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The Risk of Malignancy of Thyroid Fine Needle Aspiration Cytology is Impacted by Papillary Thyroid Microcarcinoma and Non-invasive Follicular Thyroid Neoplasm with Papillary-like Nuclear Features
Abstracts Materials and Methods: All surgical pathology reports from January 2011 to January 2016 were reviewed, with cases meeting criteria for NIFTP reclassified as such. Cases with available cytology were evaluated for 18 features by two cytopathologists independently, with discrepancies reviewed by a third. The scores were compared using Chi square test. Results: 276 PTC were identified; 35 (12.7%) were NIFTP, 48 (17.4%) were IFVPC, and 193 (69.9%) were cPTC. Cytology slides were available for 6 NIFTPs; 9 IFVPC and 11 cPTC were randomly selected for comparison. The original cytologic diagnosis is shown in Table 1. NIFTP was distinguished from cPTC by absence of architectural features in all 6 cases (papillae (pZ0.001), caps (pZ0.001), irregular branching sheets (p<0.001), swirling sheets (pZ0.025), linear arrangement of cells (pZ0.049), and absence of follicular architecture (p<0.001)), as well as by absence of pseudoinclusions (p<0.001) and multinucleated giant cells (pZ0.027). Nuclear pseudoinclusions (pZ0.001), marginal micronucleoli (pZ0.018), irregular branching sheets (pZ0.025) and linear arrangement (pZ0.025) favored IFVPTC over NIFTP. Conclusions: NIFTP were originally assigned a spectrum of diagnostic categories, and rarely diagnosed as malignant, due to absence of architectural features, and less well-developed nuclear features, of cPTC. Given the potential for overtreatment of NIFTP diagnosed cytologically as PTC, revised criteria for diagnosis may be appropriate. Although further study is necessary, these findings support restricting the definitive diagnosis of PTC to cases with at least some architectural features of PTC and/or intranuclear pseudoinclusions.
PST160 The Risk of Malignancy of Thyroid Fine Needle Aspiration Cytology is Impacted by Papillary Thyroid Microcarcinoma and Non-invasive Follicular Thyroid Neoplasm with Papillary-like Nuclear Features Kristin La Fortune, Kristen Partyka, MD, Steve Jovonovich, MD, Ashley Ibrahim, MD, Xiaoyan Wang, MD, Shaoxiong Chen, MD,
S73 Harvey Cramer, MD, Chi-Shun Yang, MD, Howard Wu, MD. Indiana University School of Medicine, Indianapolis, IN Introduction: We calculated how the risk of malignancy (RM) of thyroid aspirates is impacted when papillary thyroid microcarcinomas (PMCs) measuring 1.0 cm and 0.5 cm and non-invasive follicular thyroid neoplasms with papillary-like nuclear features (NIFTPs) are excluded as malignancies. Materials and Methods: We applied The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) to 2,531 thyroid FNAs during a fiveyear period (2010-2014). The cytologic diagnoses included benign (B, nZ1851, 73%), atypia of undetermined significance (AUS, nZ231, 9%), follicular neoplasm (FN, nZ117, 5%), suspicious for malignancy (SM, nZ47, 2%), malignant (M, nZ196, 8%), and non-diagnostic (ND, nZ89, 4%). We calculated the RM for each diagnostic category based on 581 cases with histologic follow-up. The risk of neoplasm (RN) was also calculated for each TBSRTC diagnostic category, which included all malignancies, regardless of size, and follicular adenomas (FA). Results: The RN and RM for each TBSRTC diagnostic category along with the histologic diagnosis are reported in Table 1. The RM for each category including all PMCs and excluding PMCs measuring 1.0 cm and 0.5 cm is reported in Table 2. A direct comparison of the RM including PMCs and NIFTPs and excluding PMCs and NIFTPs is reported in Table 3. Our RM for benign FNAs is 13%, which decreases to 8% if PMCs measuring 0.5 cm are excluded and to 1.4% if PMCs measuring 1.0 cm are excluded. Of the 27 false-negative diagnoses, 24 cases were PMCs measuring 1.0 cm and 2 cases were NIFTPs. Conclusion: If all PMCs and NIFTPs are included, our RM for each category is 13% (B), 34% (AUS), 35% (FN), 92% (SM), 100% (M), and 35% (ND). The RM changes to 0.5% (B), 10% (AUS), 9% (FN), 46% (SM), 71% (M), and 10% (ND) if all PMCs and NIFTPs are excluded.
S74
Abstracts
PST162 Cytologic Diagnoses in Thyroid Nodules Formerly Classified as Encapsulated Follicular Variant of Papillary Thyroid Carcinoma Abberly Lott Limbach, MD, Ellen Giampoli, MD. University of Rochester, Rochester, NY
PST161 Follicular Variant of Papillary Carcinoma is Difficult to Diagnose: An Oold Recurring Challenge under Routine Practice Frida Rosenblum, MD, Allison Wrenn III, CT(ASCP), Isam-Eldin Eltoum, MD. University of Alabama at Birmingham, Birminghma, AL Introduction: The follicular variant (FVPTC) is the second most common subtype of papillary thyroid carcinoma. Recently and with molecular testing, new criteria for histologic diagnosis and sub-classification of FVPTC have been suggested. In spite of previously described cytologic features, an accurate diagnosis remains unattainable. The objective of this study is to assess the accuracy of cytologic diagnosis of FVPTC compared to other variants (OVsPTC, predominantly classic variant) under routine practice using The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC). Materials and Methods: We searched our information system for all cases of FVPTC diagnosed on surgical specimen and correlated them with prior cytologic diagnoses (2008-2015). For comparison, all cases of OVsPTC during the same period were retrieved. Diagnostic categories were reported using TBSRTC. Sensitivity of detection of FVPTC vs. OVsPTC was compared using Chi-Square. Results were considered significant at p<0.05. Results: In this study, a total of 5063 subjects had ultrasound-guided thyroid FNA (age range 12-98 years, 83% females); of those, 54 FVPTC and 179 OVsPTC were diagnosed on histology. “Atypical follicular lesion (FLUS)” was the most frequent cytologic category for FVPTC, compared to “Papillary carcinoma” for OVsPTC. 5 cases (9%) of FVPTC were diagnosed as papillary carcinoma and one (2%) as possible FVPTC. The sensitivity (95% confidence interval) of cytologic diagnosis at FLUS and above was not significantly different for FVPTC (75%, 63%-86%) vs. OVsPTC (77%-89%), but significantly different (p<0.01) at FN and above, 25% (14%-40%) vs. 61% (54%-69%) (Table 1). Conclusions: Cytologic features of papillary carcinoma are often lacking in FVPTC to render a definitive diagnosis under routine practice as reflected in the low sensitivity of these features. However, there is often enough atypia that the sensitivity of cytology for the diagnosis of FVPTC at FLUS level and above is equivalent to that of the sensitivity of OVsPTC.
Introduction: Reclassification of encapsulated follicular variant of papillary thyroid carcinoma (EFVPTC) as noninvasive follicular thyroid neoplasm with papillary-like features (NIFTP) by Nikiforov et al should decrease morbidity in patients previously diagnosed with carcinoma. These lesions have been shown to have indolent behavior and low risk of adverse outcome. Currently this is a histopathologic diagnosis made on surgical resection of part or all of the thyroid. Since thyroid nodules are initially triaged using fine needle aspiration (FNA), our study aimed to retrospectively review the histopathology of cases diagnosed as EFVPTC and then correlate prior FNA results of those cases. Materials and Methods: The LIS was searched for all thyroid resections diagnosed as EFVPTC from January 1, 2015-April 15, 2016. Surgical pathology cases were reviewed by both authors to confirm diagnoses using criteria set forth by Nikiforov. Prior FNA diagnoses were reviewed. Results: Of 545 lobectomies and thyroidectomies during the period, 27 were diagnosed as EFVPTC. Eight subsequently qualified for reclassification as NIFTP (all female, average age 45, average size of nodules 1 cm, 4 lobectomies & 4 thyroidectomies). All lobectomies went on to completion thyroidectomy. In three cases, FNAs were performed prior to surgery on nodules later diagnosed as EFVPTC. FNA diagnoses included atypia of undetermined significance (AUS) (2) and suspicious for PTC (1). One case diagnosed as AUS underwent repeat FNA with repeat AUS diagnosis before resection. All cases had changes in background thyroid necessitating resection e.g. multinodular goiter, chronic lymphocytic thyroiditis. Conclusions: Although our study is limited by small sample size, FNA can be abnormal prompting resection regardless of malignant potential of final pathology. Reclassification of EFVPTC as NIFTP suggests more conservative treatment of patients with diagnoses of AUS or or higher on FNA of smaller nodules with lobectomy. PST163 Review of the Cytological Characteristics of 21 Cases of the Follicular Variant of Papillary Thyroid Carcinoma Erik Washburn, MD, Catherine Abendroth, MD. Penn State Hershey Medical Center, Hershey, PA Introduction: Follicular variant is the most common variant of papillary thyroid carcinoma (PTC). Recent studies have shown that noninvasive encapsulated follicular variant of PTC has minimal risk of recurrence or metastasis and should be reclassified as a benign neoplasm. Considering the less aggressive nature of this entity compared to classic type PTC, accurate diagnosis is crucial to avoid overtreatment. Fine needle aspiration (FNA) is highly specific for the diagnosis of classic type PTC, however FNA diagnosis
PST160 The Risk of Malignancy of Thyroid Fine Needle Aspiration Cytology is Impacted by Papillary Thyroid Microcarcinoma and Non-invasive Follicular Thyroid Neoplasm with Papillary-like Nuclear Features Kristin La Fortune, Kristen Partyka, MD, Steve Jovonovich, MD, Ashley Ibrahim, MD, Xiaoyan Wang, MD, Shaoxiong Chen, MD,
S73 Harvey Cramer, MD, Chi-Shun Yang, MD, Howard Wu, MD. Indiana University School of Medicine, Indianapolis, IN Introduction: We calculated how the risk of malignancy (RM) of thyroid aspirates is impacted when papillary thyroid microcarcinomas (PMCs) measuring 1.0 cm and 0.5 cm and non-invasive follicular thyroid neoplasms with papillary-like nuclear features (NIFTPs) are excluded as malignancies. Materials and Methods: We applied The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) to 2,531 thyroid FNAs during a fiveyear period (2010-2014). The cytologic diagnoses included benign (B, nZ1851, 73%), atypia of undetermined significance (AUS, nZ231, 9%), follicular neoplasm (FN, nZ117, 5%), suspicious for malignancy (SM, nZ47, 2%), malignant (M, nZ196, 8%), and non-diagnostic (ND, nZ89, 4%). We calculated the RM for each diagnostic category based on 581 cases with histologic follow-up. The risk of neoplasm (RN) was also calculated for each TBSRTC diagnostic category, which included all malignancies, regardless of size, and follicular adenomas (FA). Results: The RN and RM for each TBSRTC diagnostic category along with the histologic diagnosis are reported in Table 1. The RM for each category including all PMCs and excluding PMCs measuring 1.0 cm and 0.5 cm is reported in Table 2. A direct comparison of the RM including PMCs and NIFTPs and excluding PMCs and NIFTPs is reported in Table 3. Our RM for benign FNAs is 13%, which decreases to 8% if PMCs measuring 0.5 cm are excluded and to 1.4% if PMCs measuring 1.0 cm are excluded. Of the 27 false-negative diagnoses, 24 cases were PMCs measuring 1.0 cm and 2 cases were NIFTPs. Conclusion: If all PMCs and NIFTPs are included, our RM for each category is 13% (B), 34% (AUS), 35% (FN), 92% (SM), 100% (M), and 35% (ND). The RM changes to 0.5% (B), 10% (AUS), 9% (FN), 46% (SM), 71% (M), and 10% (ND) if all PMCs and NIFTPs are excluded.
S74
Abstracts
PST162 Cytologic Diagnoses in Thyroid Nodules Formerly Classified as Encapsulated Follicular Variant of Papillary Thyroid Carcinoma Abberly Lott Limbach, MD, Ellen Giampoli, MD. University of Rochester, Rochester, NY
PST161 Follicular Variant of Papillary Carcinoma is Difficult to Diagnose: An Oold Recurring Challenge under Routine Practice Frida Rosenblum, MD, Allison Wrenn III, CT(ASCP), Isam-Eldin Eltoum, MD. University of Alabama at Birmingham, Birminghma, AL Introduction: The follicular variant (FVPTC) is the second most common subtype of papillary thyroid carcinoma. Recently and with molecular testing, new criteria for histologic diagnosis and sub-classification of FVPTC have been suggested. In spite of previously described cytologic features, an accurate diagnosis remains unattainable. The objective of this study is to assess the accuracy of cytologic diagnosis of FVPTC compared to other variants (OVsPTC, predominantly classic variant) under routine practice using The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC). Materials and Methods: We searched our information system for all cases of FVPTC diagnosed on surgical specimen and correlated them with prior cytologic diagnoses (2008-2015). For comparison, all cases of OVsPTC during the same period were retrieved. Diagnostic categories were reported using TBSRTC. Sensitivity of detection of FVPTC vs. OVsPTC was compared using Chi-Square. Results were considered significant at p<0.05. Results: In this study, a total of 5063 subjects had ultrasound-guided thyroid FNA (age range 12-98 years, 83% females); of those, 54 FVPTC and 179 OVsPTC were diagnosed on histology. “Atypical follicular lesion (FLUS)” was the most frequent cytologic category for FVPTC, compared to “Papillary carcinoma” for OVsPTC. 5 cases (9%) of FVPTC were diagnosed as papillary carcinoma and one (2%) as possible FVPTC. The sensitivity (95% confidence interval) of cytologic diagnosis at FLUS and above was not significantly different for FVPTC (75%, 63%-86%) vs. OVsPTC (77%-89%), but significantly different (p<0.01) at FN and above, 25% (14%-40%) vs. 61% (54%-69%) (Table 1). Conclusions: Cytologic features of papillary carcinoma are often lacking in FVPTC to render a definitive diagnosis under routine practice as reflected in the low sensitivity of these features. However, there is often enough atypia that the sensitivity of cytology for the diagnosis of FVPTC at FLUS level and above is equivalent to that of the sensitivity of OVsPTC.
Introduction: Reclassification of encapsulated follicular variant of papillary thyroid carcinoma (EFVPTC) as noninvasive follicular thyroid neoplasm with papillary-like features (NIFTP) by Nikiforov et al should decrease morbidity in patients previously diagnosed with carcinoma. These lesions have been shown to have indolent behavior and low risk of adverse outcome. Currently this is a histopathologic diagnosis made on surgical resection of part or all of the thyroid. Since thyroid nodules are initially triaged using fine needle aspiration (FNA), our study aimed to retrospectively review the histopathology of cases diagnosed as EFVPTC and then correlate prior FNA results of those cases. Materials and Methods: The LIS was searched for all thyroid resections diagnosed as EFVPTC from January 1, 2015-April 15, 2016. Surgical pathology cases were reviewed by both authors to confirm diagnoses using criteria set forth by Nikiforov. Prior FNA diagnoses were reviewed. Results: Of 545 lobectomies and thyroidectomies during the period, 27 were diagnosed as EFVPTC. Eight subsequently qualified for reclassification as NIFTP (all female, average age 45, average size of nodules 1 cm, 4 lobectomies & 4 thyroidectomies). All lobectomies went on to completion thyroidectomy. In three cases, FNAs were performed prior to surgery on nodules later diagnosed as EFVPTC. FNA diagnoses included atypia of undetermined significance (AUS) (2) and suspicious for PTC (1). One case diagnosed as AUS underwent repeat FNA with repeat AUS diagnosis before resection. All cases had changes in background thyroid necessitating resection e.g. multinodular goiter, chronic lymphocytic thyroiditis. Conclusions: Although our study is limited by small sample size, FNA can be abnormal prompting resection regardless of malignant potential of final pathology. Reclassification of EFVPTC as NIFTP suggests more conservative treatment of patients with diagnoses of AUS or or higher on FNA of smaller nodules with lobectomy. PST163 Review of the Cytological Characteristics of 21 Cases of the Follicular Variant of Papillary Thyroid Carcinoma Erik Washburn, MD, Catherine Abendroth, MD. Penn State Hershey Medical Center, Hershey, PA Introduction: Follicular variant is the most common variant of papillary thyroid carcinoma (PTC). Recent studies have shown that noninvasive encapsulated follicular variant of PTC has minimal risk of recurrence or metastasis and should be reclassified as a benign neoplasm. Considering the less aggressive nature of this entity compared to classic type PTC, accurate diagnosis is crucial to avoid overtreatment. Fine needle aspiration (FNA) is highly specific for the diagnosis of classic type PTC, however FNA diagnosis