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Giant cell tumour (GCT), also known as osteoclastoma, is an osteolytic tumour. It involves the epiphyseal and metaphyseal regions of long bones in adults. Rarely these may occur in pediatric patients as well as involve uncommon locations such as sternum, pelvis and occasionally, rib bones. We present a rare case of GCT arising from a rib in a child, diagnosed on fine needle aspiration.

Background Cholangiocarcinoma is a relatively rare form of adenocarcinoma which may resemble adenocarcinoma of pancreatobiliary origin or adenocarcinomas from many other sites in the body. As a result, its distinction relies mainly on clinical history and morphology. Case A 64-year-old male with cirrhosis and worsening liver failure underwent fine needle aspiration of a radiologically detected liver mass. Cytological material showed a monomorphic population of cells arranged in clusters and singly, reminiscent of a neuroendocrine tumor (NET). Cell block morphology added to the diagnostic dilemma by showing a delicate vasculature among the tumor cells. Immunohistochemistry (IHC) on cell block revealed that cells were positive for CK7 and CK19 and negative for synaptophysin and chromogranin, thereby pointing towards pancreatobiliary origin for the tumor and excluding an NET. Conclusion In case of liver aspirates, even when encountering confusing morphological entities, it is imperative to keep in mind the possibility of a rare neoplasm like cholangiocarcinoma. In the absence of core needle biopsy, cell block sections prepared from aspirated material can provide appreciable immunohistochemistry results to resolve the diagnostic dilemma.

Ewing sarcoma (ES) is the second most common bone malignancy in young patients, with 80% occurring in the first two decades of life. In contrast, extraskeletal ES accounts for approximately 12% of cases and is more common in older patients.[1] The clinical behaviour is aggressive, with a 5-year survival of 70-80% for localized disease, less than 30% for metastatic or early-relapsing disease, and possibly a worse prognosis in adults compared to children.[1,2] ES is defined by FET-ETS family gene fusions. The majority of cases harbour t(11;22)(q24;q12) translocations, corresponding to EWSR1-FLI1 fusion (85%), or t(21;22)(q22;q12) resulting in EWSR1-ERG (10%).[1] Herein we report the case of an FUS-ERG fusion-positive extraskeletal ES, which exhibited an indolent natural history over 25 years without any intervention, diagnosed via endobronchial ultrasound-guided fine-needle aspiration (EBUS-FNA) biopsy following progression.

BACKGROUND Solitary fibrous tumour (SFT) is a unique mesenchymal neoplasm with classic features on histology and is characterised by the NAB2-STAT6 gene fusion. There are rare reports of SFTs with pancreatic involvement and only two cases in the literature reporting its features by preoperative fine needle aspiration (FNA). Herein, we characterise the cytomorphological features of four SFTs involving the pancreas by FNA to establish a preoperative diagnostic approach. METHODS The anatomic pathology archives of two academic medical centres were searched to identify patients with a pancreatic FNA cytology specimen and a confirmed diagnosis of SFT by surgical resection. The clinical history, pathological diagnosis, cytomorphological findings, and results of immunohistochemistry (IHC) were reviewed. RESULTS Four SFTs were identified from four patients with a median age of 59 years. The morphological features were variable but most frequently showed a bland spindled-to-epithelioid proliferation in fragments and single cells with small, oval, elongated, and hypochromatic nuclei in a haphazard arrangement with or without dense collagen. One tumour presented with a concurrent metastasis and showed a pure epithelioid component with necrosis and enlarged, hyperchromatic nuclei with conspicuous nucleoli and scattered mitoses. IHC was necessary for all diagnoses which were confirmed by surgical resection. CONCLUSIONS SFTs with pancreatic involvement are rare, and non-specific features and tumour heterogeneity can pose a diagnostic challenge on FNA; however, IHC can be used to make a definitive diagnosis. As a result, FNA is a simple, safe, cost-effective, and accurate approach that can be used to diagnose SFT in the pancreas.

INTRODUCTION Lymph node fine needle aspiration (LN-FNA) is a minimally invasive method of evaluating lymphadenopathy. Nonetheless, its use is not widely accepted due to the lack of guidelines and a cytopathological categorisation that directly relates to management. We report our experience with LN FNA at a large Cancer Center in Latin America. METHODS We retrospectively collected cytological cases of lymph node FNA from the department of pathology at AC Camargo Cancer Center performed over a 2-year period. Data extracted included LN location, age, sex and final cytological diagnosis. Patients that had undergone neoadjuvant chemotherapy and/or cases for which the surgery specimen location was not clearly reported were excluded. For those cases with surgical reports, risk of malignancy was calculated for each diagnostic category, along with overall performance of cytology. False positive cases were reviewed to assess any possible misinterpretation or sampling errors. RESULTS A total of 1730 LN-FNA were distributed as follows: 62 (3.5%) non-diagnostic (ND); 1123 (64.9%) negative (NEG), 19 (1.1%) atypical (ATY), 53 (3.1%) suspicious for malignancy (SUS), and 473 (27.3%) positive (POS). Surgical reports were available for 560 cases (32.4%). Risk of malignancy (ROM) for each category was 33.3% for ND, 29.9% for NEG, 25% for ATY, 74.2% for SUS and 99.6% for POS. Overall sensitivity, specificity, negative predictive value (NPV) and positive predictive value (PPV) were 78.5%, 99.4%, 70.2% and 99.6%, respectively. CONCLUSION Lymph node FNA is a very specific and accurate exam, which is reliable in the detection of lymph node metastasis and other causes of lymphadenopathy.

Oesophageal schwannoma is an extremely rare benign neoplasm. Cytological diagnosis of oesophageal schwannoma has been sporadically reported in the literature. Herein, we present a case of oesophageal schwannoma in an older woman that could be accurately diagnosed based on endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) cytology accompanied by cell block immunocytochemistry.

Introduction The cytopathology and diagnostic accuracy of salivary gland (SG) polymorphous adenocarcinoma (PAC) is the subject of a limited number of reports. We undertook a review of our experience with fine needle aspiration (FNA) biopsy and PAC. Materials and methods A search was made of our cytopathology files for PAC cases that also had histopathological confirmation. FNA biopsy smears and cell-blocks were performed and examined using standard techniques. Results Eight FNA biopsy cases of histologically proven PAC from 7 patients [F:M = 1.3:1, age 39-75 years, mean = 58] met study inclusion. Metastatic aspirates were most common (4), followed by 3 primary cases and 1 locally recurrent neoplasm. Primary FNA sites included hard palate (1 case), lip (1), and lateral tongue (1); all metastatic sites were in the neck. A precise cytologic diagnosis was made in 38% of cases; however, when applying the Milan classification system, 100% could be categorised as either malignant or of uncertain malignant potential. Ancillary immunohistochemical testing performed in 44% of the cases was non-specific. Cytologic smears showed cellular uniformity and structural variety of cell groups with tubular, branching, cribriform, and convex patterns as well as variable, but occasionally abundant globular myxoid stroma leading to confusion with adenoid cystic carcinoma. Conclusion The imitative cytopathology of PAC with other SG neoplasms as well as its infrequency in routine FNA biopsy practice makes specific interpretation difficult, but using a classification system allows for appropriate patient management. Molecular testing in future specimens holds promise for enhancing diagnostic accuracy.

OBJECTIVE Rapid on-site evaluation (ROSE) is a fine needle aspiration (FNA) technique for ensuring sampling adequacy and triaging samples. The Milan system for reporting salivary gland cytopathology (MSRSGC) is a standardised reporting system which aims to improve risk stratification. There is scant literature on the diagnostic value and agreement of MSRSGC on ROSE with final cytological diagnosis in salivary gland FNAs. We aimed to assess the concordance of MSRSCG categorisation and diagnosis on ROSE with final cytological and histological diagnosis. METHODS This prospective study included consecutive salivary gland FNAs for which ROSE was performed over a six-month period. MSRSGC category and diagnosis on ROSE were compared with the final cytological diagnosis and MSRSGC category, and histopathological diagnosis, where available. RESULTS Sixty salivary gland aspirates were included. The adequacy rate with ROSE was 100%. Using the MSRSGC classification during ROSE, 26 (43.2%) samples were categorised as benign neoplasm, 21 (35%) as malignant neoplasm, 9 (15%) as non-neoplastic, and one each (1.7%) belonged to the remaining four categories. MSRSGC categorisation on ROSE concurred with final the cytological diagnosis in 58/60 cases (96.7%). Discrepancies in MSRSGC categories on ROSE included one atypia of undetermined significance with final report as non-neoplastic, and one non-diagnostic as suspicious for malignancy. Good correlation of MSRSGC categories on ROSE with final histopathological diagnosis (88.9% concordance) was also noted. CONCLUSIONS MSRSGC on ROSE shows good concordance with final cytology and histopathology diagnosis, indicating that categorisation according to MSRSGC has utility in ensuring that adequate material is obtained and triaged appropriately for the diagnosis of salivary gland aspirates.

Intraocular metastases from the lung are a common occurrence and an important differential for cytopathologists reading fine needle aspiration biopsies (FNAB). It is a particularly challenging diagnosis when the patient has had no previous diagnosis of lung cancer. We present two cases of intraocular metastases from lung primaries, and we discuss the clinical, radiological, and cytopathological features that help differentiate intraocular metastases of lung primary from other intraocular tumours, in the setting of FNAB. We also discuss the importance of recognising the spectrum of FNAB cases that can be seen specific to an institution, which may vary according to different patient populations. A thorough metastatic workup and ancillary testing, such as IHC or molecular genetics, ensures an accurate diagnosis.

Purpose To investigate the diagnostic accuracy of a different sample preparation protocol for fine needle aspiration cytology (FNAC) of thyroid nodules established during the COVID‐19 pandemic. Methods From April 2020, conventional smears during FNAC were ceased according to World Health Organization recommendations due to the increased infection risk for operators, and a new protocol using only liquid‐based cytology (LBC) was adopted. FNACs performed between April and July 2020 (COVID‐19 group) were retrospectively compared with those from December 2019 through March 2020 (Pre‐COVID‐19 group). The distribution of diagnoses based on SIAPEC‐IAP categories and the concordance between cytological and histological results were compared using the chi‐squared test. Results Categories based on FNAC for 90 and 82 thyroid nodules in the Pre‐COVID‐19 and COVID‐19 groups showed no significant difference in distribution (P = .081), with the following respective cases (and percentages): TIR1, 7 (8%) and 8 (10%); TIR1C, 0 (0%) and 6 (7%); TIR2, 59 (66%) and 55 (67%); TIR3A, 8 (9%) and 5 (6%); TIR3B, 1 (1%) and 2 (3%); TIR4, 5 (6%) and 1 (1%); and TIR5, 10 (12%) and 5 (7%). Among patients with potentially malignant lesions, surgery was performed for 12/16 (75%) nodules in the Pre‐COVID‐19 and 7/8 (88%) nodules in the COVID‐19 groups, with no significant differences between cytological and histological diagnoses (P = .931). Conclusion The new LBC‐only protocol provided similar diagnostic accuracy in comparison with conventional smears, and can be effectively applied during a viral pandemic improving operator safety., The aim of this work was to investigate the diagnostic accuracy of a new sample preparation protocol for FNAC of thyroid nodules established during the COVID‐19 pandemic and to compare it with the diagnostic accuracy of the previously established standard protocol.

OBJECTIVE Endoscopic ultrasound (EUS) is the main tool for biopsy via fine needle aspiration (FNA) from gastrointestinal (GI) lesions including pancreatic, upper gastrointestinal, and adjacent lesions. The variable diagnostic yield and delay until the final pathological results can affect treatment planning and cause patient anxiety. We aimed to assess the agreement of rapid on-site evaluation (ROSE) of EUS-FNA with the surgical histological diagnosis of patients who underwent resection. METHOD A retrospective study was performed including all patients 18 years or older who underwent EUS-FNA with ROSE for GI lesions. For patients who underwent surgical resection, the correlation between ROSE and the surgical histological diagnosis was evaluated with the kappa coefficient. RESULTS Overall, 73 patients who underwent EUS-FNA with ROSE were included, of whom 22 (30.1%) had curative resection. The final pathological diagnosis from surgery showed 17 malignant and 5 benign lesions. Among the benign lesions, ROSE correctly identified 2 (diagnostic accuracy of 40%), while among the malignant lesions, ROSE correctly identified 14 (diagnostic accuracy of 82.4%), yielding a fair kappa coefficient of 0.366 (95% CI 0.035-0.697). When classifying the lesions as either malignant vs benign or suspicious of malignancy, the kappa coefficient increased to 0.58 (95% CI 0.180-0.975) for the subgroup of pancreatic lesions, with diagnostic accuracy of 81.2% for the malignant category. CONCLUSIONS A high level of agreement for malignancy was found between FNA-EUS with ROSE and the final surgical histological diagnosis. ROSE can be used as an adjuvant diagnostic tool to optimise patient management and decrease delay-related anxiety.

OBJECTIVE We aim to evaluate the impact of ThyroSeq® in the management of indeterminate thyroid nodules (ITN), including Bethesda III and IV nodules. METHODS ITNs that underwent ThyroSeq testing between 2016 and 2019 were retrospectively reviewed. A control cohort included ITNs without molecular testing. Cytological, molecular, and histological data were collected. RESULTS We identified 202 ITNs that underwent molecular testing (128 in Bethesda III and 74 in Bethesda IV). Mutations were found in 58 nodules with mutation rates of 21.9% in Bethesda III and 40.5% in Bethesda IV. In this cohort, 49 cases had surgical resection with a resection rate of 24.3% (49/202, 15.6% in Bethesda III and 39.2% in Bethesda IV). Among the resected cases, 42 cases had positive molecular results. Thyroid cancer was diagnosed in 21 nodules with a malignancy detection rate of 10.4%. In the other cohort, we identified 236 ITNs (158 in Bethesda III and 78 in Bethesda IV). Surgical resection was performed in 127 cases, with a resection rate of 53.8% (127/236, 46.2% in Bethesda III and 69.2% in Bethesda IV). Thyroid cancer was diagnosed in 21 nodules, with a malignancy detection rate of 8.9%. The risk of malignancy (ROM) recalculated based on positive ThyroSeq results was significantly higher (21.4%-35.5% in Bethesda III and 50%-60% in Bethesda IV) than that without molecular testing (4.4%-9.6% in Bethesda III and 17.9%-25.9% in Bethesda IV). CONCLUSION We concluded that ThyroSeq significantly decreased the surgical resection rate (from 53.8% to 24.3%) without significantly affecting the malignancy detection rate in ITNs. Furthermore, positive molecular testing significantly increased ROM in ITNs. We believe that the recalculated ROM should be incorporated into the management of ITNs.

Objectives The practice of cytopathology has evolved over the past decade with a growing need for doing more with less tissue. Changes in clinical practice guidelines and evolving needs in tissue acquisition for diagnosis and treatment have affected various areas of cytopathology in different ways. In this study, we evaluated the changing trends in cytopathological practice at our institution over the past decade. Methods We performed a retrospective review of our institutional database for cytopathology cases from calendar years 2009 (n = 28038) and 2019 (n = 31386) to evaluate the changing trends in practice. Results The overall number of exfoliative cases decreased 10% over the past decade, primarily due to a 64% decrease in gynaecological Pap testing. However, the volume of serous body cavity and cerebrospinal fluids increased 125% and 44%, respectively. The overall volume of fine needle aspiration (FNA) cases increased 38% from 2009 to 2019. The number of FNA cases increased across most body sites, driven primarily by a 180% increase in endobronchial ultrasound-guided transbronchial needle aspiration cases. In contrast, breast FNA volume decreased 43%. Ancillary studies increased substantially over the past decade, including immunostains (476%) and molecular testing (250%). Conclusions The trends in our cytopathological practice showed an increased volume of cases, especially in non-gynaecological specimens. As expected, the number of FNA cases used for immunostains and molecular testing increased substantially, indicating an upward trend in ancillary studies in cytopathological practice.

Background Intraductal papillary mucinous neoplasm (IPMN) constitutes up to 20% of all pancreatic resections, and has been increasing in recent years. Histomorphological findings of IPMN are well established; however, there are not many published papers regarding the cytological findings of IPMN on fine needle aspiration (FNA) specimens. We review the cytomorphological features, molecular profile, imaging findings, and prognosis of IPMN. Methods The English literature was thoroughly searched with key phrases containing IPMN. Observations IPMN is a rare entity, affecting men and women equally and is usually diagnosed at the age of 60-70 years. The characteristic imaging features include a cystic lesion with associated dilatation of the main or branch pancreatic duct, and atrophy of surrounding pancreatic parenchyma. Cytomorphological features of IPMN include papillary fragments of mucinous epithelium in a background of abundant thick extracellular mucin, a hallmark feature. IPMNs should be evaluated for high-grade dysplasia, which manifests with nuclear atypia, nuclear moulding, prominent nucleoli, nuclear irregularity, and cellular crowding. Molecular profiling of IPMN along with carcinoembryonic antigen and amylase levels is useful in predicting malignancy or high-grade dysplasia arising in IPMN. Overall, the prognosis of IPMN is excellent except in those cases with high-grade dysplasia and malignant transformation. Postoperative surveillance is required for resected IPMNs. Conclusion IPMN requires a multidisciplinary approach for management. Cytomorphological findings of IPMN on FNA, in conjunction with tumour markers in pancreatic fluid cytology and imaging findings, are of paramount importance in clinical decision-making for IPMN.

Objective Endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) is an essential tool in the diagnosis of pancreatic lesions. The aim of this study was to evaluate the diagnostic accuracy of cytology from EUS-FNA, to correlate the results with the corresponding histopathological diagnoses and to analyse the impact of retrospective assignment of the Papanicolaou Society of Cytopathology (PSC) reporting system categories. Methods All pancreatic FNA specimens reported at the Royal Free Hospital during a 2-year period were retrospectively collected and assigned to the PSC system categories. Any available corresponding histological samples were assessed for concordance. Results In total, 236 cytology specimens from 223 patients were identified, of which 108 (45.8%) had corresponding histology samples. The main reason for cyto-histological discrepancy was sampling error. Interpretive error was identified in one case. Overall, sensitivity was 92.5%, specificity was 100%, diagnostic accuracy of cytology was 95%, false-positive rate was 0% and false-negative rate was 7.5%. The implementation of the new reporting system reduced the number of cases in the atypical category. All cases previously categorised as suspicious or malignant remained in the same category. Conclusions EUS-FNA is an accurate method for evaluating pancreatobiliary lesions. The implementation of the Papanicolaou Society of Cytopathology diagnostic system enhances standardisation of the reporting terminology and reduces the number of samples in the non-standardised and equivocal atypical category.

INTRODUCTION This retrospective morphological study compared the results of fine needle aspiration (FNA) cytology, haematoxylin-eosin (HE)-stained samples and immunohistochemical (IHC)-stained core needle biopsy (CNB) histology samples for primary non-small cell lung cancer (NSCLC) subtyping. We assessed the diagnostic utility of these methods to investigate the contribution of each method to NSCLC subtyping. We also identified the point at which NSCLC subtyping could be performed using histomorphology alone without IHC. METHODOLOGY Concurrent FNA and CNB specimens obtained via a single computed tomography-guided procedure and diagnosed as NSCLC in the Pathology Department of our university within 3 years were reviewed. The results of FNA samples, HE-stained biopsies and IHC-stained biopsies were compared according to subtype. RESULTS A total of 141 subjects were enrolled in the study. For subtyping, FNA provided an accurate diagnosis in 70 (55.1%) of 127 eligible subjects after the exclusion of 14 cases determined as not otherwise specified. CNB histology without IHC achieved a diagnosis in 53 (41.7%) of 127 subjects, which was a significant difference (P

Introduction The Afirma test has been used in the diagnosis of cytologically indeterminate thyroid nodules to reduce diagnostic uncertainty and unnecessary surgeries. Gene Sequencing Classifier (GSC) was developed to improve the positive predictive value and overall test performance of Gene Expression Classifier (GEC). Here we present our experience comparing the performance of first-generation assay of Afirma (GEC) with the new assay (GSC). Methods Retrospective analysis was performed on all Bethesda III and IV cytology thyroid nodules tested with GEC and GSC. Test performance was evaluated by surgical pathology outcomes. Results In total, 167 cases were tested with GEC, of which 49% were reported as benign. Fourteen cases had surgical follow-up with 11 benign, one non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) and two malignant diagnoses. Of the 167 cases, 51% had suspicious GEC result. Fifty-seven of these suspicious GEC cases had surgical follow-up with 28 benign, nine NIFTP and 20 malignant histology. There 133 cases tested with GSC, of which 61% were reported as benign. Ten cases had surgical follow-up, all of which showed benign results and 32% of the cases were tested as suspicious. Thirty-six cases with suspicious GSC had surgical follow-up. Fourteen of them had benign, five NIFTP, and 17 malignant surgical pathology. Based on molecular testing, surgical resection could have been be prevented 61% with GSC, compared to 49% with GEC test. Conclusion Our experience shows that GSC has a better test performance than GEC. Also, our data support that GSC identify more cases as benign and reduces the number of unnecessary surgeries compared to GEC.

Introduction Fine needle aspiration is a well-established technique for evaluating primary and secondary bony lesions. With use in selected cases, it achieves a diagnostic yield comparable to biopsies. Methods Cases of osteosarcoma (OS) with available histological follow-up were retrieved over a 10-year period. Detailed morphological evaluation was done, with special emphasis on pitfalls in the diagnosis of OS on cytology and the various variants of OS. Results Of the 41 cases with available follow-up histology, 56% were correctly diagnosed as OS on cytology. The most common false-negative cytological diagnosis of OS, in 17% cases, was giant cell tumour. The possible explanations for this included low cellularity, minimal atypia, absence of typical osteoid, misinterpretation of metachromatic osteoid material as fibro-collagenous material and non-availability of radiology at time of aspiration. Conclusion A triple-phase evaluation including clinical evaluation, appropriate radiological correlation and cytology/histopathology, is important to clinch an accurate diagnosis.

A 35-year-old male, presented with a slow growing painless cutaneous nodule of 1.5 cm size of 6-month duration. On local examination, single well defined, freely mobile, non-tender skin nodule was found over the dorsum of right hand. Fine needle aspiration of the swelling yielded particulate material. The cytosmears were highly cellular and showed three population of cells comprising of cohesive clusters of larger cells, discretely lying larger cells and smaller lymphocyte like cells. (Figure 1) The cohesive cells were larger with round nuclei, pale chromatin and moderate amount of cytoplasm. Focal rosette like arrangement were noted. The larger scattered cells were in the form of naked nuclei with fragile cytoplasm giving a glycogenated appearance to the background. The third population of cells comprised of smaller cells with a coarsely clumped clock face appearing chromatin resembling lymphocytes. There was no mitosis, nuclear atypia or necrosis. (Figure 2).

Objective To compare the frequency of fine needle aspiration (FNA) cytological results between nodules 1 cm or less and nodules greater than 1 cm. Methods All FNAs performed between January 2016 and December 2019 at an institute in Brazil were analysed. For each nodule, at least two conventional slides were produced (one stained by Giemsa and the other by hematoxylin and eosin). All cases were reviewed by two cytopathologists and were reported following the Bethesda System. Clinical information (gender and age) and ultrasound data (nodule size and location) were collected. The magnitude of association was measured using the prevalence ratio (PR) with 95% confidence intervals (CIs) considering two groups of nodules: 1.0 cm or less, and greater than 1 cm. Results A total of 3703 nodules were analysed from 3265 patients (2906 women [88.48%], 359 men [11.51%], with a combined mean age of 52 years). Considering the prevalence ratio of Bethesda categories between these two groups of nodules, the nondiagnostic or unsatisfactory category (PR: 3.0, 95% CI: 2.2-4.2) and the suspicious for malignancy category (PR: 1.6, 95% CI: 1.1-2.4) were significantly associated with nodules measuring 1 cm or less. Conclusion Our results demonstrated that nodules 1 cm or less are significantly associated with the nondiagnostic and suspicious for malignancy categories of the Bethesda System when compared to nodules greater than 1 cm.

OBJECTIVE The goal of this study was to evaluate the performance of p16 staining in cell-blocks vs tissue specimens as a surrogate marker for human papillomavirus (HPV) status in oropharyngeal squamous cell carcinomas. METHODS Head and neck squamous cell carcinoma cases presenting as a neck mass with a p16 result on cytology and corresponding tissue specimens (1 January 2014 to 30 June 1920) were included in the study. The following were assessed from cell-block material: number of tumour clusters, percentage of tumour cells with p16 staining, and presence of staining in clusters vs single cells. Results were compared to tissue p16 status. Results of any other ancillary HPV testing were also noted. RESULTS Forty-two head and neck squamous cell carcinoma neck metastases (35 oropharyngeal, five non-oropharyngeal, and 2 unknown primaries) were identified. The p16 staining pattern in cell-blocks was seen in single cells (27.6%), clusters (44.8%), or both (27.6%). The percentage of tumour cells staining for p16 in cell-blocks was much lower than in corresponding tissue specimens. There were four false negatives and one false positive (concurrent HPV DNA polymerase chain reaction testing was positive in cytology and surgical material). CONCLUSIONS Compared to tissue, the cut-off for p16 interpretation in cell-blocks is substantially lower and staining may be present in single cells or clusters. In 96.9% of cases, any p16 staining in cell-blocks correlated with positive p16 staining in surgical specimens. However, a negative or discrepant p16 result on cell-block should prompt confirmatory HPV studies, as false negative p16 staining in cell-blocks is high.

Introduction The American Society of Clinical Oncology (ASCO)-endorsed College of American Pathologists guideline recommends high-risk human papillomavirus (HPV) testing for metastatic squamous cell carcinoma (SCC) of lymph nodes level II/III of unknown primary. Herein, the performance of HPV-RNA in situ hybridisation (ISH) in detection of HPV-related SCC is evaluated implementing the ASCO guideline recommendations. Methods Eighty head and neck (HN) SCC fine needle aspirations, which utilized HPV-RNA ISH/P16, were evaluated at Johns Hopkins Hospital (2015-2018) to investigate their performance and concordance with histology. The results were compared to a prior study of 59 HNSCCs, which HPV-DNA ISH. Results Of the 80 reviewed fine needle aspirations, 65 (50 male, 15 female) were included. The mean age was 63.2 ± 14.0 years. The most common site was neck lymph nodes (47, 72.3%). Fifty-five cases (84.6%) were accompanied by concurrent core biopsy, and 48 cases (59.4%) had surgical follow-ups. HPV-RNA ISH was positive in 44 (67.7%), and P16 was strongly positive in 46 (70.8%). The HPV-RNA ISH/ P16 concordance rate was 92.3% on cytology material. The cytology/surgical concordance rate for HPV-RNA ISH was 88.9% (16/18). There was a discordance between the results in five cases (7.7%; HPV-RNA ISH-/P16+). Conclusion HPV-RNA ISH is a robust and reliable method for detecting HPV-related HNSCC on cytology material showing concordance rate of 92.3% between HPV-RNA ISH and P16, which is a sensitive but non-specific marker. Compared to HPV-DNA ISH, HPV-RNA ISH reproducibly identifies HPV-related HNSCC with fewer discrepancies between cytology and histology. The findings of this study are in agreement with the ASCO recommendations.

Introduction The purpose of this study was to clarify the clinicopathological features of patients with false-negative fine needle aspiration cytology (FNAC) and to determine the factors associated with negative FNAC. Methods Patients with negative FNAC from January 2010 to December 2019 were included. The patients with positive sentinel nodes (SN) were divided into two groups: micrometastasis (≤2 mm) group and macrometastasis (>2 mm) group. The clinicopathological characteristics were compared between the two groups using the χ2 test. Results A total of 165 patients with negative FNAC were included; 52 (31.5%) had positive SNs. Of the 52 patients, 13 (25%) had micrometastasis and the remaining 39 (75%) had macrometastasis. Of the 113 patients with negative SNs, none had metastases found in non-SNs. No significant differences were observed in age, cT stage or subtype, and preoperative ultrasound findings between the two groups. Conclusions The false-negative rate of FNAC was high (31.5%). Micrometastatic disease was seen in patients with negative FNAC, and this might be the cause of false-negative FNAC results.

Objectives The accuracy of a cytological diagnosis obtained by fine needle aspiration is influenced by several factors including the technique used and the experience of both the aspirator as well as the cytologist. In this project we planned to evaluate the interobserver differences of thyroid nodule cytopathology in our medical centre. Methods The study was conducted using retrospective pathology reports from a single academic centre from August 2013 to September 2017. We compared the sensitivity, specificity, negative and positive predictive values, malignancy rates, and accuracy of two cytopathologists who evaluated thyroid nodules. Results We included 287 fine needle aspirations of thyroid nodules in the study. Approximately one fifth (18.5%) of patients had surgery and the rate of malignancy was 40%. There was a similar frequency of use of all thyroid Bethesda system (TBS) categories with the exception of TBS 3 (8.0% and 21.2%, P = .01). As a consequence, the malignancy rate was different in TBS 3 category (40% vs 17%, P = .545). Conclusions There are interobserver differences in the evaluation of thyroid nodules. Clinicians should be aware of such differences because they affect the malignancy rate in each TBS category.

Background Fine needle aspiration (FNA) is a routine sampling method in the diagnostic work up of salivary gland lesions. Despite universal use, no standardised classification existed for the cytopathological reporting of such entities until recently. The Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) aims to standardise the reporting of these lesions, offering risk of malignancy rates and clinical management recommendations. Methods We retrospectively applied MSRSGC to cases reported over a 5-year period. Salivary FNA specimens were reclassified according to the MSRSGC as (I) non-diagnostic, (II) non-neoplastic, (III) atypia of undetermined significance (AUS), (IV) benign neoplasm and salivary gland neoplasm of uncertain malignant potential, (V) suspicious for malignancy, and (VI) malignant. Cases with surgical resections were documented and risk of malignancy calculated for each group, where possible. We compared our outcomes with similar studies performed since publication of the Milan criteria. Results In total, 192 specimens were reassigned as non-diagnostic (n = 30), non-neoplastic (n = 31), AUS (n = 1), benign neoplasm (n = 97) and salivary gland neoplasm of uncertain malignant potential (n = 4), suspicious for malignancy (n = 3), and malignant (n = 26). There were 73 surgical resections. Our calculated risk of malignancy was within the proposed MSRSGC rates for the non-diagnostic, benign neoplasm and malignant groups. One AUS case did not undergo surgery. Benign and malignant sensitivities and specificities for the original reporting categories were 88.24% and 95.72%, and 100% and 95.45% for the MSRSGC, respectively. Conclusion Salivary gland FNA has high diagnostic accuracy and the MSRSGC offers standardised reporting and assistance in the stratification of cases. This may improve communication between pathologists and clinicians with improved outcomes for patients.

INTRODUCTION The UK Royal College of Pathologists (RCPath) Thy terminology is an internationally recognised system for reporting thyroid fine needle aspiration. The terminology has been used throughout the UK and Ireland, in some parts of Italy and Switzerland, and elsewhere in the world. There is no systematic review of the literature specifically addressing the use of the non-diagnostic for cytological diagnosis-Thy1/Thy 1c category in the UK RCPath terminology. METHODS A comprehensive literature search of online databases was conducted in October 2019 specifically examining overall reported rates of Thy1 and Thy1c in aspirates classified according to the UK Thy terminology. RESULTS Twenty-five articles were identified showing a Thy1 rate of 13.4% (2540/18 920). The studies were then stratified according to whether or not the patients underwent rapid on-site evaluation (ROSE): 6.0% (353/5841; range 3.0%-10.9%) of ROSE aspirates were Thy1 whereas 18.5% (2072/11 204; range 7.9%-43.3%) of non-ROSE patients were Thy1; (P

Objective Fine needle aspiration (FNA) is a minimally invasive albeit highly effective modality used to detect solid and cystic pancreatic lesions. This manuscript aims to present our experience in diagnosing metastases to the pancreas and highlight the importance of immunocytochemistry in the diagnostic process. It also aims to provide a brief review of the literature on this topic. Methods We retrospectively searched our archives for cases of metastatic deposits to the pancreas diagnosed with FNA over a 5-year period. We also reviewed the literature for such cases. Results We describe seven cases from our archives that metastasised to the pancreas. Three of them (43%) represented metastatic renal cell carcinoma while the rest four comprised deposits from a lung adenocarcinoma, a colon adenocarcinoma, an adrenal leiomyosarcoma, and a small cell carcinoma of the urinary bladder, respectively. History of primary malignancy was available for all seven patients. All diagnoses were confirmed with the use of immunostains. In our literature review, similar to our case series, renal cell carcinoma was the most common metastasis to the pancreas managed with FNA (around one out of three patients; 35%). Of interest, our endoscopic ultrasound-FNA case of pancreatic metastasis from urinary bladder small cell carcinoma is the first reported. Conclusions As metastases to the pancreas are commonly accompanied by diverse prognostic signatures and management strategies compared to primary pancreatic malignancies, their accurate identification is imperative. Pancreatic FNA is a diagnostic modality that can confirm or exclude metastasis to the organ, especially when immunocytochemistry is applied.