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Accurate grading of pancreatic neuroendocrine tumors (PanNETs) relies on the assessment of Ki-67 immunohistochemistry (IHC). While digital imaging analysis (DIA) has been employed for Ki-67 IHC assessment in surgical specimens, its applicability to cytologic specimens remains underexplored. This study aimed to evaluate an automated DIA for assessing Ki-67 IHC on PanNET cell blocks. The study included 61 consecutive PanNETs and 5 pancreatic neuroendocrine carcinomas. Ki-67 IHC slides from cell blocks were digitally scanned into whole slide images using Philips IntelliSite Scanners and analyzed in batches using the Visiopharm Ki-67 App in a digital workflow. Ki-67 scores obtained through DIA were compared to pathologists' manual scores. The Pearson correlation coefficient of the percentage of Ki-67-stained nuclei between DIA reads and the originally reported reads was 0.9681. Concordance between DIA Ki-67 grades and pathologists' Ki-67 grades was observed in 92.4% (61/66) of cases with the calculated Cohen's Kappa coefficient of 0.862 (almost perfect agreement). Discordance between DIA and pathologists' consensus reads occurred in 5 PanNET cases which were upgraded from G1 to G2 by DIA due to contaminated Ki-67-stained inflammatory cells. DIA demonstrated excellent concordance with pathologists' assessments, with only minor grading discrepancies. However, the essential role of pathologists in confirming results is emphasized to enhance overall accuracy. • Digital imaging analysis (DIA) of cytology cell block Ki-67 immunohistochemistry (IHC) from pancreatic neuroendocrine tumors • Automated digital workflow to analyze Ki-67 IHC whole slide images • Excellent concordance between DIA and pathologists' consensus scoring of Ki-67 IHC [ABSTRACT FROM AUTHOR]

Cell blocks are cytologic preparations that are processed as paraffin embedded blocks in a manner comparable to formalin-fixed paraffin-embedded tissue in surgical pathology. In addition to serving as an adjunct to other cytologic preparations for morphologic diagnosis, cell blocks play an increasingly important role as they yield tissue sections that can be utilized for ancillary testing such as immunohistochemical stains and molecular studies. While essentially universally viewed as playing a pivotal role in cytopathology practice, there are various factors that limit their use in practice and contribute to dissatisfaction with cell block quality. Cell block preparation, as opposed to tissue processing in surgical pathology, is more variable with many different protocols in use today. This review explores the most commonly used cell block preparation techniques currently in use with review of the unique advantages and limitations each method presents. The goal of this work is to serve as a resource that can aid in making more informed decisions about which cell block protocol may work best for individual laboratories. • Cell blocks play a pivotal role in the practice of cytopathology today. • The following review explores the most common cell block preparation methods including preparation methods with modifications with advantages and limitations of each method [ABSTRACT FROM AUTHOR]

We sought to assess the utility of the International System for Serous Fluid Cytopathology (TIS) in the context of our department's routine practice. We examined 1028 archived effusion cytology (pleural, peritoneal, and pericardial) cases from 2018 to 2019, and re-classified them along the international system into the following diagnostic categories: nondiagnostic (ND), negative for malignancy (NFM), atypia cells of undetermined significance (AUS), suspicious for malignancy (SFM), and malignant (MAL). The full distribution of the cases examined was as follows: ND 2.0%; NFM 66.1%; AUS 6.0%; SFM 4.7%; MAL 21.2%. Overall risk of malignancy for each category was calculated as: ND 30.0%; NFM 18.0%; AUS 61.9%; SFM 100%; MAL 94.4%. The overall performance attributes of TIS were as follows: sensitivity 57.1%; specificity 98.3%; positive predictive value 94.4%; negative predictive value 82.0%; diagnostic accuracy 84.5%. The new classification was simple and intuitive to use and our results appear to fall within the expected ranges of the new guidelines, with risk of malignancy and accuracy comparable to similar studies. The availability of a cell block allowed for refinement of the diagnosis in a majority of cases with equivocal cytology, though this was dependent on the cell yield. • We have undertaken one of the largest scale assessments of the International System for Serous Fluid Cytopathology (TIS) with over 1000 archival cases reviewed and re-categorized. • Being a relatively new system, we believe that our study assists in the validation of the TIS, as well as contributing to a still-developing consensus on parameters such as expected rates and risk of malignancy for each diagnostic category. • We are one of the first groups to compare our archival cell block results with the TIS, and demonstrate their predictive value, particularly in the more equivocal atypical and suspicious categories. [ABSTRACT FROM AUTHOR]

Rapid on-site evaluation (ROSE) has been used during the endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) procedure as standard practice. Because of the COVID-19 (coronavirus disease 2019) pandemic, our institute had had to discontinue ROSE and adopt a direct-to-cell block approach. In the present study, we aimed to determine whether this change has had significant effects on the cytopathology quality. A total of 1903 EBUS-TBNA cases from 734 patients were collected (1097 cases with ROSE for 452 patients; 806 cases without ROSE but with direct-to-cell block for 282 patients). The clinical and cytology data were analyzed using SAS, version 9.4, software to render calculated standardized residuals and a fitted multivariate generalized linear model. On average, a biopsy from a patient with ROSE was 0.936 (=exp −0.066) times less likely to be reported as satisfactory compared with a biopsy from a patient without ROSE, although the difference was not statistically significant (P = 0.785). The inadequacy rate of EBUS-TBNA was 6.4% higher on average for cases with ROSE compared with a direct-to-cell block approach. However, this difference was also not statistically significant. The proportions of biopsies reported as diagnostic for malignancy and other were significantly different between the ROSE and no-ROSE groups with a standardized residual of 1.80 (P = 0.036) and −2.27 (P = 0.012), respectively. Discontinuing ROSE and using a direct-to-cell block approach had no negative effects on cytopathology quality. This practice can be considered acceptable during the COVID-19 pandemic when social distancing and the shortage of staff and supplies have resulted in challenges to delivering quality care to cancer patients whose treatment cannot be postponed. • Rapid on-site evaluation (ROSE) has been utilized during the endobronchial ultrasound transbronchial needle aspiration (EBUS-TBNA) procedure is a standard practice. However, due to the COVID-19 pandemic, our institute had to discontinue ROSE and adopted a direct-to-cellblock approach. We were concerned this practice may have significant negative impact on patient care. • A comparison of a total of 1903 EBUS-TBNA cases from 734 patients were collected (1097 cases with ROSE on 452 patients; 806 cases without ROSE/direct-to-cellblock on 282 patients) were carefully studied. • We were relieved to know that so far discontinuing ROSE and using a direct-to-cellblock approach does not cause negative impact on cytopathology quality. Thus, this practice is acceptable during COVID-19 pandemic when social distancing and shortage of staff and supplies presenting challenges to deliver quality care to cancer patients whose care cannot be postponed. [ABSTRACT FROM AUTHOR]

There is no consensus for interpretation of p16 immunohistochemistry (IHC) in cytology preparations. Our study aims to assess p16 IHC staining in formalin-fixed cytology cell blocks (CBs) from head and neck squamous cell carcinoma (HNSCC) fine-needle aspiration (FNA) specimens in comparison with surgical pathology p16 staining and to determine the reproducibility of p16 IHC scoring in CBs. A total of 40 FNAs from 2014 to 2019 of HNSCC with p16 IHC were obtained. CB p16 staining was scored independently by 5 cytopathologists as interval percentages of tumor cell positivity. Receiver operating characteristic (ROC) curves were examined to determine optimal cutoffs for each pathologist based on sensitivity and specificity values. Gwet's coefficient (AC 1) was calculated to assess inter-rater reliability. Greater than 10% was the lowest threshold to reach 100% specificity with high sensitivity (55%-84%) in all 5 raters. Rater performances were similar, with areas under the curve (AUCs) ranging from 0.89 to 0.95. Using the >10% threshold, Gwet's AC 1 = 0.72 (95% CI: 0.56-0.89). Diagnostic performance improved further when low-cellularity cases were excluded, with AUC ranging from 0.94 to 0.99 and Gwet's AC 1 = 0.79 (95% CI: 0.61-0.98). p16 IHC performed on cytology CBs can serve as a surrogate marker for the detection of HPV with high sensitivity and specificity levels. Using a threshold lower than that recommended for surgical pathology for the interpretation of p16 positivity may be appropriate for FNA cytology CB preparations. All cytopathologists in our study displayed reproducible high sensitivity and specificity values at the >10% threshold. • p16 IHC performed on cytology cell blocks can serve as a surrogate marker for the detection of HPV with high specificity and reproducibility (substantial agreement) at a cutoff lower than the surgical pathology threshold of >70%. Our study found that >10% was the lowest threshold to reach 100% specificity with high sensitivity (55%-84%) in all 5 raters. [ABSTRACT FROM AUTHOR]

Oropharyngeal squamous cell carcinoma is associated with human papillomavirus (HPV) and often presents with early metastasis to cervical neck lymph nodes that are amenable to fine-needle aspiration (FNA). The most common method of HPV status determination is p16 immunohistochemistry (IHC). The literature suggests that a lower threshold is needed for p16 positivity on cell block. We examined and quantified p16 IHC staining on cell block and used receiver operating characteristics (ROC) curve analysis to determine an optimal cutoff value with high sensitivity and specificity. Thirty-six FNAs of metastatic squamous cell carcinoma from cervical lymph nodes with p16 IHC were evaluated. The p16 stain was quantified in 5% increments and high-risk HPV mRNA in situ hybridization was performed as a gold standard test. Statistical analysis was performed. Interobserver variability was evaluated and was shown to be low with an intraclass correlation coefficient of 0.857. ROC analysis was performed and showed that a cell block p16 IHC cutoff of 15% yielded the highest sensitivity (80%) and specificity (81.8%). Our data show that a threshold of 15% p16 staining in cell block maximizes sensitivity and specificity. [ABSTRACT FROM AUTHOR]

Fine-needle aspiration (FNA) of nodal metastases plays a key role in the diagnosis of oropharyngeal squamous cell carcinoma (OPSCC). Because of significant clinical implications of human papillomavirus (HPV)-related OPSCC, immunohistochemistry for p16 as a surrogate marker for high-risk HPV is an important ancillary test. After our laboratory switched from CytoLyt to formalin fixative for FNA needle rinses generating cell block (CB) material, we investigated the impact of this protocol change on the accuracy of p16 results. FNA specimens of head and neck lesions with p16 staining performed on CB, from 1 year before and after the implementation of formalin-fixed CB (FCB) were identified. Nuclear and cytoplasmic p16 expression was scored and compared to p16 status on corresponding surgical specimens. There were no false-positive results with either fixative. CytoLyt-fixed CB (CCB) had 47% (7 of 15) false-negative cases, whereas FCB had none, with 100% diagnostic accuracy for p16-negative (n = 6) and p16-positive (n = 15) results. False-negative CCB showed 0% to 10% nuclear and 0% to 65% weak cytoplasmic staining, whereas true-positive CCB showed 10% to 85% nuclear and 35% to 90% cytoplasmic staining. p16-negative FCB showed 0% nuclear and cytoplasmic staining, and p16-positive FCB showed 30% to 100% moderate-strong nuclear and cytoplasmic staining. Interobserver variability was greater with CCB. In our laboratory, formalin fixation of CB material improved the accuracy of p16 interpretation. Staining in FCB was also more robust than CCB, which showed weaker cytoplasmic and more focal nuclear staining. Therefore, we advocate formalin fixation for head and neck cytology specimens that may require p16 testing. • Testing for p16 status is clinically important for oropharyngeal carcinomas. • No established criteria exist for defining p16 positivity in cytology specimens. • CytoLyt fixation of cell block material may lead to false-negative p16 results. • Formalin fixation leads to robust, easily interpretable p16 staining in cell blocks. [ABSTRACT FROM AUTHOR]

Assessment of human papillomavirus (HPV) status is critical to the treatment and prognosis of patients with oropharyngeal squamous cell carcinoma. Patients often present with enlarged cervical lymph nodes which are amenable to fine needle aspiration (FNA) and cell block creation. The most widely used method for assessing HPV status is the surrogate marker p16. Other HPV specific methods such as high-risk HPV E6/E7 mRNA in situ hybridization (ISH) have been shown to perform as well as p16 and are easier to interpret. Our study evaluates the utility of high-risk HPV mRNA ISH in cell block specimens. Thirty-six cases of metastatic squamous cell carcinoma in cervical neck lymph node FNAs were identified over a 3-year period. All cases had p16 immunohistochemistry (IHC) performed on cell block. HR HPV mRNA ISH was performed on the cell block and compared to the p16 results. Additionally, p16 and HR HPV mRNA ISH status was assessed in those cases with corresponding surgical resections. HR HPV mRNA ISH confirmed the p16 IHC (either positive or negative) in 24 of the 36 cases (66.7%). Six false negative cases were p16 negative/HR HPV mRNA ISH positive. HR HPV mRNA ISH was positive in 75% of the four p16 equivocal cases. Two cases were p16 positive/HR HPV mRNA ISH negative. HR HPV mRNA ISH is no more difficult to perform in the IHC lab and is easier to interpret than p16 IHC. HR HPV mRNA ISH is a useful alternative to p16 in cell block specimens. • Accurate assessment of HPV status in cell block has important therapeutic and prognostic implications for patients with oropharyngeal squamous cell carcinoma as cytology specimens may be the first or only tissue received. • While p16 is the most widely used surrogate marker for HPV, variability in interpretation has somewhat limited it's utility in cell block. HR HPV mRNA ISH is HPV specific and easier to interpret. • HR HPV mRNA ISH is a useful alternative to p16 in cell block specimens. [Display omitted] [ABSTRACT FROM AUTHOR]

Thyroid fine-needle aspiration (tFNA) is a powerful screening tool for assessing solitary thyroid nodules. Generally, morphologic evaluation of smears yields an accurate diagnosis; but, in some cases it is useful to have a cell block (CB) to conduct ancillary studies such as immunohistochemistry (IHC). Cytologic diagnoses guide clinical decisions, so it is important that accurate and efficient diagnoses be rendered. Our study evaluates the diagnostic utility of the CB in the evaluation of tFNAs. We performed a retrospective chart review of all tFNA specimens from January 2014 to July 2019. Data collected included TAT (in days), diagnosis, if a CB was prepared, and if it was diagnostically contributory. Descriptive statistics were calculated. Data were analyzed using the χ2 test and the Mann-Whitney U -test. Of the 2321 specimens, 40.2% (933) had CB and only 0.3% (7) were diagnostically contributory. IHC was used for 2 cases. For cases with CB, the median TAT was one day [0-18 days] and the median TAT without CB was 0 [0-9 days]. There was a significant difference in TAT between cases with a CB and those without. Most cases without a CB had same-day TAT (66.4%), whereas only 1.1% of those with a CB had same day TAT. Cases with CB were more likely to have a TAT >1 day (65% versus 12.1%) or >3 days (25.4% versus 10%) than those without a CB (P < 0.0001). We found the diagnostic utility of CB for tFNAs to be very low. The addition of a CB added at least 1 day to the TAT in all diagnostic strata. The additional time causes patients to wait for results, even for nondiagnostic studies. The increased TAT, resources, and manpower use may be reduced if CB were produced only as needed—if the results of the smear were ambiguous or if ancillary tests were needed to confirm the diagnosis. • Of 2321 specimens, 40.2% (933) had cell blocks of which only 0.3% (7) were contributory to the diagnosis. • Median turnaround time for cases with cell blocks was 1 day (range: 0-18 days). • Median turnaround time for cases without cell blocks was 0 days (range: 0-9 days). • Cell block cases were more likely to have a TAT more than one day (65%, P < 0.0001). • Cell block cases were more likely to have a TAT more than 3 days (25.4%, P <0.0001). [ABSTRACT FROM AUTHOR]

The utility of cell block (CB) preparation is well established in cytopathology. Despite 23.3% of College of American Pathologists–accredited laboratories using CB with liquid-based preparations on urine cytology (UC) cases, there are very few studies on their performance. To determine their usefulness, we conducted a retrospective review of UC cases that received CB. We identified 27 UC cases with ThinPrep (TP) and CB preparation between 2016 and 2020 at our institution. Clinical history and follow-up data were compiled. A blinded review of TP alone, and TP together with CB, was performed by 2 pathologists and 2 cytotechnologists. Diagnoses were rendered in accordance with The Paris System for Reporting Urine Cytology. Blood and acute inflammation were common background elements in cases that received CB preparation. In total, CB upgraded the diagnosis in 7 of 27 cases (26%). The maximum utility of CB preparation was seen in indeterminate cases where 60% (6 of 10) were upgraded, including 71% (5 of 7) of atypical urothelial cells (AUC) and 30% (1 of 3) of suspicious for high-grade urothelial carcinoma (HGUC). One case (1 of 12, 8%) diagnosed as negative for HGUC on TP was diagnosed as low-grade urothelial neoplasia on CB. Our results demonstrate that adjunct use of CB preparation aids in a definitive diagnosis on AUC category and may be helpful in cases with cell clusters or tissue fragments, or cases suspicious for HGUC. Further correlation studies are warranted in this area to expand our knowledge about the utility of CBs in urine cytology. • More studies are needed on cell block preparations on urine cytology specimens. • Indeterminate urine cytology cases show the most benefit of cell block preparation. • We highlight many areas for further research on cell blocks in urine cytology. [ABSTRACT FROM AUTHOR]

We performed a comparison of cell blocks prepared with the collodion bag and HistoGel to evaluate the ease of embedding and cutting, performance with low cellularity specimens, time and cost per specimen, and value to support immunohistochemistry and molecular diagnostics. We processed 11 fresh, unfixed effusions using both the collodion bag and the HistoGel cell block preparation methods. Six immunohistochemistry stains were tested on 2 of the body fluids. DNA was extracted and quantified, and polymerase chain reaction cycle thresholds were evaluated from cell blocks prepared from 5 of the body fluids. The comparison parameters included embedding difficulty, cutting resistance, adequacy, cell yield, cell preservation, immunohistochemistry stain quality, DNA quantity, integrity, and purity. The time and cost to prepare each specimen was compared using normalized values for preparation of specimen, cost per year, and cost per specimen. Each parameter was assessed for both cell block preparation methods. All 3 of the samples with moderate or poor cell yield were low-volume (5-mL) samples prepared with the HistoGel method. In contrast, the collodion bag method produced a good yield with all three 5-mL samples. DNA recovery was greater in the collodion bag method. Similar crossing threshold values in purity reactions indicated equally high-quality matrix properties for the collodion bag and HistoGel preparations. Preparation of the specimen was 10 minutes faster with the collodion bag method, and the cost for the collodion bag method was $0.24 more expensive per cell block than using the HistoGel. The collodion bag method produced superior cell blocks for both morphologic and molecular studies more consistently, with lower volume specimens and with less time per specimen. [ABSTRACT FROM AUTHOR]

Introduction Urine cytology is a common non-invasive test to screen for urothelial carcinoma. Urine cell blocks may sometimes be prepared as a diagnostic aid (eg, to characterize architecture or perform immunohistochemistry). The aim of this study was to determine whether routinely preparing cell blocks on urine specimens improves diagnostic sensitivity. Materials and methods Three time periods were compared: time period 1 (prior to November 2009; 1437 consecutive selected cases), when cell blocks were rarely prepared; period 2 (November 2009 to May 2010; 1230 selected cases), when cell blocks were prepared on all cases; and period 3 (after May 2010; 1499 consecutive selected cases), when cell blocks were made only when indicated (for samples with substantial cellular pellets or when requested by a pathologist). Results Patient demographics and the type of specimens received were relatively similar during the 3 time periods. Increased preparation of cell blocks was not accompanied by a notable improvement in specimen adequacy rate, given that <1%, 2%, and 1% of samples were unsatisfactory for the 3 periods. Only the proportion of atypical cases differed during the time periods, being highest in period 1 (23%), but lower in periods 2 and 3. Turnaround time was fastest for period 1 (mean: 47 hours, median: 33 hours), and slower for period 2 and period 3. Conclusion These data show that routinely preparing cell blocks for urine samples did not improve our laboratory's specimen adequacy rate. Nonetheless, cell block preparation on urine samples did help lower the proportion of atypical diagnoses, when routinely or selectively prepared. Because preparation of cell blocks on all urine cases can be costly and only provides minimal added clinical benefit, our recommendation is to rather judiciously utilize cell blocks when screening urine cytology samples. [ABSTRACT FROM AUTHOR]

Introduction Various cell block (CB) preparation methods are utilized by different laboratories, and not all laboratories perform CBs in tandem with ThinPreps (TPs). To compare the performance of different CB methods and their diagnostic value when used in conjunction with TP, we assessed the quantity and size of granulomas obtained from endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) of lymph nodes in the evaluation of granulomatous mediastinal disease. Materials and methods A retrospective analysis of mediastinal lymph node EBUS-TBNA specimens that detected granulomas at our institution was performed. A total of 264 specimens from 124 patients had a TP followed by a CB (either plasma-thrombin, HistoGel, or CellGel) prepared from the residual material in the PreservCyt vial. The number and size of granulomas on each preparation was assessed using digital software. Results Granulomas were detected only on the CB in 18.9% of cases and only on the TP in 5.3%. All 3 CB preparation methods showed significantly more and larger granulomas compared with the paired TP, with the plasma-thrombin and CellGel methods yielding more diagnostic material than the HistoGel method. In addition, the average number of granulomas (4.0 ± 0.4 versus 15.3 ± 1.1) and granuloma size (119.2 ± 3.2 μm versus 271.8 ± 7.3 μm) were significantly lower on TP compared with CB, respectively. Conclusions Plasma-thrombin and CellGel CB preparation methods had a higher granuloma yield compared with the HistoGel method. Additionally, significantly more numerous and larger granulomas were present on CBs compared with TP slides. Therefore, solely relying on TP slide evaluation may unintentionally overlook larger tissue fragments obtained during needle aspirations. [ABSTRACT FROM AUTHOR]

Introduction Evaluation of programmed cell death ligand-1 (PD-L1) on formalin-fixed paraffin-embedded (FFPE) histologic specimens is required for immunotherapy with pembrolizumab in non-small cell lung carcinoma (NSCLC). A significant percent of patients may be diagnosed on cytology samples alone; however, FFPE tissue may not always be available. Here, we evaluated the feasibility of PD-L1 staining on a variety of cytologic preparations including conventional cell blocks (CB), cell-transfer cell blocks (CTCB), and direct smears. Materials and Methods We identified 30 NSCLC cytology cases that had PD-L1 status evaluated on a concurrent core needle biopsy. Papanicolaou-stained smears (PS) were reviewed and a moderately cellular smear was selected per case to prepare a CTCB. CTCB, CB, and PS (when available) were stained with PD-L1 22C3 and tumor proportion scores (TPS) were compared across all preparations with the concurrent core biopsies. Results Concordance of PD-L1 positivity in CB and PS versus core biopsy was high, 80% (12 of 15) and 94.4% (17 of 18), respectively. CTCB versus core biopsy concordance was lower in comparison, 62% (13 of 21) for PD-L1 positivity. Overall, TPS was lower in CTCB compared with CB and PS. Among the 3 preparations, CTCB and CB sections were easier to interpret as PS displayed various artifactual staining patterns. Conclusions In summary, our study demonstrates that CB and PS preparations are suitable surrogates for histologic FFPE tissue for determining PD-L1 status in NSCLC patients. CTCBs, on the other hand, show high discordance and are not optimal specimens. Pre-analytic factors in unconventional cytology preparations may need optimization and negative results should be interpreted with caution. [ABSTRACT FROM AUTHOR]

Introduction The diagnosis of pancreatic ductal adenocarcinoma (PDA) on endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) material is often challenging. An immunohistochemical (IHC) panel may help establish the diagnosis of PDA in cases limited by sample size or ambiguous cytology. S100P, IMP3, and SMAD4 are 3 IHC markers that have shown promise as individual markers for PDA that have never been tested together as a panel. In this study, we evaluated the individual and combined efficacy of S100P, IMP3, and SMAD4 for the detection of PDA. Materials and Methods S100P, IMP3, and SMAD4 IHC staining was performed on cell blocks (CBs) procured from pancreatic EUS-FNA procedures. The cohort included CBs that were diagnostic for PDA (n = 35), suspicious but nondiagnostic for PDA (n = 2), as well as CBs with benign pancreatic ductal epithelium (n = 12) and benign reactive pancreatic ductal epithelium (n = 18). A positive result for IMP3 and S100P was defined as moderate or strong staining of >10% of ductal cells. Complete lack of SMAD4 nuclear staining was considered a positive result—any nuclear SMAD4 staining was considered a negative result. Results Two and 3 IHC marker panels were almost always more specific than individual IHC markers. Positivity for at least 2 of 3 IHC markers was a sensitive (91.89%) and highly specific (100%) marker of PDA. Conclusions The 3 IHC marker panel composed of S100P, IMP3, and SMAD4 is highly specific for PDA. Future studies should evaluate efficacy in a cohort with more atypical and suspicious cases. [ABSTRACT FROM AUTHOR]

Introduction Fluorescence in Situ Hybridization (FISH) for Human Epidermal Growth Factor Receptor 2 ( HER2 ) is traditionally performed on histologic specimens; there are no guidelines for validation of HER2 testing on cytology specimens. Our aim was to correlate HER2 FISH results on cytologic and histologic specimens. Materials and methods A retrospective search was conducted to identify breast carcinomas with HER2 FISH testing on both cytologic and histologic specimens. Results were interpreted using updated 2013 ASCO/CAP guidelines. Results 54 women with HER2 FISH results on both cytologic and histologic specimens were identified. HER2 FISH was performed on 26 formalin-fixed thrombin clot cell blocks, 6 Cellient (Hologic, Inc., Bedford, MA) cell blocks and 22 ThinPrep slides, and was negative in 43 (87%), positive in 8 (15%), and equivocal in 3 (5%) cases. Of 43 negative cytology cases, the histologic specimen was also negative in 40 (93%). Of 8 positive cytology cases, the histologic specimen was positive in 5 (63%). Overall, 48 of 54 cases (89%) had a concordant result. In patients with a discordant result, the average interval between HER2 FISH testing was 7 years. Three of 6 discordant cases showed HER2 genetic heterogeneity. Five patients received adjuvant chemotherapy, 2 received endocrine therapy, and 1 received trastuzumab. Conclusions FISH is reliable for determining HER2 status in cytopathology specimens. Discordant results between cytologic and surgical specimens are uncommon; possible explanations include genetic heterogeneity or inherent molecular changes associated with disease progression and therapies that occur between testing of the primary carcinoma and the metastasis. [ABSTRACT FROM AUTHOR]

Introduction Current approaches to Pneumocystis jirovecii (PCJ) screening on bronchioalveolar lavage samples (BAL) include Gomori/Grocott methenamine silver stain (GMS), toluidine blue O stain, Wright-Giemsa stain, immunofluorescent antibody stain, and polymerase chain reaction. Another method available is PCJ immunohistochemistry stain (PCJ IHC). There are no published series evaluating the efficacy of PCJ IHC in cell block preparation of BAL, we sought to compare GMS versus PCJ IHC at our institution. Materials and methods We performed a retrospective analysis at our institution of all BAL with cell blocks where PCJ IHC and GMS were done simultaneously since March 2015. Results 982 BAL samples were identified from 640 patients (median age: 54 years; range: 1-84 years). For 895 cases, GMS and PCJ IHC were performed simultaneously. PCJ was identified in 14 samples, from 13 patients (2.2% of patients) using PCJ IHC. GMS stains were read as positive in only 6 of these 14 cases (42.8%); in two of those cases, PCJ was easily identified on routine Papanicolaou stains. We repeated GMS staining on those 14 cases following before-schedule maintenance in our Ventana Benchmark Autostainer, identifying 12 cases positive. In addition, a significantly higher number of organisms was seen on repeat GMS (median: 58) than the original GMS (median: 8.7). Nevertheless, a statistically significant higher number of organisms was detected by PCJ IHC (median: 474). Conclusions PCJ IHC performed in cell block is more sensitive and specific than GMS and is a reliable marker when a low number of PCJ organisms are present. [ABSTRACT FROM AUTHOR]

Introduction Human papilloma virus (HPV)-related head and neck squamous cell carcinoma (HNSCC) is a distinct entity with a better prognosis than conventional disease. Therefore, an accurate and reproducible HPV test is needed. Herein, the analytical factors and interpretation of the HPV DNA in-situ hybridization (ISH) test are investigated. Materials and methods We evaluated 63 ultrasound-guided fine-needle aspiration (FNA) HNSCC cases for a semi-quantitative assessment of the ease of interpretation, staining pattern, and highest magnification needed for HPV DNA ISH on cell block and core biopsy. Results A total of 72 HPV DNA ISH tests were performed in 59 (93.6%) cases. Of these, 17 had more than one HPV DNA ISH assays and 4 (6.4%) had no HPV tests. At least one HPV stain was positive in 38 (62.2%) cases. Eleven (28.95%) ISH tests were rated as difficult or moderately difficult to interpret, and 27 (78.05%) were rated as easy or moderately easy. Twenty-four (63.2%) ISH tests demonstrated strong staining and 14 (36.8%) demonstrated weak staining. Twenty-seven (71.1%) stained diffusely, and 11 (29.0%) focally. Twenty-seven ISH tests required 400× or higher magnification for interpretation. Background debris and nonspecific staining were present in 25 (35.7%) and 15 (21.4%) HPV DNA ISH cases, respectively. p16/HPV ISH was discrepant in 4 (7.3%) cases (3 P16+/HPV−, and 1 p16−/HPV+). Conclusions HPV DNA ISH interpretation can be challenging because of focal or weak staining, which requires careful examination at high magnification. An alternate method is needed for DNA ISH−/p16+ cases. [ABSTRACT FROM AUTHOR]

Introduction Controversy remains as to whether Ki-67 labeling on endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) cell blocks (CBs) can be used to grade pancreatic neuroendocrine neoplasms (PanNENs) reliably and what would be the best methodology for doing so. Materials and methods A retrospective search identified cases with both EUS-FNA and correlating surgical pathology (SP) available. 58 CBs (>100 tumor cells) were identified. Ki-67 labeling on CB was counted using both manual count (MC) and digital image analysis (DIA, ImmunoRatio software). The grades determined on CB were compared with those on corresponding SP reports (kappa statistics). The correct grading rates between MC and DIA were compared (McNemar’s test). Total tumor cell number (TTCN, cutoffs: 500 and 2000) was used as a stratification factor (chi-square tests for trend). Results Of 58 cases, the SP grade distribution was 31 grade 1, 23 grade 2, and 4 grade 3. Overall, the grading concordance of CB MC and SP was higher than that of CB DIA and SP (McNemar’s P -value = 0.022). Compared with SP, CB MC correctly graded 69% (40 of 58) [κ = 0.44 (95% CI: 0.21, 0.66)]; CB DIA correctly graded 55% (32 of 58) [κ = 0.19 (95% CI: 0.04, 0.42)]. Grade 1 tumors had the highest concordance. Although the correct grading rate improved as TTCN increased, no statistical significance was found. Conclusion Although Ki-67 labeling on CB can be used to grade PanNENs, limitation exists, particularly for grade 2 tumors. The method of counting makes a difference: MC is more accurate than DIA. The major reasons of discordance include non-tumor cell contamination and insufficient sampling. [ABSTRACT FROM AUTHOR]

Introduction Cell block (CB) preparations of fine-needle aspirates (FNAs) are utilized for patient management, which requires retention of representative material on slides. Personalized medicine demands quality CB specimens. There is no standard protocol for CB preparation, often resulting in suboptimal slides. The utility of using two CB slides in lymph node (LN) FNA cases was investigated. Materials and methods We cut 10 serial sections from each CB, slides 1 and 5 are stained and considered the first and second cuts, respectively; the remaining slides are reserved for ancillary studies. Hematoxylin and eosin–stained CBs of 221 consecutive LN FNA cases were reviewed; qualitative and quantitative assessment of diagnostic value was made on sections 1 and 5. Results Of the 221 cases, 46.1% (102) had comparable diagnostic cellularity (equally representative) on both slides, whereas 26.7% (59) and 27.1% (60) had more representative material on the first and second cuts, respectively ( P = 0.52). Differences between the representativeness of first and second CB cuts of intrathoracic lymph nodes were minor (n = 192, P = 0.065). Differences between the first and the second slide representativeness of superficial (n = 22, P = 0.98) and intra-abdominal lymph nodes (n = 7, P = 0.38) are limited because of small sample sizes. Conclusion One CB cut can be suboptimal for diagnosis. In our study, inclusion of a second slide increases equal representativeness from 46.1% to 73.2%. These limited observations recognize the need for additional investigations regarding the collection and preparation of CBs. [ABSTRACT FROM AUTHOR]

Introduction For fine-needle aspiration (FNA) biopsy, the cell block is used for precision ancillary diagnostic tests and personalized molecular evaluation. It is important to maximize quality cell blocks. Rapid on-site evaluation (ROSE) provides specimen adequacy and guides cell block collection. The study examines how immunohistochemistry (IHC) utilization correlates with cell block quality and the impact of ROSE on cell block quality. Materials and methods The pathology database identified consecutive FNA biopsy cases with cell blocks. Procedural data and reporting elements were collected including ROSE, adequacy and diagnosis categories, and IHC. Each archived case was reviewed. Cell block cellularity quality scores were categorized as <10%, 10% to 25%, and >25%. Various data points were correlated with the cell block quality score. Results The ROSE cohort had a higher group score of 38.8% versus 26.3% for non-ROSE. Low scores on cell block quality were higher with the unsatisfactory and indeterminate groups (85.2% and 78.5%). A higher grouping score was 3× as likely for a satisfactory as an unsatisfactory group (46.5% versus 14.8%). Positive cases with IHC had higher cell block quality scores compared with those without IHC (56.7% versus 33.2%). Conclusions It is important for pathologists to contribute to improving FNA biopsy cell block quality. This series shows that higher cell block quality provides better utilization for IHC assessment and for IHC testing in positive diagnostic category cases. Providing ROSE service can improve cell block quality and an assurance of a satisfactory FNA biopsy significantly contributes to improved cell block quality. [ABSTRACT FROM AUTHOR]