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Background Cytology specimens are often used for biomarker testing in the setting of neoplasia. On occasion, formalin-fixed paraffin-embedded (FFPE) cell blocks unfortunately may not yield sufficient material for testing. Recent studies have suggested that residual supernatant fluid from cell block preparation is a valuable source of DNA: both cellular and cell-free DNA (cfDNA). In the present study, the use of cfDNA from supernatant is compared against DNA from FFPE materials. Methods cfDNA was extracted prospectively from residual supernatants of 30 cytology samples (29 neoplastic cases and 1 benign ascitic fluid from a patient with a history of melanoma). Samples were tested using clinically validated next-generation-sequencing platforms and the results were compared with data from paired FFPE cell blocks in a real-time prospective clinical setting. Thirteen samples were tested on an amplicon-based assay (Solid Tumor Hotspot), and 17 samples were tested using a comprehensive capture-based assay (UW-Oncoplex). Results Neoplastic content was estimated by mutational variant allele fraction, with a mean content of 24.0% and 25.8% in supernatant and FFPE, respectively. The variant concordance between paired samples was 90%, and identical results were detected in both supernatant and FFPE samples in 74% of cases. Conclusions This study confirmed that cfDNA from supernatant is a viable alternative to FFPE cell blocks for molecular biomarker testing using both amplicon-based and capture-based assays with potential for decreasing additional tissue sampling and faster turnaround time.

The 2019 ASCCP Risk Based Management Consensus Guidelines for prevention of cervical cancer promote clinical management recommendations aligned with our increased understanding of HPV biology and cervical carcinogenesis. They employ HPV-based testing as the basis for risk estimation, allow for personalized risk-based management by incorporating knowledge of current results with prior results, and streamline incorporation of new test methods as they are validated. They continue to support the principles of "equal management for equal risk" and "balancing harms and benefits" adopted in the 2012 version of the guidelines. These updated guidelines will be able to adjust for decreasing CIN3+ risks as more patients who received HPV vaccination reach screening age. Pathology organizations were closely involved in the development of these guidelines. Herein the pathologists who served as representatives to the 2019 ASCCP guidelines steering committee and workgroups, summarize the changes that are relevant to laboratories, pathologists, and cytotechnologists. Prior relevant screening and reporting recommendations that have not been widely and/or inconsistently adopted by laboratories are also discussed and considerations for modification of laboratory practices offered.

The Bethesda System for reporting thyroid cytopathology (BSRTC) predicts an incidence of malignancy of less than 5% in thyroid nodules with a benign diagnosis on fine-needle aspiration (FNA). However, recent series have suggested that the true rate of malignancy might be significantly higher in this category of patients. We reviewed our experience by performing a retrospective analysis of patients with benign thyroid FNA results who underwent thyroidectomy between 2008 and 2013 at a large academic center. Information including demographics, ultrasound features, FNA diagnosis, and surgical follow-up information were recorded. Slides were reviewed on cytology-histology discrepant cases, and it was determined whether the discrepancy was due to sampling or interpretation error. A total of 802 FNA cases with a benign diagnosis and surgical follow-up were identified. FNA diagnoses included 738 cases of benign goiter and 64 cases of lymphocytic thyroiditis. On subsequent surgical resection, 144 cases were found to be neoplastic, including 117 malignant cases. False negative, defined as interpretation error and inadequate biopsy of the nodule harboring malignancy, was 6%. When cases of noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) were excluded from the analysis, false-negative rate was 5%. When microPTC cases were excluded, false-negative rate was 3% and was slightly less than 3% when both microPTC and NIFTP cases were excluded from the analysis. Retrospective review of neoplastic cases showed that 57% were due to sampling error and 43% were due to interpretation error. Interpretation error was more likely to occur in follicular patterned neoplasms (75%), while sampling error was more common in non-follicular variants of papillary thyroid carcinoma (non-FVPTC) (61%). With the exclusion of microPTC, interpretation errors were still more likely to occur in follicular neoplasms (79%) but there was no significant difference in sampling error between non-FVPTC (37%) and follicular patterned neoplasms (42%). Tumor size was larger in cases with interpretation error (mean = 2.3 cm) compared to cases with sampling error (mean = 1.4 cm). This study shows that the false-negative rate of thyroid FNA at our institution is not significantly above the rate suggested by the BSRTC. Interpretation errors were more likely to occur in follicular patterned neoplasms, while non-FVPTC was more frequently found in false negative cases due to inadequate sampling.

Laboratory management should be an integral part of training in pathology residency and fellowships. Herein, we have outlined some basic laboratory management topics a graduating cytopathology fellow should be familiar with. An overview of regulatory agencies that have oversight over laboratory testing, cytopathology laboratory accreditation, pre-analytic, analytic and post-analytic quality assurance, billing/coding, basic statistics, verification/validation of testing, physician credentialing, board certification/maintenance of certification, and malpractice in cytopathology are addressed. This review is by no means all inclusive, but rather a guide to the basic management related topics to be covered during cytopathology subspecialty training.

BACKGROUND Pancreatic neuroendocrine neoplasms with a Ki-67 labeling index greater than 20% were reclassified in 2017 by the World Health Organization into well differentiated (WD) and poorly differentiated grade 3 neuroendocrine carcinoma (NEC). The authors describe the cytologic features of grade 3 WD pancreatic neuroendocrine neoplasms compared with grade 2 neoplasms and NEC. METHODS Fine-needle aspirates from 65 pancreatic neuroendocrine neoplasms were reviewed, and their cytomorphologic features were compared across grade 2, WD grade 3, and PD small cell type (PD-S), large cell type (PD-L), and type not otherwise specified (PD-NOS) neoplasms. RESULTS The 65 aspirates consisted of 19 grade 2 neoplasms, 32 WD grade 3 neoplasms, and 14 NECs (6 PD-S, 5 PD-L, and 3 PD-NOS). The medians Ki-67 proliferation index was 11% (range, 3.2%-17%) in grade 2 neoplasms, 40% (range, 21%-89%) in WD grade 3 neoplasms, 80% (range, 63%-95%) in PD-S neoplasms, 39% (range, 25%-61%) in PD-L neoplasms, and 70% (range, 30%-80%) in PD-NOS neoplasms. Both grade 2 and WD grade 3 neoplasms were associated with plasmacytoid morphology and smooth nuclear contours, but WD grade 3 neoplasms had significant increases in abundant cytoplasm (72% vs 17%; P = .007), nuclear tangles (75% vs 42%; P = .006), and apoptosis (86% vs 58%; P = .005). Compared with NECs, WD grade 3 neoplasms had increased plasmacytoid morphology (75% vs 7%; P < .001), smooth nuclear contours (94% vs 64%; P = .02), round nuclei (59% vs 21%; P = .01), and less pleomorphism (13% vs 50%; P = .004), molding (9% vs 79%; P < .001), and necrosis (13% vs 43%; P = .003). WD grade 3 neoplasms had less pleomorphism (13% vs 50%; P = .04), less necrosis (13% vs 60%; P = .04), and more plasmacytoid morphology (75% vs 20%; P = .03) than PD-L. CONCLUSIONS The prevalence of cytologic features differs in WD grade 3 pancreatic neuroendocrine neoplasms compared with grade 2 neoplasms and NECs, and these differences assist in the recognition of this newly classified entity. Cancer Cytopathol 2018;126:326-35. © 2018 American Cancer Society.

BACKGROUND Well-differentiated (WD) and poorly differentiated (PD) pancreatic neuroendocrine neoplasms are biologically distinct entities with different therapies and prognoses. WD neoplasms with elevated proliferation (Ki-67 > 20%) have been shown to have an overlapping histology with PD neuroendocrine carcinomas. This study compared expert cytomorphologic assessments of differentiation in pancreatic neuroendocrine neoplasms in a multi-institutional study. METHODS Fine-needle aspiration specimens from pancreatic neuroendocrine neoplasms (grade 2 [G2] and grade 3 [G3] according to the 2017 World Health Organization classification; n = 72) were diagnosed independently by 3 cytopathologists as WD or PD (poorly differentiated large cell type [PD-L] or poorly differentiated small cell type [PD-S]) purely on the basis of cytomorphology. Their diagnoses were compared with a final classification supported by immunohistochemistry (retinoblastoma (RB), death domain- associated protein (DAXX), and α thalassemia/mental retardation syndrome X-linked (ATRX) protein expression), targeted mutation analysis (Memorial Sloan Kettering–Integrated Mutation Profiling of Actionable Cancer Targets), prior history of G1/G2 histology, and consensus. RESULTS The rate of agreement on differentiation was 38% (15 WD cases and 12 PD cases) for the 70 cases included (55 WD cases [n = 19 G2, n = 31 G3, and n = 5 could not be graded] and 15 PD cases [n = 6 PD-S, n = 6 PD-L, and n = 3 PD, not otherwise specified). Two cases could not be classified by the employed methods. PD carcinomas had a higher rate of agreement (10 of 15 [67%]) than WD neoplasms (15 of 55 [27%]). Round nuclei and plasmacytoid cells were associated with agreement for WD cases, whereas apoptosis and angulated nuclei were associated with disagreement. Necrosis was associated with agreement for PD cases. CONCLUSIONS A purely morphologic approach to the distinction between G2 and G3 pancreatic neuroendocrine neoplasms based on cytology can be challenging, with disagreement found among experienced cytopathologists. Cancer Cytopathol 2017. © 2017 American Cancer Society.

Objectives: Anorectal cytology (ARC) is a widely used screening tool for anal cancer in human immunodeficiency virus (HIV)–infected men who have sex with men (MSM). Its diagnostic accuracy needs to be improved, especially for high-grade squamous intraepithelial lesions (HSILs). Methods: Using 100 HIV+ MSM with biopsy-proven anal HSILs, we correlated histologic/cytologic findings. Results: Upon review, HSIL cells were present in 58 cytology samples and absent in 42. Positive samples were higher in cellularity and contained transformation zones (P

Context All Food and Drug Administration–approved methods in the United States for human papillomavirus testing including the Hybrid Capture 2 human papillomavirus assay and the Roche cobas human papillomavirus test are approved for cytology specimens collected into ThinPrep media but not for specimens collected into SurePath solution. Objective To compare the performance of the Roche cobas and Hybrid Capture 2 tests for the detection of high-risk human papillomavirus using both ThinPrep and SurePath preparations as part of a validation study. Design One thousand three hundred seventy-one liquid-based cytology samples, including 1122 SurePath and 249 ThinPrep specimens, were tested for high-risk human papillomavirus DNA using the Roche cobas human papillomavirus test and the Hybrid Capture 2 human papillomavirus assay. For cases with discrepant results, confirmatory testing was performed using Linear Array human papillomavirus testing. Results One hundred and fifty-six (11.38%) and 184 (13.42%) of the 1371 specimens tested positive for high-risk human papillomavirus DNA using the Hybrid Capture 2 human papillomavirus assay and Roche cobas human papillomavirus assay, respectively. In addition, 1289 (94.0%) of 1371 specimens demonstrated concordant high-risk human papillomavirus results with a κ value of 0.72 (95% confidence interval, 065–0.78). There was no statistically significant difference in the percentage of positive high-risk human papillomavirus results between the 2 liquid-based preparations with either assay. Discordant results between the 2 assays were noted in 82 of 1371 cases (6%). Twenty-seven of 82 cases (32.9%) were Hybrid Capture 2 positive/Roche cobas negative and 55 of 82 cases (67.1%) were Roche cobas positive/Hybrid Capture 2 negative. Two of 20 Hybrid Capture 2–positive/Roche cobas–negative cases (10%) and 26 of 37 Roche cobas–positive/Hybrid Capture 2–negative cases (70%) tested positive for high-risk human papillomavirus by Linear Array. Conclusions Both assays showed good agreement and excellent specificity with either ThinPrep or SurePath preparations. The number of discordant results was relatively small. The performance of both assays was similar for ThinPrep specimens, but the Roche cobas test demonstrated higher sensitivity with SurePath specimens.

Pancreatic neuroendocrine neoplasms with a Ki-67 labeling index greater than 20% were reclassified in 2017 by the World Health Organization into well differentiated (WD) and poorly differentiated grade 3 neuroendocrine carcinoma (NEC). The authors describe the cytologic features of grade 3 WD pancreatic neuroendocrine neoplasms compared with grade 2 neoplasms and NEC.Fine-needle aspirates from 65 pancreatic neuroendocrine neoplasms were reviewed, and their cytomorphologic features were compared across grade 2, WD grade 3, and PD small cell type (PD-S), large cell type (PD-L), and type not otherwise specified (PD-NOS) neoplasms.The 65 aspirates consisted of 19 grade 2 neoplasms, 32 WD grade 3 neoplasms, and 14 NECs (6 PD-S, 5 PD-L, and 3 PD-NOS). The medians Ki-67 proliferation index was 11% (range, 3.2%-17%) in grade 2 neoplasms, 40% (range, 21%-89%) in WD grade 3 neoplasms, 80% (range, 63%-95%) in PD-S neoplasms, 39% (range, 25%-61%) in PD-L neoplasms, and 70% (range, 30%-80%) in PD-NOS neoplasms. Both grade 2 and WD grade 3 neoplasms were associated with plasmacytoid morphology and smooth nuclear contours, but WD grade 3 neoplasms had significant increases in abundant cytoplasm (72% vs 17%; P = .007), nuclear tangles (75% vs 42%; P = .006), and apoptosis (86% vs 58%; P = .005). Compared with NECs, WD grade 3 neoplasms had increased plasmacytoid morphology (75% vs 7%; P.001), smooth nuclear contours (94% vs 64%; P = .02), round nuclei (59% vs 21%; P = .01), and less pleomorphism (13% vs 50%; P = .004), molding (9% vs 79%; P.001), and necrosis (13% vs 43%; P = .003). WD grade 3 neoplasms had less pleomorphism (13% vs 50%; P = .04), less necrosis (13% vs 60%; P = .04), and more plasmacytoid morphology (75% vs 20%; P = .03) than PD-L.The prevalence of cytologic features differs in WD grade 3 pancreatic neuroendocrine neoplasms compared with grade 2 neoplasms and NECs, and these differences assist in the recognition of this newly classified entity. Cancer Cytopathol 2018;126:326-35. © 2018 American Cancer Society.

Well-differentiated (WD) and poorly differentiated (PD) pancreatic neuroendocrine neoplasms are biologically distinct entities with different therapies and prognoses. WD neoplasms with elevated proliferation (Ki-67 20%) have been shown to have an overlapping histology with PD neuroendocrine carcinomas. This study compared expert cytomorphologic assessments of differentiation in pancreatic neuroendocrine neoplasms in a multi-institutional study.Fine-needle aspiration specimens from pancreatic neuroendocrine neoplasms (grade 2 [G2] and grade 3 [G3] according to the 2017 World Health Organization classification; n = 72) were diagnosed independently by 3 cytopathologists as WD or PD (poorly differentiated large cell type [PD-L] or poorly differentiated small cell type [PD-S]) purely on the basis of cytomorphology. Their diagnoses were compared with a final classification supported by immunohistochemistry (retinoblastoma (RB), death domain- associated protein (DAXX), and α thalassemia/mental retardation syndrome X-linked (ATRX) protein expression), targeted mutation analysis (Memorial Sloan Kettering-Integrated Mutation Profiling of Actionable Cancer Targets), prior history of G1/G2 histology, and consensus.The rate of agreement on differentiation was 38% (15 WD cases and 12 PD cases) for the 70 cases included (55 WD cases [n = 19 G2, n = 31 G3, and n = 5 could not be graded] and 15 PD cases [n = 6 PD-S, n = 6 PD-L, and n = 3 PD, not otherwise specified). Two cases could not be classified by the employed methods. PD carcinomas had a higher rate of agreement (10 of 15 [67%]) than WD neoplasms (15 of 55 [27%]). Round nuclei and plasmacytoid cells were associated with agreement for WD cases, whereas apoptosis and angulated nuclei were associated with disagreement. Necrosis was associated with agreement for PD cases.A purely morphologic approach to the distinction between G2 and G3 pancreatic neuroendocrine neoplasms based on cytology can be challenging, with disagreement found among experienced cytopathologists. Cancer Cytopathol 2018;126:44-53. © 2017 American Cancer Society.

A major reclassification occurred with the redesignation of noninvasive encapsulated follicular variant of papillary thyroid carcinoma as noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) due to its indolent nature. The aim of this study was to determine whether distinct cytomorphologic features could be identified on preoperative fine-needle aspiration (FNA) when NIFTP cases were compared with invasive follicular variant of papillary thyroid carcinoma (FVPTC) subtypes.Thyroid resection cases with the diagnosis of FVPTC from 2012 to 2016 were reclassified as NIFTP, invasive encapsulated follicular variant of papillary thyroid carcinoma (IEFVPTC), and invasive FVPTC subtypes. Corresponding FNA specimens were retrieved and retrospectively reviewed. A univariate analysis using Fisher's exact test was performed to determine any differences in the frequencies of various cytomorphologic features among NIFTP, IEFVPTC, and FVPTC cases. A multivariate analysis was performed to identify any independent salient features that would be helpful in differentiating NIFTP from its invasive counterparts.The study population consisted of 93 cases, including 51 cases of NIFTP, 21 cases of IEFVPTC, and 21 cases of infiltrative FVPTC. Demographics such as age, sex, and tumor size were comparable across the 3 groups. A predominantly microfollicular pattern, an absence of nuclear pseudo-inclusions, and less frequent nuclear elongations and grooves were significantly more likely to be associated with NIFTP versus its invasive counterparts. The absence of nuclear pseudo-inclusions and the presence of a microfollicular pattern were the only independent predictors of a NIFTP diagnosis.This study demonstrates that NIFTP cases have distinguishing cytomorphologic characteristics in comparison with invasive FVPTC cases. Therefore, a preoperative cytologic evaluation provides clues that can aid in the distinction between NIFTP and its invasive counterparts. Cancer Cytopathol 2017;125:865-75. © 2017 American Cancer Society.

Anorectal cytology (ARC) is a widely used screening tool for anal cancer in human immunodeficiency virus (HIV)-infected men who have sex with men (MSM). Its diagnostic accuracy needs to be improved, especially for high-grade squamous intraepithelial lesions (HSILs).Using 100 HIV+ MSM with biopsy-proven anal HSILs, we correlated histologic/cytologic findings.Upon review, HSIL cells were present in 58 cytology samples and absent in 42. Positive samples were higher in cellularity and contained transformation zones ( P .05). Cytology was able to predict HSILs in 36%, 48%, 68%, and 78% of patients with one, two, three, and four or more high-grade lesions. HSIL cells were identified in all cytology samples initially reported as HSILs or atypical squamous cells, cannot exclude HSIL and in 34 samples reported as low-grade squamous intraepithelial lesions or less. Notably, among this last category, 15 (44%) were keratinized-type HSILs.Our findings should improve the ARC detection rate for anal HSILs, helping to implement ARC as the primary screening tool for anal cancer.

Breast cytology, in particularly fine needle aspiration biopsy (FNAB), has been used for many years as a diagnostic tool for managing patients with breast lesions. In experienced hands, FNAB is highly sensitive and specific. Other benefits include its low cost, minimal invasiveness, and ability to provide same-day diagnosis. Despite all these benefits, FNAB has gradually been replaced by core needle biopsy (CNB) because of its high error rates when there is a lack of experienced cytopathologists, its inability to distinguish between invasive and in situ carcinoma, and most importantly, its inability to provide adequate and suitable materials for quantitative evaluation of HER2 and other prognostic markers. Other uses of breast cytology include touch preparation cytology for intraoperative evaluation of sentinel lymph nodes and surgical margins of lumpectomy specimens and for providing same-day diagnosis of CNB. In addition, breast cytology, such as ductal lavage and nipple fluid cytology, has also found applications in risk assessment for women at high risk for developing breast cancer. With the increased utilization of molecular technologies, genomic and proteomic studies have been successfully applied to breast cytologic preparations. It would not be far fetched to predict that in the very near future, the clinical application of molecular analyses will be routine ancillary testing in breast cytology, thus allowing early cancer detection, and improved tumor characterization as well as prediction of patients' outcomes and therapeutic responses.

The Papanicolaou Society of Cytopathology has developed a set of guidelines for pancreatobiliary cytology including indications for endoscopic ultrasound guided fine-needle aspiration biopsy, techniques of the endoscopic retrograde cholangiopancreatography, terminology and nomenclature of pancreatobiliary disease, ancillary testing, and postbiopsy management. All documents are based on the expertise of the authors, a review of the literature, discussions of the draft document at several national and international meetings over an 18-month period and synthesis of online comments of the draft document on the Papanicolaou Society of Cytopathology website [www.papsociety.org]. This document presents the results of these discussions regarding the use of ancillary testing in the cytological diagnosis of biliary and pancreatic lesions. This document summarizes the current state of the art for techniques in acquiring cytology specimens from the biliary tree as well as solid and cystic lesions of the pancreas.

Hurthle cell changes are frequently seen in reactive/hyperplastic conditions and can be extensive, resulting in the formation of nodules that must be distinguished from their neoplastic counterparts, Hurthle cell adenomas and Hurthle cell carcinoma. The primary goal of thyroid FNA in the management of Hurthle cell nodules is to separate those for which surgery is indicated, i.e., Hurthle cell adenomas and carcinomas, from those that can be managed conservatively, i.e., adenomatous nodules with oncocytic changes and Hashimoto’s thyroiditis. The distinction between Hurthle cell adenomas and carcinomas is not possible on cytology because of the inability of cytology to establish the presence of capsular and/or vascular invasion. Therefore, rendering a diagnosis of Hurthle cell neoplasm implies that these lesions should be excised to exclude a malignancy. The criteria for diagnosing “follicular neoplasm, Hurthle cell type,” or “suspicious for a follicular neoplasm, Hurthle cell type” are moderately to markedly cellular aspirate that consists exclusively or predominantly (>75 %) of Hurthle cells with little or no colloid and lack of background lymphocytes. The Hurthle cells can be either small with high N/C ratio (≥50 %) (small cell dysplasia) or large with at least 2× variability in nuclear size (large cell dysplasia). The differential diagnosis includes other neoplasms such as oncocytic and tall cell variants of papillary thyroid carcinoma, medullary carcinoma, parathyroid adenoma, and metastatic renal cell carcinoma.

Lymphocyte-only aspirates pose a significant diagnostic challenge in the interpretation of thyroid fine-needle aspiration specimens. Differential diagnosis includes Hashimoto thyroiditis, lymphoma, intrathyroidal lymph node, intrathyroidal thymoma, and thyroglossal duct cyst. Hashimoto thyroiditis especially in the florid lymphoid phase usually presents as lymphocyte-only aspirates. During this phase, numerous hyperplastic lymphoid follicles are seen throughout the gland, and they often replace the thyroid parenchyma. Lymphomas of the thyroid typically occur in older patients, almost always arise in a background of Hashimoto thyroiditis and are of B-cell lineage. Primary lymphomas of the thyroid gland are mainly diffuse large B-cell lymphoma (DLBCL) and extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) and to a much lesser extent Hodgkin and small lymphocytic lymphoma. Given the limitations of establishing a lymphoma diagnosis with only cytomorphology, morphological evaluation is commonly augmented with flow cytometry or immunohistochemistry in the diagnostic workup of lymphocyte-only fine-needle aspirates from the thyroid.

Involvement of cervical lymph nodes by metastatic disease is reported in 20–50 % of patients with well-differentiated thyroid cancer. Fine-needle aspiration biopsy (FNA) is usually required to confirm or rule out metastasis because reactive lymphadenopathy is common in the neck region. Because of a small but substantial percentage of false-negative cases, thyroglobulin (Tg) assay of aspirate from cervical lymph nodes has been advocated to supplement FNA of suspicious lymph node in patients with proven or suspected differentiated thyroid cancer. A high sensitivity (95 %) and specificity (95 %) in the detection of nodal metastases from differentiated thyroid carcinoma have been reported with Tg assay. However, Tg assay of FNA should not replace cytologic evaluation because of the potential of both false-positive and negative results. In addition, standardization in terms of sample collection and analysis is still lacking.

Numerous histiocytes can be seen in a variety of hyperplastic and neoplastic benign and malignant thyroid nodules undergoing cystic degeneration. Typically, such cystic degeneration is seen on smears of fine needle aspiration as numerous foamy macrophages, hemosiderin-laden macrophages, and scant colloid. Thyroid cysts are mostly benign. However, cysts are well-known causes of false-negative results. Risk factors for malignancy include large cysts, recurrent cysts, cysts in young males, and history of radiation. If macrophages only are present on a smear, other causes of cystic neck mass should be excluded.

Total thyroidectomy followed by surveillance of the neck and thyroid bed for recurrent disease is the mainstay of treatment for primary differentiated thyroid cancers. Ultrasound-guided fine needle aspiration (FNA) of the thyroid bed determines if the new lesion is recurrent thyroid cancer or residual hyperplastic thyroid tissue. The features of cytologic features of malignancy are usually similar to that in the primary tumor. Direct extension from head and neck squamous cell carcinoma as well as metastasis from a distant site can mimic thyroid bed recurrence of thyroid cancer. Benign entities may include hyperplasia of residual normal thyroid, normal parathyroid gland, benign lymph nodes, and benign reparative changes such as fibrosis and suture granulomas.

Data mining is a process of pattern and relationship discovery within large sets of data. Because of the large volume of data generated in healthcare settings, it is not surprising that healthcare organizations have been interested in data mining to enhance physician practices, disease management, and resource utilization. This chapter discusses a variety of data mining techniques that have been used to develop clinical decision support systems, including decision trees, neural networks, logistic regression, nearest neighbor classifiers. In addition, genetic algorithms, biologic and quantum computing, and big data analytics as well as methods of evaluating and comparing the different approaches are also discussed.

Secondary neoplasms of the thyroid gland are uncommon, but clinically they can be indistinguishable from primary thyroid tumors. The possibility of metastasis should always be considered whenever a patient presents with a thyroid nodule and they have a history of malignancy elsewhere in the body or when the cytologic picture is not consistent with or suggestive of common thyroid neoplasms. The most common primary sites of metastasis to the thyroid are kidney, lung, and breast, but the thyroid gland may also be involved by direct extension from malignancies of the head and neck region. It is important to distinguish secondary thyroid tumors from the primary tumors because patients who have metastasis to the thyroid have a poor prognosis in general, and most die shortly after the confirmation of distant metastasis. Immunohistochemistry is very helpful in the differential diagnosis.

A common pitfall in the diagnosis of thyroid nodules is the inadvertent sampling of parathyroid tissue, which may be difficult to distinguish from thyroid tissue on FNA due to similar cytologic features. Parathyroid cells are usually loosely clustered into small groups, often with a syncytial arrangement forming branching, loose, two-dimensional clusters. Microfollicular architecture is prevalent on ThinPrep preparations and this may contribute to overinterpretation of parathyroid tissue as follicular neoplasm of the thyroid. Parathyroid cells on ThinPrep preparations show round, centrally placed nuclei with stippled nuclear chromatin. The nuclei often appear smaller and darker on ThinPrep preparations than on corresponding FNA smears. The cytoplasm is scant to moderate. In addition to pathologic features, clinical features and radiologic appearance of the lesion are also helpful to differentiate between thyroid and parathyroid tissue. When the diagnosis is in doubt, parathyroid hormone immunohistochemical stain should be performed and positive PTH stain will confirm parathyroid origin.

Although architecturally, it fits into the category of follicular neoplasm, follicular variant of papillary thyroid carcinoma is classified as a subtype of papillary carcinoma because it behaves clinically like papillary carcinoma. The tumor is comprised predominantly of follicles; however, the characteristic nuclear features of classic papillary carcinoma are present. Papillary clusters are notably absent. The most common diagnostic dilemma is mistaking it for either goiter or follicular neoplasm. This is due to the fact that there is an overlapping diagnostic criteria for follicular lesions in general and also the paucity of diagnostic features of PTC in this variant, either because they are poorly developed or present only focally. When the predominant architecture is the presence of syncytial tissue fragments, especially in a background of colloid, the lesion can be misdiagnosed as nodular goiter.

Anaplastic thyroid carcinoma, although uncommon, is the most aggressive form of primary thyroid malignancy. The cellularity and the cytologic presentations of anaplastic thyroid carcinoma are variable and depend on the histologic type and the extent of tumor necrosis. Despite its diverse morphologic presentation, anaplastic thyroid carcinoma can be accurately diagnosed on FNA. False-negative diagnoses have been encountered due to low cellularity and obscuring inflammatory and necrotic debris. Its differential diagnosis includes other primary high-grade malignancies and metastases. Judicious use of immunocytochemistry may be helpful in the differential diagnosis.

Among the pediatric and adolescent population, thyroid nodules are uncommon with an incidence of 1–2 % but with a much higher risk of malignancy (14–40 %), when compared to that of adult population. Recent studies have shown that FNA, rather than diagnostic lobectomy, should be the initial diagnostic tool of choice for managing thyroid nodule in the pediatric population. Based on TBSRTC, thyroid FNA demonstrated a sensitivity and specificity of 94 % and 81 %, respectively, for evaluating thyroid nodules in the pediatric population. The majority of the malignancies encountered in the pediatric population are papillary thyroid carcinoma. Although the authors did not observe an increase in the frequency of the diagnostic category FLUS/AUS, a higher frequency of FLUS/AUS (35 %) has been reported in the literature due partly to the reluctance to diagnose malignancy in a young patient and partly to the low cellularity secondary to difficulty in sampling of these lesions. The use of molecular testing for equivocal thyroid FNA in pediatric population has not been extensively investigated.

Graves’ disease, an autoimmune disorder characterized by hyperthyroidism and a diffuse toxic goiter, is often treated by radioactive iodine 131I. Up to 35 % of patients with Graves’ disease, especially those with post 131I therapy, are found to have thyroid nodules which are often evaluated by fine-needle aspiration biopsy. Treatment with radioactive iodine can induce nuclear and cytoplasmic changes in follicular cells that could be mistaken as malignancy. The knowledge of a clinical history of Graves’ disease treated with 131I is of paramount importance in minimizing overdiagnosis of malignancy. On the other hand, patients with Graves’ disease can harbor thyroid malignancy, particularly, papillary thyroid carcinoma more than is seen in the general population. It is crucial to adhere strictly to the cytologic criteria in order to minimize over- and underdiagnosis of papillary thyroid carcinoma in patients with treated Graves’ disease.

Papillary thyroid carcinomas are the most common thyroid cancers and constitute more than 70 % of thyroid malignancies. The most common variants are the conventional type. However, many other uncommon variants have been described; the classification of these variants is based on the architectural patterns, such as follicular, solid, and cribriform-morular variants; the cell types, such as oncocytic, tall cell, and columnar cell variants; and the stromal reaction such as diffuse sclerosing, Warthin-like, and those with nodular fasciitis-like stroma. The common denominator for all the variants is the presence of nuclear features of PTC. The cytology may not be representative of the major morphologic pattern because of sampling error. In addition, a definitive cytologic diagnosis of PTC can sometimes be challenging if the typical nuclear changes of PTC were subtle or not readily apparent. It is advantageous in recognizing certain variants, namely, those with more aggressive clinical course, preoperatively since it may help the clinicians to plan for more aggressive treatment.

The 2007 National Cancer Institute State of the Science Conference proposed a category of follicular lesion of undetermined significance (FLUS) or atypia of unknown significance (AUS) for lesions that are characterized by too great a degree of architectural or cytologic atypia for definitive assignment to the benign category but insufficient findings for a diagnosis of follicular neoplasm or suspicious for carcinoma. Studies have shown that routinely subclassifying lesions in the FLUS category into two help to better stratify these cases for management, and uniform criteria have been defined for both subcategories. The first subcategory is for cases that demonstrate low cellularity as well as a predominantly microfollicular pattern and no or minimal colloid. These features elicit concern for a follicular neoplasm. The second subcategory is used for cases that show nuclear atypia, which elicit concern for a papillary carcinoma.

Hyalinizing trabecular tumor of the thyroid gland is a rare neoplasm of follicular origin that is characterized by an encapsulated nodule, a prominent trabecular growth pattern, and stromal hyalinization. This tumor typically behaves in a benign fashion but malignant cases have been reported. Hyalinizing trabecular tumors are usually well circumscribed or encapsulated with variability in color. The possibility that hyalinizing trabecular tumor represents a variant of papillary thyroid carcinoma has been considered given that the tumors frequently coexist and they share similar morphologic and nuclear features. However, on genetic analysis, hyalinizing trabecular tumor has been shown to be a discrete entity from papillary thyroid carcinoma. Hyalinizing trabecular tumors are frequently mistaken for papillary thyroid carcinoma, medullary carcinoma, or paraganglioma, but immunohistochemical stains are helpful in resolving this.

Poorly differentiated thyroid carcinoma, accounting for less than 10 % of all thyroid cancers, occupies an intermediate position between well-differentiated thyroid carcinoma and anaplastic thyroid carcinoma in regard to morphology and biologic behavior. The typical cytologic findings consist of predominantly small follicular cells with high nuclear-to-cytoplasmic ratio, marked nuclear crowding and overlapping, frequent mitotic figures, and irregular nuclei, frequently with evidence of necrosis. However, its differentiation from other thyroid neoplasms, in particular, follicular adenoma/carcinoma, and follicular variant of papillary thyroid carcinoma, may be difficult due to overlapping of cytologic features, such as microfollicular structures, irregular nuclei, and nuclear grooves. Therefore, when the cytologic findings do not permit a definitive diagnosis of poorly differentiated thyroid carcinoma, a diagnosis of “carcinoma of follicular origin” or “carcinoma not otherwise specified” should be rendered and not as “follicular variant of papillary thyroid carcinoma” and certainly not as “follicular neoplasm.”

Cystic change is commonly seen in papillary thyroid carcinoma. Macrophages can be seen in variable numbers with or without hemosiderin-laden pigments. Some cytologic features have been found to be useful in the differential diagnosis between cystic papillary thyroid carcinoma and cystic degeneration in a benign goiter. Atypical histiocytoid cells have been described in smears of cystic papillary thyroid carcinoma. These atypical histiocytoid cells have abundant vacuolated cytoplasm, nuclear pleomorphism, and nucleoli. They are larger and more atypical than benign histiocytes. The combination of macrophages, hemosiderin, cellular debris, and old blood in the background may obscure distinction between cystic papillary thyroid carcinoma and cystic goiters. Ancillary immunohistochemical markers and mutational analysis may be useful in challenging specimens.

The finding of thyroid tissue in a neck mass without distinct connections to the thyroid gland is uncommon but poses a diagnostic dilemma to the cytologist as to whether the finding represents a metastatic thyroid malignancy to the cervical node or ectopic thyroid tissue/benign thyroid inclusions in cervical lymph node. Some consider that all thyroid tissues found in the lateral cervical nodes represent nodal metastases from a primary thyroid carcinoma while others believe the existence of benign thyroid tissue inclusions in cervical lymph nodes. The finding of cytologically benign-appearing follicular cells with or without colloid does not necessarily imply a benign process since the pattern of growth of certain thyroid carcinomas can be so well differentiated as to simulate non-neoplastic thyroid tissue. On the other hand, the presence of cytologic and/or architectural atypia in follicular cells, even if accompanied by a lymphoid background, does not always indicate a metastatic thyroid carcinoma. Therefore, it is best to adopt a conservative stance with respect to a diagnosis of malignancy as long as definitive cytologic features of papillary thyroid carcinoma are not identified.

Well-differentiated thyroid cancer arising in struma ovarii is rare. The optimal management of this entity remains undefined. Unilateral cystectomy, unilateral salpingo-oophorectomy (USO), or total abdominal hysterectomy with bilateral salpingo-oophorectomy (TAH/BSO), in addition to total thyroidectomy and radioactive iodine (RAI) ablation, have been employed by various groups. We hypothesized that in patients with thyroid cancer arising within struma ovarii, pelvic surgery alone would be sufficient, provided there is no evidence of gross extra-ovarian extension.We review a series of four patients from a single institution and 53 cases from the literature, comparing the extent of treatment and outcomes. Our literature review focused on low-risk patients with struma ovarii confined to the ovary, without evidence of gross extra-ovarian spread or distant metastases. Cumulative recurrence rate was determined by using the Kaplan-Meier method.We report the treatment of four patients with well-differentiated thyroid cancer arising within struma ovarii. Patients underwent USO, BSO, or TAH/BSO. One patient underwent prophylactic total thyroidectomy in anticipation of RAI treatment, and was found to have a synchronous papillary thyroid carcinoma. All patients clinically remain without evidence of disease at a median follow-up of 9 (range 0.8-13) years. Treatment strategies in 53 cases from a review of the literature varied. The pooled cumulative recurrence rate of 57 cases with struma ovarii confined to the ovary was 7.5% at 25 years.Thyroid cancer arising in struma ovarii is rare. Controversy exists regarding the extent of pelvic resection and management of the thyroid gland. In our series of four patients, all patients are alive without evidence of disease, and the 25-year recurrence rate of 57 cases was low (7.5%), despite a variety of approaches to surgical resection and adjuvant treatment. Extensive pelvic surgery and prophylactic total thyroidectomy to facilitate RAI therapy may be reserved for patients with gross extra-ovarian extension or distant metastases.

Finkelstein A, Levy G H, Hui P, Prasad A, Virk R, Chhieng D C, Carling T, Roman S A, Sosa J A, Udelsman R, Theoharis C G & Prasad M L (2012) Histopathology 60, 1052–1059 Papillary thyroid carcinomas with and without BRAF V600E mutations are morphologically distinct Aims: The BRAF V600E mutation resulting in the production of an abnormal BRAF protein has emerged as the most frequent genetic alteration in papillary thyroid carcinomas (PTCs). This study was aimed at identifying distinctive features in tumours with and without the mutation. Methods and results: Thirty-four mutation-positive and 22 mutation-negative tumours were identified by single-strand conformation polymorphism of the amplified BRAF V600E region in the tumour DNA. Mutation-positive tumours were more common in patients older than 45 years (24/33, P = 0.05), in classic (23/30, P = 0.01), tall cell (4/5) and oncocytic/Warthin-like (2/2) variants of PTC, and in subcapsular sclerosing microcarcinomas (4/4). In contrast, all 12 follicular variants (P

Context.—Our cytology laboratory, like many others, is under pressure to improve quality and provide test results faster while decreasing costs. We sought to address these issues by introducing new technology and lean principles.Objective.—To determine the combined impact of the FocalPoint Guided Screener (GS) Imaging System (BD Diagnostics–TriPath, Burlington, North Carolina) and lean manufacturing principles on the turnaround time (TAT) and productivity of the gynecologic cytology operation.Design.—We established a baseline measure of the TAT for Papanicolaou tests. We then compared that to the performance after implementing the FocalPoint GS Imaging System and lean principles. The latter included value-stream mapping, workflow modification, and a first in–first out policy.Results.—The mean (SD) TAT for Papanicolaou tests before and after the implementation of FocalPoint GS Imaging System and lean principles was 4.38 (1.28) days and 3.20 (1.32) days, respectively. This represented a 27% improvement in the average TAT, which was statistically significant (P < .001). In addition, the productivity of staff improved 17%, as evidenced by the increase in slides screened from 8.85/h to 10.38/h. The false-negative fraction decreased from 1.4% to 0.9%, representing a 36% improvement.Conclusions.—In our laboratory, the implementation of FocalPoint GS Imaging System in conjunction with lean principles resulted in a significant decrease in the average TAT for Papanicolaou tests and a substantial increase in the productivity of cytotechnologists while maintaining the diagnostic quality of gynecologic cytology.

Context.—Mucins are glycoproteins produced by both normal and neoplastic glandular epithelial cells including endocervix. Objective.—To determine the expression of mucins in uterine cervical glandular lesions and whether mucin expression correlates with the nature and origin of the glandular lesions. Design.—Antibodies to MUC1, MUC2, MUC4, and MUC5AC were applied on 52 cases including 14 endocervical adenocarcinomas (including 4 adenosquamous carcinomas), 9 endometrial carcinomas (8 endometrioid adenocarcinomas and 1 adenosquamous carcinoma), 8 adenocarcinoma in situ (AIS), 2 glandular dysplasias, 6 tubal metaplasias, 10 microglandular hyperplasias, and 3 normal endocervix. The presence of any staining was considered positive. Results.—All benign endocervical epithelia, including tubal metaplasia and microglandular hyperplasia, expressed MUC1, MUC4, and MUC5AC but not MUC2. Almost all endocervical AIS and carcinomas and all endometrial adenocarcinomas expressed MUC1; the exceptions were 2 cases of endocervical adenocarcinoma and 1 case of adenosquamous carcinoma of the endocervix. MUC2 staining was noted in 25%, 40%, and 22% of AIS, endocervical adenocarcinomas, and endometrial adenocarcinomas, respectively. About 38% of AIS, 75% of endocervical adenocarcinomas, and 44% of endometrial adenocarcinomas expressed MUC4. Half of AIS, most of endocervical adenocarcinomas, and 22% of endometrial adenocarcinomas expressed MUC5AC. The difference in MUC4 and MUC5AC expression between benign endocervical lesions and AIS and the difference in MUC5AC expression between endocervical and endometrial neoplasms were statistically significant. Conclusions.—Mucin expressions differed among benign endocervical lesions and AIS and among endocervical and endometrial malignancies. These results suggest that mucin staining may potentially be helpful in differentiating various uterine cervical glandular lesions.

Background and study aims Masses in the spleen can be sampled by endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) but the diagnosis of lymphoma using EUS-FNA and flow cytometry has not been reported. We report our experience with transgastric EUS-FNA and flow cytometry in the investigation of patients with suspected lymphoma of the spleen. Patients and methods All patients with splenic lesions that had been detected by computed tomography and who were referred for transgastric EUS-FNA over a 3-year period were enrolled in this study. The tissue obtained by EUS-FNA was evaluated by flow cytometry in all patients. Results Six patients with splenic masses were enrolled (four men, two women; median age 58.5 years, range 41 - 82 years). The mean size of the short axis of the lesions was 37.8 mm (SD 23.76 mm) and the mean size of the long axis was 45.6 mm (SD 31.72 mm). EUS-FNA was performed successfully in all patients and the tissue obtained was evaluated by flow cytometry. Two patients were diagnosed with lymphoma; no pathology was identified in the other four patients. Lymphoma of the spleen appeared as sharply demarcated echo-poor lesions; benign lesions appeared echo-rich in comparison with the surrounding splenic tissue. The two patients who were diagnosed with lymphoma underwent chemotherapy. Of the four patients in whom no pathology was identified, one patient subsequently underwent splenectomy for evaluation of persistent abdominal pain and was diagnosed with lymphoma; the three other patients had true-negative disease on the evidence of long-term follow-up (mean 8 months; range 6 - 12 months). No complications related to the EUS-FNA procedure were encountered in any patient. Conclusions EUS-FNA of spleen masses is a safe technique that aids in the diagnosis of lymphoma when used in conjunction with flow cytometry.

The cytologic diagnosis of primary conventional renal-cell adenocarcinoma (cRCC) is usually straightforward; however, metastatic cRCC must be distinguished from a variety of neoplasms with clear-cell features. CD10, a cell membrane-associated neutral endopeptidase, and renal-cell carcinoma marker (RCCma), an antibody against human proximal tubular brush border antigen, have recently been shown to be useful in the diagnosis of cRCC. We compared CD10 and RCCma in cell block material from fine-needle aspiration biopsies (FNABs) to assess their utility in the diagnosis of metastatic cRCC, in cytologic specimens. Seven primary and sixteen metastatic cRCCs were immunostained with CD10 and RCCma. The immunoreactivity results were compared with those of a variety of neoplasms originating from other sites such as the liver, lungs, breast, and the gastrointestinal tract. The sensitivity and specificity of CD10 for cRCC were 100% and 59%, respectively. The sensitivity and specificity of RCCma for cRCC were 35% and 100%, respectively. We conclude that CD10 has limited value in confirming the diagnosis of cRCC because of its low specificity. RCCma, when positive, is highly specific for cRCC, but its low sensitivity hinders its diagnostic usefulness.

The 2007 Bethesda classification for thyroid cytology defines follicular neoplasm as a category of cases with cellular specimens demonstrating abundant follicular cells arranged in a microfollicular pattern with little or no colloid. The current recommendation for the management of these cases is diagnostic lobectomy. There has been great difficulty and variability in triaging and reporting follicular neoplasm. To increase diagnostic accuracy, at the study institution, this category is subclassified further into 3 categories: 1) microfollicular-patterned neoplasm (MN); 2) Hürthle cell neoplasm (HN); and 3) follicular lesion with some features suggestive of but not diagnostic of the follicular variant of papillary thyroid carcinoma (FL). The authors reviewed the cases of follicular neoplasm observed over a period of 5 years to document the follow-up trend using this modified classification.A search of the cytology records was performed for the period between January 2008 and December 2012. All thyroid fine-needle aspiration cases were reviewed and those with a diagnosis of follicular neoplasm (including Hürthle cell neoplasm) were identified. Correlating follow-up surgical pathology reports were reviewed.A total of 399 cases of follicular neoplasm with surgical follow-up were identified. Malignancy was identified in 32% of all cases of follicular neoplasm and was found to be disproportionately higher in the FL category (73%). A cytological diagnosis of FL is more likely to be called malignant (73%) than benign neoplastic (9%) or benign nonneoplastic (18%). A cytological diagnosis of MN or HN is more likely to be benign neoplastic (46% and 46%, respectively) than malignant (29% and 26%, respectively) or benign nonneoplastic (25% and 28%, respectively). Of the cytological features examined, 2 (nuclear enlargement and nuclear grooves) were significantly associated with the follicular variant of papillary thyroid carcinoma.The results of the current study clearly indicate that follicular lesions with even subtle nuclear atypia have a high positive predictive value for malignancy and therefore should be distinguished from other follicular lesions because these cases require more aggressive surgical management. The current study also raises an important issue concerning the current thyroid classification based on the 2007 Bethesda classification for thyroid cytology. Future thyroid fine-needle aspiration classification schemes should consider subclassifying follicular neoplasms for the purpose of risk stratification.