Detecting Somatic Mutations for Well-Differentiated Pancreatic Neuroendocrine Tumors in Endoscopic Ultrasound-Guided Fine Needle Aspiration with Next-Generation Sequencing.

BACKGROUND: Pancreatic neuroendocrine tumors (PanNETs) exhibit heterogenous behavior, whereby some small tumors are aggressive with a propensity for metastasis. Detection of somatic mutations associated with aggressive biology may help with patient stratification and surgical decision-making in patients with well-differentiated PanNETs. Using next-generation sequencing (NGS), we investigated the feasibility of detecting somatic mutations in endoscopic ultrasound-guided, fine-needle aspiration (EUS-FNA) specimens and determining the mutational concordance between the EUS-FNA specimens and the primary tumors. METHODS: Thirty-eight patients with well-differentiated, nonfunctioning PanNETs were obtained from two tertiary referral centers. Patient demographic characteristics and tumor, clinicopathologic features were collected. Tissue from both the EUS-FNA specimen and the primary tumor was extracted from archival tissue blocks. NGS using a panel of ten genes was performed on both samples. RESULTS: In our series, the median age was 61.1 years. Tumors were predominantly left-sided (60.5%) and unifocal (94.7%). The median tumor size was 2.2 cm. NGS detected somatic mutations in 29% of primary tumors and 36.8% of EUS-FNA specimens. In primary tumors, DAXX/ATRX mutations were predominantly detected (63.6%). In EUS-FNA specimens, MEN1 mutations were predominantly detected (64.3%). Among non-wild-type specimens, mutational concordance was achieved in 31.6% of cases. In 11 patients with a detectable mutation in the primary tumor, a mutation was detected in the EUS-FNA specimen in 45.5% of cases, with a mutational concordance of 54.5%. CONCLUSIONS: NGS can detect somatic mutations in EUS-FNA specimens of well-differentiated PanNETs. Efforts to improve detection sensitivity and mutational concordance are required to overcome current technical limitations.

Polymethylmethacrylate-induced foreign body reaction presenting as bilateral parotid lesions: A case report of dermal filler adverse reaction diagnosed on fine needle aspiration.

BACKGROUND: Dermal filler injections are being increasingly used as a non-surgical option for facial cosmetic procedures. However, their use has been implicated in multiple adverse events including immediate, early onset, and late onset complications. AIM: We present a case of dermal filler-induced foreign body reaction presenting as bilateral parotid lesions and diagnosed using fine needle aspiration. CONCLUSION: This case elucidate the risk of delayed adverse events in patients with dermal filler injections and stresses the importance of awareness by patients and providers for such events.

Fine needle aspiration of bone lesions: A tertiary care centre experience.

BACKGROUND: Bone fine needle aspiration (FNA) presents several diagnostic challenges including limited sample material, reduced ability to assess the architecture, and lack of a standardised reporting system. The aim of our study is to present our experience regarding bone FNA. METHODS: We performed a 6-year retrospective search of our archives to identify all FNA cases of bone lesions. Available data regarding patients' demographics, cytopathology, and surgical pathology were recorded. The FNA cases were then grouped into five categories (atypical, neoplasm-benign, neoplasm of unknown malignant potential, suspicious for malignancy, and malignant) and the risk of malignancy (ROM) was calculated. RESULTS: A total of 341 FNA cases performed in 337 patients (M = 173, F = 164; mean age = 57.2 years) were identified. The iliac crest was the most commonly biopsied site (n = 134). The adequacy of bone FNA was 77.4%. The sensitivity and specificity regarding the nature of the lesion were 96.5% and 100%, respectively. The overall diagnostic accuracy of bone FNA was 77%. The accuracy of bone FNA for non-metastatic bone lesions including non-neoplastic lesions was 74%, while the diagnostic accuracy of bone FNA for a metastatic disease was 83.5%. The diagnostic accuracy for primary neoplastic lesions was 70%. The frequency (n,%) of cytomorphological categories were as follows: atypical (30, 8.8%); neoplasm-benign (6, 1.8%); neoplasm of unknown malignant potential (18, 5.3%); suspicious for malignancy (4, 1.2%); and malignant (145, 42.5%). The ROM in these categories was respectively as follows: 51.7%, 0%, 46.7%, 100%, and 99.1%. CONCLUSION: FNA is a sensitive and specific technique for the diagnosis of bone lesions. In most instances, an accurate diagnosis can be achieved if adequate material, ancillary studies, and radiological correlation are available.

Benign mesenchymal tumours of the tongue: A report of adult-type rhabdomyoma and granular cell tumour with a review of the literature.

The cytomorphological features of benign mesenchymal tumours of the tongue have rarely been reported. Herein, we present the cytomorphological features of adult-type rhabdomyoma, which occurred in the tongue of a female patient, and granular cell tumour (GCT), which occurred in the tongue of a male patient; both patients were in their mid-50s. The cytological features of the adult-type rhabdomyoma case included large polygonal to ovoid cells with abundant and granular cytoplasm with predominantly peripherally located, uniform, round to oval nuclei and small nucleoli. Cross-striation and crystalline intracytoplasmic structures were not seen. The cytological features of the GCT case included large cells with abundant granular pale cytoplasm, small round nuclei and small distinct nucleoli. The cytological differential diagnoses of these tumours overlap; thus, the cytological findings of the different entities included in their differential diagnoses are discussed.

Cytopathology of rare gastric mesenchymal neoplasms: A series of 25 cases and review of literature.

BACKGROUND: Gastrointestinal stromal tumour (GIST) is the most common mesenchymal neoplasm arising in the stomach. However, a number of other rare mesenchymal neoplasms do occur at this anatomic site, which often presents a diagnostic challenge for cytopathologists on endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA). Our study aims to selectively present the clinico-radiological and cytopathological characteristics of these rare "non-GIST" neoplasms, as well as their differential diagnoses. MATERIAL AND METHODS: We performed a 20 year retrospective search in the cytopathology database of our two large medical institutions for non-GIST mesenchymal neoplasms arising in the stomach and diagnosed on EUS-FNA. Data regarding the patients' demographics and radiological findings were analysed. All available cytopathology specimens were reviewed. The cytomorphological characteristics and the accompanying immunohistochemical stains, when available, were subsequently analysed. RESULTS: Twenty-five cases of gastric mesenchymal tumours were selectively included in the study after excluding all cases of GIST (n = 113) diagnosed on FNA. These cases included 10 leiomyomas (40%), eight schwannomas (32%), five glomus tumours (20%), one perivascular epithelioid cell neoplasm, and one desmoid tumour. The specimen cellularity was variable and ranged from hypocellular to highly cellular. Most smears were composed of spindle cells with a few showing epithelioid morphology. Cell blocks were available in 20 cases and a range of immunohistochemical ancillary studies were performed. DOG-1, c-KIT, smooth muscle actin (SMA), and S100-protein were the most common immunomarkers done. CONCLUSION: Our study highlights important cytomorphological characteristics of rare mesenchymal neoplasms arising in the stomach. In the appropriate clinical setting and with the help of immunohistochemistry, an accurate diagnosis of these neoplasms can be achieved.

Pancreatoblastoma in an elderly woman: A case report simulating a pancreatic neuroendocrine tumour with emphasis on cytomorphological features.

Pancreatoblastoma (PB), a rare malignant epithelial neoplasm, is the most common pancreatic neoplasm of childhood. It is exceptionally rare in the adult population and its occurrence is limited to case reports. Although the neoplastic cells of PB can have a number of different directions of differentiation, PB is defined by the combination of neoplastic cells with acinar differentiation and squamoid morules. We report a case of a female patient in her 70s who presented with elevated creatinine level, concerning a kidney disorder, and was found to have an abdominal mass on CT scan. Fine needle aspiration (FNA) showed cellular smears with numerous 3-dimentional clusters of acinar cells and scattered squamoid morules. A cell block showed sheets of cells, some of which formed acini. Numerous squamoid morules were noted and were highlighted by nuclear labelling with antibodies to B-catenin in the cell block. The FNA diagnosis was rendered as "carcinoma with acinar differentiation, favour pancreatoblastoma." Subsequent histological findings confirmed the PB diagnosis. Next generation sequencing detected a CTNNB1 mutation. Given the wide usage of FNA in the preoperative diagnosis of pancreatic masses, the cytopathologist needs to be aware of the morphological features of PB and its cytological differential diagnosis, even in an elderly patient. The differential diagnosis includes acinar cell carcinoma, pancreatic neuroendocrine tumour, and solid pseudopapillary neoplasm. In conclusion, the cytological finding of neoplastic cells with acinar differentiation combined with squamous morules and/or mesenchymal elements in the smears and more commonly in the cell blocks appears to be the most specific finding for the diagnosis of PB.

Cytopathological characteristics of solitary fibrous tumour involving the pancreas by fine needle aspiration: Making an accurate preoperative diagnosis in an uncommon location.

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.

Pathology of intraductal papillary mucinous neoplasms.

BACKGROUND: Intraductal papillary mucinous neoplasms (IPMNs) represent a unique opportunity to treat and prevent a curable neoplasm before it has the chance to progress to incurable cancer. This prospect, however, has to be balanced with the real risk of over treating patients with lesions that would, in fact, never progress during the life of the patient. PURPOSE: Informed clinical decisions in the treatment of IPMNs are first and foremost based on a deep understanding of the pathology of these lesions. CONCLUSIONS: Here we review the pathology of IPMNs, with an emphasis on the clinical relevance of the important features that characterize these lesions.

Is supplemental regional anesthesia associated with more complications and readmissions after ankle fracture surgery in the inpatient and outpatient setting?

BACKGROUND: There is concern that regional anesthesia is associated with increased risk of complications, including return to the hospital for uncontrolled pain once the regional anesthetic wears off. METHODS: Retrospective database review of patients who underwent open reduction and internal fixation of a closed ankle fracture from 2014-16 who received general anesthesia alone (GA) or general anesthesia plus regional anesthesia (RA). RESULTS: 9459 patients met inclusion criteria. Patients in the RA group had significantly longer operative duration in both inpatient (GAI=71min vs RAI=79min, p=0.002) and outpatient setting (GAO=66min vs RAI=72min, p<0.001), lower overall LOS (GA=1.7 days vs RA=1.1 days, p<0.001), and higher readmission rate for pain (RAO=4 [0.3%] vs GAO=1 [0.0%], p=0.007). CONCLUSIONS: Patients who received supplemental regional anesthesia had shorter hospital LOS, increased operative time, and increased readmission rates for rebound pain. However, the small number of patients needing readmission are not clinically significant demonstrating that regional anesthesia is safe, effective and readmission for rebound pain should not be a concern. LEVEL OF EVIDENCE: III.

TIRADS Interobserver Variability Among Indeterminate Thyroid Nodules: A Single-Institution Study.

OBJECTIVES: A high proportion of cytologically indeterminate, Afirma Gene Expression Classifier "suspicious" thyroid nodules are benign. The Thyroid Imaging Reporting and Data System (TIRADS), was proposed by the American College of Radiology in 2017 to help classify thyroid nodules based on ultrasound characteristics in a standardized fashion to guide management. We aim to determine the interobserver variability of TIRADS classification among cytologically indeterminate and Afirma suspicious nodules. METHODS: We retrospectively queried cytopathology archives for thyroid fine-needle aspiration specimens obtained between February 2012 and September 2016 with associated (1) indeterminate diagnosis, (2) ultrasound imaging at our institution, (3) Afirma suspicious result, and (4) surgery at our institution. We compared the TIRADS variability of the 3 blinded radiologists using intraclass correlation coefficients. RESULTS: Our cohort consisted of 127 nodules. Intraclass correlation coefficients can be interpreted as follows: less than 0.4, poor; 0.4 to 0.59, fair; 0.6 to 0.74, good; 0.75 to 1.00, excellent. The intraclass correlation coefficients of the raw TIRADS score and category variability was 0.561 (95% confidence interval [CI]: 0.464-0.651) or fair and 0.547 (95% CI, 0.449-0.640) or fair, respectively. When analyzing composition, echogenicity, shape, margin, and echogenic foci, the ICCs were 0.552 (95% CI, 0.454-0.643), fair; 0.533 (95% CI, 0.432-0.627), fair; 0.359 (95% CI, 0.248-0.469), poor; 0.192 (95% CI, 0.084-0.308), poor; and 0.549 (95% CI, 0.451- 0.641), fair, respectively. CONCLUSIONS: Our results show that among the subset of cytologically indeterminate and Afirma suspicious nodules, TIRADS interobserver variability was fair. Shape and margin criteria were the biggest sources of disagreement. Large prospective studies are needed to evaluate the interobserver variability of TIRADS in this subset of thyroid nodules.

Reliable Detection of Somatic Mutations in Fine Needle Aspirates of Pancreatic Cancer With Next-generation Sequencing: Implications for Surgical Management.

OBJECTIVE: To determine the feasibility of genotyping pancreatic tumors via fine needle aspirates (FNAs). BACKGROUND: FNA is a common method of diagnosis for pancreatic cancer, yet it has traditionally been considered inadequate for molecular studies due to the limited quantity of DNA derived from FNA specimens and tumor heterogeneity. METHODS: In vitro mixing studies were performed to deduce the minimum cellularity needed for genetic analysis. DNA from both simulated FNAs and clinical FNAs was sequenced. Mutational concordance was determined between simulated FNAs and that of the resected specimen. RESULTS: Limiting dilution studies indicated that mutations present at allele frequencies as low as 0.12% are detectable. Comparison of simulated FNAs and matched tumor tissue exhibited a concordance frequency of 100% for all driver genes present. In FNAs obtained from 17 patients with unresectable disease, we identified at least 1 driver gene mutation in all patients including actionable somatic mutations in ATM and MTOR. The constellation of mutations identified in these patients was different than that reported for resectable pancreatic cancers, implying a biologic basis for presentation with locally advanced pancreatic cancer. CONCLUSIONS: FNA sequencing is feasible and subsets of patients may harbor actionable mutations that could potentially impact therapy. Moreover, preoperative FNA sequencing has the potential to influence the timing of surgery relative to systemic therapy. FNA sequencing opens the door to clinical trials in which patients undergo neoadjuvant or a surgery-first approach based on their tumor genetics with the goal of utilizing cancer genomics in the clinical management of pancreatic cancer.

A histomorphologic comparison of familial and sporadic pancreatic cancers.

BACKGROUND: It is estimated that approximately 10% of pancreatic cancers have a familial component. Many inheritable genetic syndromes are associated with increased risk of pancreatic cancer, such as Peutz-Jeghers syndrome, hereditary breast-ovarian cancer and familial atypical multiple mole melanoma, but these conditions account for only a minority of familial pancreatic cancers. Previous studies have identified an increased prevalence of noninvasive precursor lesions, including pancreatic intraepithelial neoplasia, in the pancreata of patients with a strong family history of pancreatic cancer. A detailed investigation of the histopathology of invasive familial pancreatic cancer could provide insights into the mechanisms responsible for familial pancreatic cancer, as well as aid early detection and treatment strategies. METHODS: We have conducted a blinded review of the pathology of 519 familial and 651 sporadic pancreatic cancers within the National Familial Pancreas Tumor Registry. Patients with familial pancreatic cancer were defined as individuals from families in which at least a pair of first-degree relatives have been diagnosed with pancreatic cancer. RESULTS: Overall, there were no statistically significant differences in histologic subtypes between familial and sporadic pancreatic cancers (p > 0.05). In addition, among surgical resection specimens within the study cohort, no statistically significant differences in mean tumor size, location, perineural invasion, angiolymphatic invasion, lymph node metastasis and pathologic stage were identified (p > 0.05). CONCLUSIONS: Similar to sporadic pancreatic cancer, familial pancreatic cancer is morphologically and prognostically a heterogeneous disease.

Terminology and nomenclature schemes for reporting thyroid cytopathology: An overview.

The clinical management of thyroid nodules begins with a cytologic diagnosis. Current multidisciplinary approaches to thyroid nodule management rely on clear and concise diagnoses that can be reliably and reproducibly interpreted across institutions. Ultimately, this clinical necessity has led to multidisciplinary bodies throughout the world to develop standardized reporting formats which have themselves evolved over time. Herein we review the three major international nomenclatures for reporting thyroid cytopathology, including, the British Thyroid Association and Royal College of Pathologists (Thy), the Italian Consensus (TIR) and the Bethesda System for Reporting Thyroid Cytopathology. Alignment of these three diagnostic terminologies and the emergence of a single internationally agreed upon one has the potential to lead to more succinct, evidence-driven clinical management algorithms.

Impact of flow cytometry in liver cytopathology.

BACKGROUND: Fine needle aspiration (FNA) is commonly used as a diagnostic tool for the evaluation of lymphoproliferative diseases. Cytomorphology alone is often insufficient for the diagnosis and subclassification of lymphoma; therefore, flow cytometry (FC) plays an important role in the characterization of lymphoproliferative disorders. This study reviews our experience with FC on liver FNA at the Johns Hopkins Hospital. METHODS: 2,424 liver FNAs performed over a 21-year period were reviewed for clinical FC data (n=74) or a subsequent diagnosis of lymphoma in the liver without FC data (n=40). RESULTS: In our study, 114 cases (4.7%) were included out of the 2,424 liver FNAs performed during the study period. Lymphoma was diagnosed 79 times. Cytomorphology alone was diagnostic of lymphoma in 45 cases, and in 33 cases both the cytomorphology and the FC were consistent with a diagnosis of lymphoma. Neither FC nor cytomorphology were diagnostic of lymphoma on 1 specimen. In 39 cases, FC had negative results on a lesion suspicious for lymphoma based on cytomorphology. In several nonlymphoma cases, FC provided information that allowed further subclassification of the neoplasm. CONCLUSION: FC is a useful adjuvant diagnostic test for liver FNAs performed on patients with lymphoproliferative disorders.

Role of a multidisciplinary clinic in the management of patients with pancreatic cysts: a single-center cohort study.

BACKGROUND: Incidental pancreatic cysts are common, a small number of which are premalignant or malignant. Multidisciplinary care has been shown to alter management and improve outcomes in many types of cancers, but its role has not been examined in patients with pancreatic cysts. We assessed the effect of a multidisciplinary pancreatic cyst clinic (MPCC) on the diagnosis and management of patients with pancreatic cysts. METHODS: The referring institution and MPCC diagnosis and management plan were recorded. Patient were placed into one of five categories-no, low, intermediate, or high risk of malignancy within the cyst, and malignant cyst-on the basis of their diagnosis. Patients were assigned one of four management options: surveillance, surgical resection, further evaluation, or discharge with no further follow-up required. The MPCC was deemed to have altered patient care if the patient was assigned a different risk or management category after the MPCC review. RESULTS: Referring institution records were available for 262 patients (198 women; mean age 62.7 years), with data on risk category available in 138 patients and management category in 225. The most common diagnosis was branch duct intraductal papillary mucinous neoplasm. MPCC review altered the risk category in 11 (8.0%) of 138 patients. The management category was altered in 68 (30.2%) of 225 patients. Management was increased in 52 patients, including 22 patients who were recommended surgical resection. Management was decreased in 16 patients, including 10 who had their recommendation changed from surgery to surveillance. CONCLUSIONS: MPCC is helpful and alters the management over 30% of patients.

Thermo-optical characterization of fluorescent rhodamine B based temperature-sensitive nanosensors using a CMOS MEMS micro-hotplate.

A custom designed microelectromechanical systems (MEMS) micro-hotplate, capable of operating at high temperatures (up to 700 °C), was used to thermo-optically characterize fluorescent temperature-sensitive nanosensors. The nanosensors, 550 nm in diameter, are composed of temperature-sensitive rhodamine B (RhB) fluorophore which was conjugated to an inert silica sol-gel matrix. Temperature-sensitive nanosensors were dispersed and dried across the surface of the MEMS micro-hotplate, which was mounted in the slide holder of a fluorescence confocal microscope. Through electrical control of the MEMS micro-hotplate, temperature induced changes in fluorescence intensity of the nanosensors was measured over a wide temperature range. The fluorescence response of all nanosensors dispersed across the surface of the MEMS device was found to decrease in an exponential manner by 94%, when the temperature was increased from 25 °C to 145 °C. The fluorescence response of all dispersed nanosensors across the whole surface of the MEMS device and individual nanosensors, using line profile analysis, were not statistically different (p < 0.05). The MEMS device used for this study could prove to be a reliable, low cost, low power and high temperature micro-hotplate for the thermo-optical characterisation of sub-micron sized particles. The temperature-sensitive nanosensors could find potential application in the measurement of temperature in biological and micro-electrical systems.

Cytotechnologist performance for screening microfollicular atypia in indeterminate thyroid fine-needle aspirates.

INTRODUCTION: We previously identified a high level of accuracy among our cytotechnologists (CTs) for identifying nuclear atypia in thyroid fine-needle aspiration (FNA) specimens. Herewith, we present our CT performance at screening for microfollicular atypia. METHODS: 8,814 thyroid FNA specimens were identified in our archives, all screened by 1 of 11 CTs and signed out by a cytopathologist. A subsample of cases was categorized either as atypia of uncertain significance (AUS) with microfollicular proliferation (AUS-F) or suspicious for a follicular neoplasm (SFN). RESULTS: The agreement rate was low between CTs and cytopathologists for SFN and AUS-F. Only 55.8% of SFN screening diagnoses were upheld; 27.9% were downgraded to AUS, 10.4% were downgraded to benign, and 5% were upgraded. Of AUS-F screening diagnoses, 35.5% were upheld, 33.7% were downgraded to benign, and 20.2% were upgraded to SFN. Among all cases, two-step discrepancies were uncommon. CONCLUSION: Most disagreements were one-category discrepancies between AUS-F and SFN. The evaluation of microfollicular atypia is challenging given that certain follicular lesions cannot be definitively diagnosed on cytology, a high level of subjectivity is involved in the interpretation of such lesions, and the presence of nuclear or Hurthle cell atypia may complicate the diagnosis.

Extraneural metastases of primary central nervous system tumors identified by fine needle aspiration: a retrospective analysis.

OBJECTIVE: Extraneural metastasis (EM) of primary central nervous system (PCNS) neoplasms is rare and signifies a poor clinical outcome. Due to its infrequent occurrence, relatively few reports on the cytomorphology of these neoplasms have been published. We describe a series of 19 cases from 16 patients at a single, large tertiary care center. STUDY DESIGN: A retrospective analysis of 19 cases of metastases from PCNS neoplasms identified on fine needle aspiration (FNA) in 8 male and 8 female patients aged 14-72 years (mean age 39.6) from 1989 to 2013 was conducted to further characterize the cytomorphologic features identified at metastatic sites. RESULTS: Six different PCNS neoplasms were identified: meningioma, glioblastoma, hemangiopericytoma (HPC), oligodendroglioma, medulloblastoma, and retinoblastoma. The mean latency period between the diagnoses of the primary and first metastatic tumors was 7.4 years (range 0-15). The most common PCNS malignancy responsible for EM was HPC. The most common metastatic sites were the lung (31%) and soft tissue/bone (31%). CONCLUSIONS: EM of PCNS tumors is extremely rare. FNA allows for quick, safe and accurate diagnosis. Cytomorphologic features are characteristic, and in conjunction with the clinical history and immunohistochemistry, an accurate diagnosis was obtained in 100% of the cases.

Cytotechnologist performance for detecting nuclear atypia in indeterminate thyroid fine needle aspirates.

INTRODUCTION: The thyroid gland is arguably the fastest growing anatomic site for fine needle aspiration (FNA). With the increase of thyroid cases, a reevaluation of cytotechnologist screening quality metrics in terms of thyroid FNA is called for. We present our institutional cytotechnologist performance at screening for nuclear atypia by applying established quality metrics. MATERIALS AND METHODS: Information on 8,814 consecutive thyroid cytopathology cases over a 10-year period was retrieved from computerized records. A subsample of cases categorized either as atypia of uncertain significance with nuclear atypia or suspicious for malignancy with features suspicious for papillary thyroid carcinoma. The cytotechnologist and cytopathologist diagnoses were compared using step discrepancies and Δ-ratios. RESULTS: Overall discrepancy between the cytotechnologist and cytopathologist diagnoses existed in <10% of all thyroid cases. One-category discrepancies were the most common (7.8%), while two-category discrepancies were rare (0.5%). The one-category discrepancy rate correlated with cytotechnologist experience. One-category under calls were twice as common as over calls (5.3 vs. 2.5%, p < 0.0001). CONCLUSIONS: We identified a high level of quality in the screening for nuclear atypia in thyroid FNA. The one-category discrepancy rate is suited to tracking individual cytotechnologist performance, identifies outliers and appears to correlate with cytotechnologist experience.