SA techniques showed comparable cellularity and excellent cytomorphological preservation. Blue gel-like artefacts were common in the SA technique but did not interfere with morphological evaluation. ICC staining results were also similar. DNA yield and utility for PCR were also comparable. The SA-CB cost half that of PT-CB (USD 0.4 vs. USD 1).

CONCLUSION

SA technique of CB preparation is an excellent low-cost alternative to PT method for CB preparation.

The Contributory Role of Cell Blocks in Salivary Gland Neoplasms Fine Needle Aspirations Classified by the Milan System for Reporting Salivary Gland Cytology

(1) Background: The Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) was introduced in 2018, bringing an organ-specific classification system for salivary gland cytopathology. The aim of present study is to evaluate the MSRSGC prospectively, based on a two-year experience in the tertiary care center pathology department, and evaluate the role of routine cell block (CB) preparation in salivary gland cytopathological diagnostics. (2) Methods: In our institution, the Department of Pathology, Fimlab Laboratories, Tampere, Finland, the MSRSGC has been implemented in salivary gland cytopathology since January 2018 and, over a two-year period (January 2018–December 2019), there were 365 fine-needle aspirations, of which 164 had a surgical follow-up. The CB methods used were Plasma-thrombin, the collection of visible fragments, and the Shandon and in-house methods. (3) Results: The MSRSGC diagnostic figures were as follows: accuracy 87.5%, sensitivity 45.8% and specificity 98.9%. For diagnostic categories of MSRSGC (non-neoplastic, benign neoplasm and malignant neoplasm) (n = 63) diagnostic accuracy was 98.4%, and for undetermined categories (atypia of undetermined significance, salivary gland neoplasm of uncertain malignant potential and suspicious for malignancy) (n = 49) diagnostic accuracy was 73.5%. Non-contributory cell blocks resulted more often in a false negative diagnosis (25%, 3/12) than a true negative diagnosis (10%, 7/73, p < 0.001), and is, most likely, an insufficient cytological diagnosis (86%, 18/21, p < 0.001). (4) Conclusion: The application of MSRSGC and CBs are beneficial in salivary gland cytological diagnosis, increasing diagnostic accuracy and, thus, patients’ management and treatment.

Performance of Rapid On-Site Evaluation in Breast Fine-Needle Aspiration Biopsies: Identifying Areas of Diagnostic Challenge

INTRODUCTION

Fine-needle aspiration (FNA) is a well-established method for sampling breast lesions with high accuracy and positive predictive value. Despite its decline in recent years relative to the use of core needle biopsies, there are several advantages to FNA which include cost-effectiveness, low complication rate, and the ability to perform rapid on-site evaluation (ROSE). The aim of this study was to evaluate breast FNAs with ROSE to identify diagnostic challenges during ROSE.

MATERIALS AND METHODS

We identified all breast FNAs with ROSE performed at Massachusetts General Hospital from January 2014 to December 2019. From the electronic medical record, clinical, radiological, and follow-up pathology results were recorded. Comparison between the rapid and final cytological diagnosis was made. All discrepancies were documented with major discrepancy defined as a malignant rapid interpretation not confirmed on final diagnosis or a negative rapid interpretation upgraded to suspicious or positive on final diagnosis.

RESULTS

The study cohort consisted of 483 breast FNAs with ROSE. The rapid and final cytological interpretations showed good correlation, with only 6 (1.2%) major discrepancies. Problematic areas included low-grade, lobular, and fibroepithelial lesions with low cellularity being a contributory factor to misclassification.

CONCLUSIONS

FNA remains a highly accurate method for the evaluation of breast lesions with ROSE.

An efficient and user-friendly method for cytohistological analysis of organoids

Organoid culture is a recently developed in vitro three-dimensional (3D) cell culture technology. It has wide applications in tissue engineering studies. However, histological analysis of organoid is quite complex and tedious for researchers. This study proposes a user-friendly, affordable and efficient method for making formalin-fixed paraffin embedded (FFPE) organoid blocks and Optimal Cutting Temperature compound (OCT) embedded frozen organoid blocks. This method implements a key pre-embedding step for preparing paraffin embedded organoid blocks, which could concentrate organoid together without damaging or loss of samples. This method could be used to process even a small number of organoids with high efficiency. In addition, with minor modifications, the method is readily applied for OCT embedded organoid blocks. The slides generated were ready for H&E staining, immunohistochemistry staining and immunofluorescent staining. The method described in this study can be easily used for routine histological analysis of organoid, and could be performed in general pathology labs and requires no dedicated equipment and reagent.

Cell Block and Its Impact in the Diagnosis of Jaw Lesions over Fine Needle Aspiration Cytology

OBJECTIVES

To determine the role and efficacy of fine needle aspiration cytology (FNAC) and cell block in diagnosis of jaw lesions and compare the agreement between FNAC and cell block to predict the diagnosis.

METHOD

The sample comprised 51 cases, including 12 odontogenic keratocysts (OKCs), 8 ameloblastomas, 22 radicular cysts, 7 dentigerous cysts, and 1 each of intraosseous mucoepidermoid carcinoma (MEC) and adenomatoid odontogenic tumor (AOT). FNAC samples remaining after hematoxylin and eosin (H&amp;E)-stained cytosmear diagnosis were centrifuged at 3,000 rpm for 10 min. The supernatant was discarded and sediment mixed with 2-3 mL alcohol and filtered. To this, 10% formalin was added, filtered, taken for routine processing, and stained with H&amp;E. The result of FNAC smear and cell block was compared with histopathological diagnosis.

RESULTS

On cytological examination of the smears, 7 OKCs and 22 radicular cysts were diagnosed, whereas ameloblastomas, AOT, intraosseous MEC, and dentigerous cysts were not. This gave an agreement of 56.8% with the biopsy reports. Cell block sections stained with H&amp;E of 12 OKCs, 22 radicular cysts, 1 MEC, and 3 cases of ameloblastoma offered a diagnosis in accordance with the biopsies giving an agreement of 74.5%, while dentigerous cyst and AOT failed to do so. In comparison with FNAC, additionally 5 cases of OKC and 1 of MEC could be detected, and in ameloblastoma, out of 8 cases, only 3 yielded a concordant diagnosis through the cell block technique.

CONCLUSION

In comparison with FNAC, the architectural pattern and the morphology of the cells were better preserved by the cell block technique. This substantiates that cell block could be used as an ancillary technique to aid in definitive diagnosis of head and neck swellings.

PD-L1 Testing in Cytological Non-Small Cell Lung Cancer Specimens: A Comparison with Biopsies and Review of the Literature

INTRODUCTION

Programmed death-ligand 1 (PD-L1) expression is used for treatment prediction in non-small cell lung cancer (NSCLC). While cytology may be the only available material in the routine clinical setting, testing in clinical trials has mainly been based on biopsies.

METHODS

We included 2 retrospective cohorts of paired, concurrently sampled, cytological specimens and biopsies. Also, the literature on PD-L1 in paired cytological/histological samples was reviewed. Focus was on the cutoff levels ≥1 and ≥50% positive tumor cells.

RESULTS

Using a 3-tier scale, PD-L1 was concordant in 40/47 (85%) and 66/97 (68%) of the paired NSCLC cases in the 2 cohorts, with kappa 0.77 and 0.49, respectively. In the former cohort, all discordant cases had lower score in cytology. In both cohorts, concordance was lower in samples from different sites (e.g., biopsy from primary tumor and cytology from pleural effusion). Based on 25 published studies including about 1,700 paired cytology/histology cases, the median (range) concordance was 81-85% (62-100%) at cutoff 1% for a positive PD-L1 staining and 89% (67-100%) at cutoff 50%.

CONCLUSIONS

The overall concordance of PD-L1 between cytology and biopsies is rather good but with significant variation between laboratories, which calls for local quality assurance.

Immunocytochemistry for diagnostic cytopathology-A practical guide

Cytological specimens, which are obtained by minimally invasive methods, are an excellent source of diagnostic material. Sometimes they are the only material available for diagnosis as well as for prognostic/predictive markers. When cytomorphology is not straightforward, ancillary tests may be required for a definitive diagnosis to guide clinical management. Immunocytochemistry (ICC) is the most common and practical ancillary tool used to reach a diagnosis when cytomorphology is equivocal, to differentiate entities with overlapping morphological features, and to determine the cell lineage and the site of origin of a metastatic neoplasm. Numerous immunomarkers are available, and some are expressed in multiple neoplasms. To rule out entities within a differential diagnosis, the use of more than one marker, sometimes panels, is necessary. ICC panels for diagnostic purposes should be customised based on the clinical context and cytomorphology, and the markers should be used judiciously to preserve material for additional tests for targeted therapies in the appropriate setting. This review offers a practical guide for the use of ICC for diagnostic cytopathology, covering the most commonly encountered non-hematolymphoid diagnostic scenarios in various body sites.

Cell Block Optimization: A Comparative Study of Quality Variables in 4 Different Cell Block Methods

OBJECTIVE

The cell block (CB) is an important adjunct to cytological preparations in diagnostic cytopathology. Optimizing cellular material in the CB is essential to the success of ancillary studies such as immunohistochemistry (IHC) and molecular studies (MS). Our aim was to identify which CB method was most suitable in a variety of specimen types and levels of cellularity.

STUDY DESIGN

We assessed 4 different CB methods, thrombin clot method (TCM), MD Anderson method (MDAM), gelatin foam method (GFM), and agar method (AM), with descriptive observations and ranking of the methods based on quantity of cells and morphological features.

RESULTS

TCM performed best in ranking for both quantity of cells and morphological features, followed by MDAM, GFM, and AM. Lack of adjuvant in the MDAM resulted in some unique morphological advantages which, however, also resulted in inconsistent performance. In low cellularity cases insufficient cells were frequently identified on slides from MDAM and AM CBs. Technique touch time was similar for all methods, with total processing time being shortest for TCM followed by MDAM, GFM, and AM.

CONCLUSIONS

TCM was the most robust CB technique, retaining high scores for ranking of quantity and morphology in a variety of specimen cellularities and specimen types.

The Role of Cell Blocks and Immunohistochemistry in Thyroid Atypia of Undetermined Significance/Follicular Lesion of Undetermined Significance Bethesda Category

INTRODUCTION

Thyroid cytology is a widely accepted tool in the clinical triaging of nodular lesions. Cell blocks (CBs) can help in the diagnosis of atypical lesions, namely, thyroid Bethesda category of Atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS).

METHODS

In a series of 224 AUS/FLUS thyroid samples with CB, we studied CB cellularity and feasibility of 3 immunohistochemical markers (cytokeratin 19 [CK19], HBME-1, and galectin-3) apart and in combination.

RESULTS

The CBs were non-diagnostic in 34 cases. Twenty-four CBs contained <10 cells, 45 CBs 10-50 cells, and 121 CBs >50 cells. Notably, more cellularity was found in CBs performed by plasma-thrombin and in-house techniques (p < 0.001). The diagnostic accuracy to detect malignancy was 65.1% for CK19, 72.1% for HBME-1, and 70.3% for galectin-3.

CONCLUSION

In conclusion, CB cellularity is essential for successful immunohistochemistry application and further diagnostic workup of AUS/FLUS cases.

Cytology samples and molecular biomarker testing in lung cancer-advantages and challenges

This review presents an overview on molecular diagnostic in lung cancer using cytologic samples. Every patient with advanced non-small cell lung cancer (NSCLC) should be tested for targetable driver mutations and gene arrangements. If a mutation is found, this may open an option for targeted therapy. As most of the NSCLC patients in advanced stage of disease are no candidates for surgery, these tests have to be performed on small biopsies or cytology samples. The most common and treatable gene alterations should be tested in every patient: EGFR, ALK, ROS1. A growing number of other genetic changes with targetable mutations may become treatable in the near future. To find patients who might profit from inclusion into clinical studies, relevant additional markers may be tested in an appropriate context. Another important approach for treatment is immunotherapy of lung cancer, which is guided by status of PD-L1 expression on tumour cells. The use of cytology samples carries considerable advantages: often, DNA of high quality is extracted thus enabling easy and precise analysis, and samples may be easily obtained. In case of effusions, effusion fluid seldom is not aspirated for immediate patient relief, so no additional dedicated procedure is needed. Some challenges exist: If the tumour cell count is low, mutations with a low allelic frequency may be missed. In cellblocks formalin-induced DNA, damage may obviate any DNA analysis. In very cellular smears, FISH may be impossible due to massive overlapping of nuclei. Autofluorescence may impede FISH analysis. Although there is no real universal test for genomic profiling for lung cancer, the pathology laboratory must be prepared to offer different assays on different specimens in order to address turnaround time and optimise detections of difficult tumour alterations such as gene fusions. The data from the literature demonstrate that cytology show consistent results, and it is a good alternative for lung cancer molecular testing.

Cell blocks in veterinary medicine: A comparison of two methods (cell tube and agar) in 52 effusions from dogs and cats

BACKGROUND

Cell blocks are alternative preparations of fluid cytological specimens. They can be used for immunochemical studies as complementary tools or when other techniques (eg, immunocytochemistry, flow cytometry) are not available.

OBJECTIVES

We aimed to provide comparative morphologic, immunohistochemical, and technical features of agar-based cell blocks (ACBs) and cell tube blocks (CTBs) from cavitary effusions.

METHODS

Agar-based cell blocks and CTBs were obtained from canine and feline effusions with neoplastic/atypical cells or with packed cell volumes ≥3%. Cellularity, RBC separation, and cellular features were evaluated on digitalized H&E slides with evaluators blinded to the method. The immunohistochemical intensity and nonspecific background were assessed on pan-cytokeratin and vimentin-stained slides. Overall yield was calculated, and morphologic and immunohistochemical features were compared among paired samples. Technical and cellular features were also described.

RESULTS

Agar-based cell blocks and CTBs yielded evaluable sections in 100% (52/52) and 98% (51/52) of the cases, respectively. Cellularity and RBC separation scores were significantly higher in CTBs. Similar staining intensities were observed, and background staining was more frequently seen in pan-cytokeratin-stained ACBs. Only basic materials and equipment were required for both methods. Agar-based cell block preparations were more operator dependent and difficult to standardize, whereas CTBs were easier to prepare, but laboratory processing was more demanding.

CONCLUSIONS

Both methods can be used to produce good sections for immunohistochemistry staining with no significant differences. Cell tube blocks are beneficial for RBC-rich samples, and little additional training is required to prepare the blocks. Both types of cell blocks are reliable, cost-effective methods that could be introduced in diagnostic laboratories to further characterize canine and feline effusions.

Impact of cytological pitfalls in the Bethesda System of Reporting Thyroid Cytopathology, on surgical decision-making of patients with thyroid nodules: Can these pitfalls be avoided?

INTRODUCTION

The purpose was to assess diagnostic accuracy of the Bethesda System of Reporting Thyroid Cytopathology, reasons for disagreement and cytological pitfalls with impact on surgical decisions in patients with thyroid nodules.

METHODS

Cases of thyroid cytology with histological follow up were included followed by cytological-histological correlation and were reviewed to look for reasons for discrepancies. The impact of disagreements and partial agreements on surgical decision was evaluated. Overall and complete diagnostic accuracy were calculated along with sensitivity, specificity, and positive and negative predictive values for malignant and neoplastic lesions.

RESULTS

Of 446 cases included in the study, there was complete agreement in 358 cases, partial agreement in 22 cases and disagreement in 66 patients. Overall diagnostic accuracy was 98.5% with sensitivity, specificity, positive predictive value and negative predictive value of 80%, 99.6%, 100%, 72.7% and 94.3% respectively for malignant lesions. Overall diagnostic accuracy was highest for the malignant category. Follicular patterned lesions, Hürthle cell-rich smears and overlapping cytological features between benign and malignant follicular neoplasm were the main reason of discrepancy. The discrepancy in cytological diagnosis altered the decision of type of surgery performed in 13.6% of the patients.

CONCLUSION

Fine needle aspiration cytology remains a powerful screening tool to aid decision-making in the majority of the patients. Histological-cytological discrepancy can adversely impact the management of patients. Factors causing an adverse impact on surgical management were rare and potential avoidable reasons for them were identified. Cytological pitfalls may be avoided through screening for minor components, clinico-radiological correlation and experience.

Determining the significance of psammoma bodies in pelvic washings: A 10-year retrospective review

BACKGROUND

Pelvic washing specimens are relatively common and are submitted for patients undergoing gynecologic surgery to evaluate them for metastatic or occult disease. Psammoma bodies are a relatively uncommon finding in these specimens. To date, large-scale studies of their cytologic-histologic correlates and thus clinical significance have been limited.

METHODS

A 10-year retrospective search for all pelvic washing specimens was performed, and all cases were reviewed for the presence of psammoma bodies. The findings for the corresponding surgical pathology specimens were then catalogued.

RESULTS

Psammoma bodies were present in 138 cases (3.6% of 3840 total pelvic washings). More than half of the cases (n = 73 [53%]) were associated with benign processes, including mesothelial hyperplasia (n = 44), endosalpingiosis (n = 11), endometriosis (n = 11), and ovarian cystadenoma/cystadenofibroma (n = 7). Nineteen cases (14%) were associated with serous borderline tumors. Malignancies were noted in a third of the cases (n = 46 [33%]) and were most frequently low-grade serous adenocarcinomas (n = 15), high-grade serous adenocarcinomas (n = 11), or endometrioid endometrial carcinomas (n = 8). Patients found to have benign processes (median age, 50 years) or borderline disease (median age, 56 years) were significantly younger than patients with malignancies (median age, 65 years; P < .0001). In addition, the correlation of cytologic interpretation categories with concurrent histopathologic findings showed that cytologic analysis was highly sensitive and specific in determining the nature of underlying processes.

CONCLUSIONS

The majority of psammoma bodies noted in pelvic washings were associated with benign processes or borderline tumors, with approximately a third of the cases associated with malignancies. Psammoma bodies in pelvic washings from younger patients were significantly more likely to be associated with benign processes or borderline tumors.

Improved diagnostic yield of endoscopic ultrasound-fine needle biopsy with histology specimen processing

BACKGROUND

Endoscopic ultrasound-guided fine needle biopsy (EUS-FNB) has emerged as a safe, efficacious alternative to fine needle aspiration (FNA) for tissue acquisition. EUS-FNB is reported to have higher diagnostic yield while preserving specimen tissue architecture. However, data on the optimal method of EUS-FNB specimen processing is limited.

AIM

To evaluate EUS-FNB with specimen processing as histology vs EUS-FNA cytology with regards to diagnostic yield and specimen adequacy.

METHODS

All EUS-FNA and EUS-FNB performed at our institution from July 1, 2016, to January 31, 2018, were retrospectively analyzed. We collected data on demographics, EUS findings, pathology, clinical outcomes, and procedural complications in two periods, July 2016 through March 2017, and April 2017 through January 2018, with predominant use of FNB in the second data collection time period. FNA specimens were processed as cytology with cell block technique and reviewed by a cytopathologist; FNB specimens were fixed in formalin, processed for histopathologic analysis and immunohistochemical staining, and reviewed by an anatomic pathologist. Final diagnosis was based on surgical pathology when available, repeat biopsy or imaging, and length of clinical follow up.

RESULTS

One hundred six EUS-FNA and EUS-FNB procedures were performed. FNA alone was performed in 17 patients; in 56 patients, FNB alone was done; and in 33 patients, both FNA and FNB were performed. For all indications, diagnostic yield was 47.1% (8/17) in FNA alone cases, 85.7% (48/56) in FNB alone cases, and 84.8% (28/33) in cases where both FNA and FNB were performed (P = 0.0039). Specimens were adequate for pathologic evaluation in 52.9% (9/17) of FNA alone cases, in 89.3% (50/56) of FNB alone cases, and 84.8% (28/33) in cases where FNA with FNB were performed (P = 0.0049). Tissue could not be aspirated for cytology in 10.0% (5/50) of cases where FNA was done, while in 3.4% (3/89) of FNB cases, tissue could not be obtained for histology. In patients who underwent FNA with FNB, there was a statistically significant difference in both specimen adequacy (P = 0.0455) and diagnostic yield (P = 0.0455) between the FNA and FNB specimens (processed correspondingly as cytology or histology).

CONCLUSION

EUS-FNB has a higher diagnostic yield and specimen adequacy than EUS-FNA. In our experience, specimen processing as histology may have contributed to the overall increased diagnostic yield of EUS-FNB.

Immunocytochemistry practices in European cytopathology laboratories-Review of European Federation of Cytology Societies (EFCS) online survey results with best practice recommendations

BACKGROUND

Variability in preanalytical and analytical steps for immunocytochemistry (ICC) on cytology samples is poorly defined. The objective of this study was to evaluate current practices for ICC on cytology samples in European laboratories.

METHODS

A link to an online survey with 19 questions about ICC practices was distributed to cytology laboratories through national representatives in the European Federation of Cytology Societies.

RESULTS

In total, 245 laboratories responded to the survey by January 30, 2019. Cell blocks, cytospins, liquid-based cytology (LBC) preparations, and smears alone or in combination with other preparations were used for ICC in 38%, 22%, 21%, and 19% of laboratories, respectively. In general, various combinations of preparations were used for ICC in greater than one-half of laboratories (147 of 245; 60%), whereas only 1 specific type of cytology preparation was used in the remaining 98 of 245 laboratories (40%) laboratories. The majority of laboratories (217 of 226; 96%) performed ICC on automated platforms using protocols that were the same as those used for formalin-fixed, paraffin-embedded samples (238 of 527 laboratories; 45%), either optimized (138 of 527 laboratories; 26%) or optimized and validated (151 of 527 laboratories; 29%) for cytology preparations. Positive control slides, negative control slides, and external quality control were used in 174 of 223 (78%), 112 of 223 (50%), and 111 of 120 (50%) laboratories, respectively. Greater than 1000 ICC tests were performed yearly in 34% of laboratories (65 of 191; average, 1477 tests; median, 500 tests).

CONCLUSIONS

ICC is extensively performed in European laboratories using variously prepared cytology preparations on automated platforms, mostly without quality-assurance measures.

Influence of preanalytical variables on performance of delta-like protein 3 (DLL3) predictive immunohistochemistry

DLL3 might become a predictive immunohistochemical marker in small cell carcinoma of the lung (SCLC). We investigated the influence of pre-analytical handling of samples on the performance of DLL3 immunohistochemistry (IHC) using DLL3 SP347 ready to use assay (Ventana). DLL3 positive cell lines were subjected to different experimental conditions mimicking the pre-analytical variation in daily clinical practice. Formalin fixation of 24 h led to the most optimal results of DLL3 IHC. Longstanding fixation in Cytolyt, methanol-based fixative for cytology samples, but also decalcification using a mix of formic- and hydrochloracid resulted in decreased DLL3 staining. Postponed staining of blanc slides for 3 months also decreased DLL3 IHC. Postponed fixation of the SCLC cell lines did not influence the performance of DLL3 IHC, although this might be different in the tissues than in the cell lines. In conclusion, different pre-analytical variables decrease the performance of DLL3 IHC. These findings are essential for implementing novel predictive immunohistochemical biomarkers in daily pathology practice.

Processing and Reporting of Cytology Specimens from Mediastinal Lymph Nodes Collected using Endobronchial Ultrasound-Guided Transbronchial Needle Aspiration: A State-of-the-Art Review

Endobronchial ultrasound (EBUS)-guided transbronchial needle aspiration (TBNA) is presently the preferred modality for sampling mediastinal lymph nodes. There is an unmet need for standardization of processing and reporting of cytology specimens obtained by EBUS-TBNA. The manuscript is a state-of-the-art review on the technical aspects of processing and reporting of EBUS-TBNA specimens. A literature search was conducted using the PubMed database, and the available evidence was discussed among the authors. The evidence suggests that at least one air-dried and one alcohol-fixed slide should be prepared from each lymph node pass. The remaining material should be utilized for microbiological analysis (in saline) and cell block preparation (10% formalin or other solutions). Wherever available, rapid-onsite evaluation should be performed to assess the adequacy of the sample and guide the need for additional material. The lymph node aspirate should also be collected in Roswell Park Memorial Institute solution in cases where lymphoma is under consideration. The use of liquid-based cytology provides good quality specimens that are free from blood and air-drying artifacts and can be used wherever available. Sample adequacy and the diagnostic category should be furnished separately in the cytology report.

Tumor Cell Representation by an Improvised Technique of Fine-Needle Aspiration Specimen Acquisition and Cell Block Preparation: Our Experience in Lung Cancer Cases in a Peripheral Center of Eastern India

Background

Being a minimally invasive diagnostic technique, Fine-Needle Aspiration Cytology (FNAC) has become the first-line test and corresponding aspirated material has become the target specimen for diagnosis and ancillary tests in lung carcinoma. Although the role of Cell Blocks (CBs) in diagnosis and in ancillary testing is well recognized in literature, limited attention has been paid to specimen procurement and triage in the preparation of CBs. In the present scenario, CBs are not consistently optimal because of its low cellularity.

Aims

This study is aimed to describe an improvised technique of specimen acquisition and cell block preparation in CT-guided FNACs of lung carcinoma cases in a resource-constrained center and to assess its efficacy for optimal representation of cellularity, morphology, and architecture.

Materials and Methods

Total 85 lung carcinoma cases undergoing CT-guided FNAC in our center from February 2017 to January 2018 were included in this study. 4 to 5 direct smears and subsequent CBs were made from material obtained by single pass. Cellularity of smears and corresponding cell blocks were assessed and categorized according to a scoring system (score 1 to 3 for number of cells <50, 50-100, >100, respectively). Preserved architecture and morphology were also assessed in smears and CBs.

Results

The evaluated samples showed a cellularity score 3 in 65.4%CBs and score 2 in 24.7% CBs. Overall, 90.1% cell blocks had acceptable cellularity. Cell morphology was preserved in all CBs of acceptable cellularity, except for two adenocarcinoma, one squamous cell carcinoma, and one small cell carcinoma blocks. Cellular architecture was also preserved in all CBs of acceptable cellularity.

Conclusions

This simple improvised technique of CB preparation optimized its cellularity, morphology, and architectural preservation, even after adequate cellular FNA smears.

Cell Block as a Surrogate for Programmed Death-Ligand 1 Staining Testing in Patients of Non-Small Cell Lung Cancer

Introduction: Programmed death-ligand 1 (PD-L1) staining is used in clinical practice to guide the proper use of immune checkpoint inhibitors. This study aimed to investigate the accuracy of PD-L1 staining of non-small cell lung cancer (NSCLC) cytological cell block samples.

Methods: Paired cytological cell block and surgical resection samples were consecutively collected from January 2016 to February 2017 in Shanghai Pulmonary Hospital, Tongji University. Two trial-validated PD-L1 assays (28-8 and SP142) were used to quantify PD-L1 expression.

Results: A total of 112 pairs of specimens were collected, including 68(60.7%) adenocarcinomas and 28(25.0%) squamous cell carcinomas. Based on a tumor proportion score (TPS) cutoff of 1% for the 28-8 and SP142 assays, PD-L1 expression was positive in 78.6% and 58.9% of surgical samples respectively, while PD-L1 expression was positive in 67.9% and 25.0% of cytological cell block samples.

Based on staining by each antibody, fair to substantial concordance of PD-L1 expression was observed for cytological cell block specimens as compared to surgical resection (𝛋 ranges from 0.377 to 0.686). However, as the tumor cells in the cell block specimen increased, the consistency of PD-L1 expression increased. The concordance of PD-L1 expression in cell blocks with abundant cellularity was nearly perfect with various cutoffs (28-8: tumor cells over 400; SP142: tumor cells over 500).

Conclusion: Cytological cell block specimens may serve as a surrogate for PD-L1 staining in patients of NSCLC when more than 400-500 cancer cells were contained (over 400 cancer cells for 28-8, over 500 cancer cells for SP142).

Indian Academy of Cytologists Guidelines for Collection, Preparation, Interpretation, and Reporting of Serous Effusion Fluid Samples

Cytological examination plays an important role in the initial work-up of the serous cavity effusion fluids to find out the possible etiology as benign or malignant. Among malignant effusions, cytology is helpful in determining the exact type, site, and stage of the tumor. However, for reporting effusion cytology specimens, there is no consistent and reproducible reporting system.

Plasma-thrombin cell blocks: Potential source of DNA contamination

BACKGROUND

Cell blocks are being used more frequently in cytology for ancillary testing, including molecular diagnostics. There are several different methods of processing cell blocks, with plasma-thrombin being one of the most common. Plasma is a blood-derived product and may be a source of DNA. The aim of this study was to determine whether the plasma used for the plasma-thrombin cell block method has amplifiable DNA that may potentially interfere with molecular testing results.

METHODS

Expired bags of fresh frozen plasma were collected from a blood bank. From each sample, DNA was extracted from a 1-mL aliquot with the QIAsymphony MIDI kit (Qiagen). The concentration of DNA was measured on a NanoDrop instrument. The amplifiable DNA quality was assessed by polymerase chain reaction (PCR) with primers to generate amplicons of various sizes. Characterization was performed with the AmpFLSTR Identifiler Plus PCR kit with capillary electrophoresis.

RESULTS

Twenty samples from 20 bags were collected. All samples showed amplifiable DNA despite low DNA concentrations in a few cases. PCR amplification revealed the presence of high-quality amplifiable DNA (up to 600 base pairs). DNA was amplified at the 16 loci interrogated in all samples tested with the AmpFLSTR Identifiler Plus PCR kit.

CONCLUSIONS

The presence of genomic DNA in plasma may theoretically interfere with results of molecular testing. Particularly in clinical samples with low cellularity, the DNA in plasma may potentially either mask the presence of minute amounts of tumor-derived DNA or lead to a false-positive result.

New Cell Block Method to Enhance the Cellular Yield in Mucous and/or Bloody Samples

OBJECTIVE

Cell blocks (CBs) are used to complement cytological diagnosis and for ancillary testing. Dissatisfaction with the cellular yield of the CB is widely recognized. Various techniques have been developed to increase the diagnostic utility of CBs.

STUDY DESIGN

We invented a new CB technique to increase cellular yield and diagnostic accuracy suitable especially for mucous and/or bloody cytological samples.

RESULTS

The new CB technique is described in detail with illustrations and cases, where it increased the cellular yield and diagnostic accuracy. CBs prepared by this method are suitable also for ancillary techniques, namely immunocytochemistry.

CONCLUSIONS

The newly described method showed a better cellular yield in mucous and/or bloody cytological specimens.

Cell-blocks are suitable material for programmed cell death ligand-1 immunohistochemistry: Comparison of cell-blocks and matched surgical resection specimens in lung cancer

Objective

Programmed cell death ligand‐1 (PD‐L1) has emerged as a predictive biomarker in lung cancer. PD‐L1 immunohistochemistry (IHC) assay predicts the response to immunotherapy, but cytology specimens are often the only samples available in a considerable proportion of advanced lung cancer patients. We delineate practical feasibility and efficacy of cytology cell‐block (CB) specimens for PD‐L1 expression and concordance between cytology CBs and surgical resection specimens.

Methods

In total, 58 eligible patients with primary lung cancer who received computed tomography‐guided percutaneous needle aspiration and surgery were included. PD‐L1 IHC (clone SP263) was performed on CBs prepared from residual liquid‐based cytology material and matched surgical resection specimens. PD‐L1 positive tumour cell proportion was categorised in four score groups: (a) <1%; (b) ≤1% to <10%; (c) ≤10% to <50%, (d) ≥50%.

Results

Comparison of PD‐L1 expression in cytology CBs and matched surgical resection specimens showed a high concordance (κ value 0.65). According to the therapeutic guideline of immunotherapeutic agents, a positive percent agreement was 94.34%, and a negative percent agreement was 100% at a cut‐off value for positivity of 1% PD‐L1 expression. There was a significant difference observed with regard to rates of PD‐L1 positivity when comparing smoking history (P = 0.02), age (P = 0.04) and pathological TNM stage (P = 0.04).

Conclusions

The results show that cytology CBs evaluated for PD‐L1 IHC assay have high concordance with matched surgical resection specimens and can be used for assessing PD‐L1 expression. Also, we propose that CBs are suitable materials for evaluating PD‐L1 expression while simultaneously performing both diagnostic and molecular tests.

This study showed that cytology cell‐blocks (CBs) evaluated for PD‐L1 immunohistochemistry (IHC) assay have high concordance with matched surgical resection specimens and can be used for assessing PD‐L1 expression. Also, we propose that CBs are suitable materials for evaluating PD‐L1 expression while simultaneously performing both diagnostic and molecular tests.

CellBlockistry: Chemistry and art of cell-block making - A detailed review of various historical options with recent advances

Cell-blocks are paraffin-embedded versions of cytology specimens comparable to the formalin-fixed paraffin-embedded (FFPE) tissue from surgical pathology specimens. They allow various elective ancillary studies on a variety of specimens with enhanced cytopathologic interpretation, including opportunity to perform molecular tests. However, different dictionaries and internet search engines primarily project "cellblock" and "cell block" definition in relation to prisons. Most of the top searches lead to information related to "prison cells" followed by a few cytopathology-related searches. Due to this in the current review, it is recommended that the word for cytopathology purposes should be hyphenated and spelled as "cell-block." Cell-blocks have been increasingly indicated on most cytology specimens. Its role is growing further with the ongoing addition of new immunohistochemistry (IHC) markers with technical advances including multicolor IHC and the SCIP (subtractive coordinate immunoreactivity pattern) approach. In addition, it is an important source of tissue for many ancillary studies even as archived material retrospectively at later stage of management if the cell-blocks are improved qualitatively and quantitatively. Because of this, the significance of cell-block is critical with the increasing number of molecular markers standardized predominantly on FFPE tissue. As compared to core biopsies, high-quality cell-blocks prepared with enhanced methodologies predominantly contain concentrated diagnostic tumor cells required for the molecular tests without significant stromal contamination. This review introduces the terminology of CellBlockistry as the science of studying chemistry and the art of achieving quantitatively and qualitatively improved cell-blocks from different types of specimens. The review addresses the cell-block making process as "cell-blocking" and discusses different historical limitations with emphasis on recent advances.

Use of the term atypical cells in the reporting of ascitic fluid cytology: A caveat

Background

Abdominal paracentesis is a routine diagnostic procedure for assessment of patients with recent onset or worsening of ascites.

Objectives

The objective of the study is to (1) review clinically confirmed cases of malignancy with negative, atypical, and suspicious cytology reports and provide reasoning for discrepancies and (2) recalculate sensitivity, specificity, and predictive values after review.

Materials and Methods

Papanicolaou smears of ascitic fluid paracentesis samples received over one calendar year were reviewed retrospectively by an expert in cytopathology blinded to the final clinical and/or histopathological diagnoses. Cases with discrepancies after review were noted. Sensitivity, specificity, and predictive values were calculated before and after review of slides. Data were analyzed using SPSS version 16.

Results

Malignant etiology was identified in 49/115 cases (42.6%) with female genital tract being the most common site of malignancy (22, 44.8%). The remaining 66 (57.4%) had a benign etiology with hepatic cirrhosis in 42 cases (63.6%). A review revealed discrepancies in five cases, three of which were earlier called negative for malignant cells (one case each of ovarian adenocarcinoma, cecal adenocarcinoma, and cholangiocarcinoma). Two cases of ovarian adenocarcinoma that were reported as atypical/reactive mesothelial hyperplasia showed malignant cells upon review. Sensitivity and specificity after review were 69.4% and 100%, respectively, with 100% positive predictive value.

Conclusion

Being a minimally invasive procedure, abdominal paracentesis continues to be an important diagnostic tool in guiding patient management. A proper morphological assessment with adequate clinical information and correlation with other investigations can be used to arrive at a definitive diagnosis in most cases. The term "atypical" can be misleading and is often used for want of clinical information and is best avoided.

Immunocytochemistry for predictive biomarker testing in lung cancer cytology

With an escalating number of predictive biomarkers emerging in non-small cell lung carcinoma (NSCLC), immunohistochemistry (IHC) is being used as a rapid and cost-effective tool for the screening and detection of many of these markers. In particular, robust IHC assays performed on formalin-fixed, paraffin-embedded (FFPE) tumor tissue are widely used as surrogate markers for ALK and ROS1 rearrangements and for detecting programmed death ligand 1 (PD-L1) expression in patients with advanced NSCLC; in addition, they have become essential for treatment decisions. Cytology samples represent the only source of tumor in a significant proportion of patients with inoperable NSCLC, and there is increasing demand for predictive biomarker testing on them. However, the wide variation in the types of cytology samples and their preparatory methods, the use of alcohol-based fixatives that interfere with immunochemistry results, the difficulty in procurement of cytology-specific controls, and the uncertainty regarding test validity have resulted in underutilization of cytology material for predictive immunocytochemistry (ICC), and most cytopathologists limit such testing to FFPE cell blocks (CBs). The purpose of this review is to: 1) analyze various preanalytical, analytical, and postanalytical factors influencing ICC results; 2) discuss measures for validation of ICC protocols; and 3) summarize published data on predictive ICC for ALK, ROS1, EGFR gene alterations and PD-L1 expression on lung cancer cytology. Based on our experience and from a review of the literature, we conclude that cytology specimens are in principal suitable for predictive ICC, but proper optimization and rigorous quality control for high-quality staining are essential, particularly for non-CB preparations.

Role of Ancillary Techniques in Fluid Cytology

The cytologic evaluation of serous effusions may be challenging for a number of reasons. Distinction of benign, reactive conditions from malignancy represents the main focus when examining these specimens. The morphologic diagnosis of malignancy may be difficult due to the relative paucity of abnormal cells. In other situations, cellularity is not an issue, but the ability to confidently identify a second, foreign (i.e., tumor) population within a background mesothelial cells on the basis of cytomorphologic features alone may pose problems. Cases with definitive morphologic evidence of malignancy may require additional studies in order to determine the tumor subtype and, in the case of carcinoma, the primary site of origin. Cases in which a definitive and precise diagnosis of malignancy is made may be optimal candidates for further molecular testing in order to gain prognostic information and guide personal therapeutic decisions. Finally, while an inflammatory or infectious condition can be suggested on the basis of cellular components and associated background elements, the identification of causative agent(s) may be difficult without additional studies. In all of these situations, the use of ancillary studies and techniques is critical; their utility and appropriate application are the subject of this review.

Lung Molecular Cytopathology: EGFR and Beyond

Lung cancer (LC) is the leading cause of cancer-related mortality. Unfortunately, most patients of LC present at the advanced stage of the disease with a poor prognosis and 1-year survival of less than 20%. At the advanced stage of the disease, surgical resection cannot be possible, hence small biopsy or cytology specimens remain a choice for their correct diagnosis. The recognition of molecular drivers has revolutionized the treatment paradigm of non-small cell lung cancer (NSCLC) with introduction of tyrosine kinase inhibitors. Epidermal growth factor receptor (EGFR) gene mutations were identified, first, to be targeted in NSCLC followed by activating fusions in anaplastic lymphoma kinase (ALK) and rearrangements in c-ros oncogene 1 (ROS1) genes. In addition, the encouraging progress of immunotherapy in patients with NSCLC has been associated with predictive biomarker testing in the form of programmed death ligand-1 (PD-L1) immunohistochemistry assay. To test for these alterations, accurate biomarker testing is needed from biopsy or cytology specimens. In this brief review, testing of biomarkers is discussed using cytology specimens.

Validation of immunohistochemical tests performed on cytology cell block material: Practical application of the College of American Pathologists' guidelines

The advent of fiberoptic endoscopy with biopsy has revolutionized procurement of specimens from deep sites. This has translated into more cytologic specimens whereby the material is limited and best handled by cytology laboratory staff. While the diagnosis of the pathologic process is of utmost importance, there is increasing expectation that the diagnosis be specific and accurate as not to require additional biopsy for initiation of treatment. This expectation has driven demand in immunohistochemical (IHC) and molecular studies conducted specifically on material processed as cytology specimens. The Clinical Laboratory Improvement Amendments of 1988 requires laboratories in the United States of America to verify the performance of patient tests. Due to varying laboratory practices with respect to validation of IHC assays, the College of American Pathologists introduced guidelines for analytic validation of IHC tests. These guidelines address how to perform validation by recommending the number of cases in the validation set, comparator concordance, and when to revalidate. The main thrust of the guidelines is based on formalin-fixed paraffin-embedded tissue with only one expert consensus opinion referring to validation of IHC tests on cytology specimens which delegates to the medical director, the determination of number of positive and negative cases to be tested. This article will outline how an academic center approaches validation of IHC studies performed on cytology cell block specimens using the College of American Pathologists guidelines. A stepwise approach from selection of antibodies to validate followed by building the validation panel and evaluating the stain results for concordance against the gold standard of histology tissue specimen will be described. A rationale for dealing with discordant results and future innovations will conclude the report.

Conventional transbronchial needle aspiration is promising for identifying EGFR mutations in lung adenocarcinoma

Background

Conventional transbronchial needle aspiration (TBNA) is advantageous for the one‐step diagnosis and staging of lung adenocarcinoma under topical anesthesia and conscious sedation. We examined its efficacy for identifying EGFR mutations.

Methods

Forty‐seven patients with proven or suspected lung adenocarcinoma indicated for hilar‐mediastinal lymph node (LN) staging between June 2011 and December 2017 were enrolled. The cellblock was prepared using the plasma‐thrombin method. TaqMan PCR was used to detect mutations. Considering cost effectiveness, only the sample with the highest tumor cell fraction in the same patient was chosen for analysis.

Results

TBNA provided positive results of malignancy in 27 patients. Seventeen patients (63.0%) had cellblocks eligible for mutation testing. Bronchial biopsy (n = 6), neck LN fine needle aspiration (n = 1), and brushing (n = 1), provided higher tumor cell fractions for analysis in eight patients. TBNA was the exclusive method used in nine patients (19.1%). For patients with an inadequate TBNA cellblock, bronchial biopsy (n = 5), neck LN fine needle aspiration (n = 3), computed tomography‐guided transthoracic needle biopsy (n = 1), and brushing (n = 1) were used for analysis. Modification to specimen processing to prevent exhaustion by cytology after June 2016 improved the adequacy of cellblock samples (9/10, 90% vs. 8/17, 47.1%; P = 0.042).

Conclusions

These findings suggest the promising role of conventional TBNA and highlight the challenges of doing more with less in an era of precision medicine.

A practical cytological approach to the diagnosis of breast-implant associated anaplastic large cell lymphoma

The role of cytopathology in malignant lymphoma is largely restricted to primary screening in patients with lymphadenopathy of unknown causes and evaluation of relapse and transformation during follow-up of patients with known and fully classified malignant lymphoma. Few lymphoma diagnoses fully rely on cytology, although breast-implant associated anaplastic large cell lymphoma is currently the centre of clinical attention. Due to the major attention both in the medical and lay media for the recently substantiated high lymphoma risk in women with breast implants, cytopathology departments now frequently receive seroma fluid aspirates with this specific differential diagnostic consideration. In this review, we discuss clinico-pathological aspects of breast-implant associated anaplastic large cell lymphoma from a cytological point of view and provide guidelines for the processing of aspirates in daily practice and strategies for diagnostic work-up of seroma fluids.

Best Practices Recommendations for Diagnostic Immunohistochemistry in Lung Cancer

Since the 2015 WHO classification was introduced into clinical practice, immunohistochemistry (IHC) has figured prominently in lung cancer diagnosis. In addition to distinction of small cell versus non-small cell carcinoma, patients' treatment of choice is directly linked to histologic subtypes of non-small cell carcinoma, which pertains to IHC results, particularly for poorly differentiated tumors. The use of IHC has improved diagnostic accuracy in the classification of lung carcinoma, but the interpretation of IHC results remains challenging in some instances. Also, pathologists must be aware of many interpretation pitfalls, and the use of IHC should be efficient to spare the tissue for molecular testing. The International Association for the Study of Lung Cancer Pathology Committee received questions on practical application and interpretation of IHC in lung cancer diagnosis. After discussions in several International Association for the Study of Lung Cancer Pathology Committee meetings, the issues and caveats were summarized in terms of 11 key questions covering common and important diagnostic situations in a daily clinical practice with some relevant challenging queries. The questions cover topics such as the best IHC markers for distinguishing NSCLC subtypes, differences in thyroid transcription factor 1 clones, and the utility of IHC in diagnosing uncommon subtypes of lung cancer and distinguishing primary from metastatic tumors. This article provides answers and explanations for the key questions about the use of IHC in diagnosis of lung carcinoma, representing viewpoints of experts in thoracic pathology that should assist the community in the appropriate use of IHC in diagnostic pathology.

Predictive potential and need for standardization of PD-L1 immunohistochemistry

Checkpoint inhibitors targeting the PD-1/PD-L1 axis are a promising treatment option in several tumor types. PD-L1 expression detected by immunohistochemistry is the first clinically validated predictive biomarker for response to PD-1/PD-L1 inhibitors, though its predictive value varies significantly between tumor types. With the approval of pembrolizumab monotherapy for treatment-naïve, advanced non-small cell lung cancer, PD-L1 testing has to become broadly available in pathology laboratories. When PD-L1 testing started to be introduced in routine pathology practice, there were several open issues, which needed to be addressed in order to provide accurate results. This review will discuss the complex biological background of PD-L1 as predictive biomarker, summarize relevant clinical trials in NSCLC illustrating the origin of different PD-L1 expression cutoffs and scorings, and address issues important for PD-L1 testing including the analytical comparability of the different clinical trial-validated PD-L1 immunohistochemistry assays, the potential of laboratory-developed tests, and an overview of the different scoring algorithms.

Tru-cut/core Biopsy versus FNAC: Pulmonary Tumors

Primary lung epithelial malignancies are the most common neoplasms among all pulmonary tumors. Lung cancer (LC) is the leading cause of cancer-related mortality for which a histologic or cytologic confirmation of malignancy is required before treatment. Specimen management is an important task for pathologists in the field of LC. Biopsy and fine needle aspiration are comparable. It is desirable to have both for diagnosis and mutation testing to maximize their use for patient care.

Cell Block in Cytological Diagnostics: Review of Preparatory Techniques

OBJECTIVE

The cell block (CB) technique refers to the processing of sediments, blood clots, or grossly visible tissue fragments from cytological specimens into paraffin blocks that can be cut and stained by the same methods used for histopathology. The technique brings additional tissue architectural information. CB can be used for ancillary techniques such as immunocytochemistry and molecular techniques.

STUDY DESIGN

We reviewed the literature on the various preparatory techniques of CBs.

RESULTS

There is a wide range of preparatory techniques for CBs and no golden standard for CBs exists: tens of methods are used in various institutions. The majority of the methods are modified in house techniques with a few commercially available kits. The techniques most commonly used are the plasma/thrombin method, the agar method, and commercially available Histogel- and Cellient CB-methods. Dissatisfaction with the cellular yield of the CBs is common.

CONCLUSIONS

In the CBs, the cytological material is preserved for future use, which is a tremendous advantage in the era of targeted therapy and biobanking. The CB is thus central to the future of cytology: more can be done with less material and with less invasiveness to the patient.

Suitability of the CellientTM cell block method for diagnosing soft tissue and bone tumors

BACKGROUND

The diagnosis of tumors of soft tissue and bone (STB) heavily relies on histological biopsies, whereas cytology is not widely used. Cellient^TM cell blocks often contain small tissue fragments. In addition to Hematoxylin and Eosin (H&E) interpretation of histological features, immunohistochemistry (IHC) can be applied after optimization of protocols. The objective of this retrospective study was to see whether this cytological technique allowed us to make a precise diagnosis of STB tumors.

METHODS

Our study cohort consisted of 20 consecutive STB tumors, 9 fine-needle aspiration (FNAC) samples, and 11 endoscopic ultrasonography (EUS) FNACs and included 8 primary tumors and 12 recurrences or metastases of known STB tumors.

RESULTS

In all 20 cases, H&E stained sections revealed that diagnostically relevant histological and cytological features could be examined properly. In the group of 8 primary tumors, IHC performed on Cellient^TM material provided clinically important information in all cases. For instance, gastrointestinal stromal tumor (GIST) was positive for CD117 and DOG-1 and a PEComa showed positive IHC for actin, desmin, and HMB-45. In the group of 12 secondary tumors, SATB2 was visualized in metastatic osteosarcoma, whereas expression of S-100 was present in 2 secondary chondrosarcomas. Metastatic chordoma could be confirmed by brachyury expression. Two metastatic alveolar rhabdomyosarcomas were myf4 positive, a metastasis of a gynecologic leiomyosarcoma was positive for actin and estrogen receptor (ER) and a recurrent dermatofibrosarcoma protuberans expressed CD34.

CONCLUSION

In the proper clinical context, including clinical presentation with imaging studies, the Cellient^TM cell block technique has great potential for the diagnosis of STB tumors.

HER2 Overexpression in Retinoblastoma: A Potential Therapeutic Target?

Background

Retinoblastoma (RB) is the most common primary intraocular malignancy. Current therapies are associated with high morbidity in the short- and long-term. Human epidermal growth factor receptor 2 (HER2) is a transmembrane protein detected in 15-30% of breast cancers, but it has also been described in other malignancies. Recently, it has been claimed that a truncated version of this protein is expressed in RB, responsive to directed therapies in vitro. We scored HER2 overexpression in RB tissue samples and discussed its potential clinical utility.

Methods

HER2 overexpression was investigated using immunohistochemistry; the overexpression was evaluated with a score ranging from 0 to 3+ according to the membranous staining pattern in archival formalin-fixed, paraffin-embedded RBs.

Results

A total of 60 RB cases and a RB cell line (Y79) were considered. The mean age at enucleation was 31.6 ± 31.5 months. The mean time from diagnosis to enucleation was 11.8 ± 11.2 months (range 1-44). Five (8%) cases were multifocal. HER2 overexpression was negative in all RB cases (49 cases scored 0 and 11 scored 1+) and in the Y79 cell line.

Conclusions

Overall, we were not able to demonstrate the overexpression of HER2. Further studies should clarify and better elucidate the potential role of HER2-targeted therapies in RB.