The importance of risk of neoplasm as an outcome in cytologic-histologic correlation studies on thyroid fine needle aspiration.

BACKGROUND: The introduction of noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) altered the practice of thyroid pathology and reduced the risk of malignancy (ROM) associated with the indeterminate categories in the Bethesda system for reporting thyroid cytopathology (TBSRTC). It has been proposed that the evaluation of the risk of neoplasm (RON) is important in cytologic-histologic correlation studies. METHODS: A total of 5224 thyroid aspirates were performed at our institution during an 8-year period. Of the 1475 cases (28%) with surgical follow-up, the histologic diagnoses comprised benign non-neoplastic (BNN, n = 669), follicular adenoma (FA, n = 188), NIFTP (n = 42), papillary microcarcinoma (PMC) (n = 223), and malignant neoplasm excluding PMC (n = 353). The RON was calculated to include neoplasia with low risk biologic behavior (FA, NIFTP, PMC) and malignant neoplasms. In contrast, the ROM was reserved for malignant neoplasms excluding PMC. RESULTS: The RON for each TBSRTC category was: nondiagnostic (ND) 38.3%, benign 20.9%, atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS) 63.2%, follicular neoplasm or suspicious for follicular neoplasm (FN/SFN) 83.9%, suspicious for malignancy (SFM) 94%, and malignant 100%. The ROM excluding PMC was: ND 14%, benign 1.6%, AUS/FLUS 17.8%, FN/SFN 28.4%, SFM 84.4%, and malignant 99.5%. CONCLUSIONS: The RON and ROM support the recommended management guidelines from TBSRTC for all categories, except for FN/SFN. Histopathologic follow-up of FN/SFN aspirates in our study contain a very high rate of neoplasm (83.9%), which might support the management preference of conservative surgery.

Risk of malignancy and neoplasia predicted by three molecular testing platforms in indeterminate thyroid nodules on fine-needle aspiration.

BACKGROUND: The management of thyroid nodules with indeterminate cytology is challenging. Recently, molecular testing on fine-needle aspirates (FNAs) has been advocated to determine whether clinical follow-up or surgery is warranted for patients. Three different testing platforms were performed on aspirates from our institution (Afirma Thyroid FNA Analysis, RosettaGX Reveal, and Interpace ThyGenX/ThyraMIR). This study compares their diagnostic efficacy. METHODS: We conducted a retrospective analysis of indeterminate thyroid FNAs with correlating molecular testing over 4 years (2015-2018). The aspirates included diagnoses of follicular lesion of undetermined significance, follicular neoplasm, or suspicious for malignancy (SM). Based on cases that underwent surgical resection (Afirma, n = 37; Rosetta, n = 19; Interpace, n = 14), we calculated sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for risk of malignancy and neoplasia. RESULTS: The three tests performed similarly when predicting risk of malignancy. They showed high sensitivity (80-100%) and NPV (90-100%) but lower specificity (10-64%) and PPV (21-44%). When assessing their value to predict neoplasia, each test had a high PPV (76-89%) but low NPV (20-33%). The sensitivity for neoplasm was intermediate to high (50-93%), and the specificity remained extremely variable (11-67%). CONCLUSION: Overall, these molecular platforms performed similarly, displaying high NPV but low to intermediate PPV for malignancy and low NPV but high PPV for neoplasm. The risk of neoplasm is a good index for surgery, and we argue that many of the neoplasms are low-risk tumors. We endorse conservative treatment with lobectomy for cases that are indeterminate at FNA but suspicious by molecular testing.

Utilization of direct smears of thyroid fine-needle aspirates for ancillary molecular testing: A comparison of two proprietary testing platforms.

BACKGROUND: Ancillary molecular testing has been recommended for thyroid fine-needle aspirates (FNA) with indeterminate cytologic diagnoses. Rosetta Genomics and Interpace Diagnostics have developed assays that can utilize direct smears as the testing substrate. METHODS: A retrospective study of indeterminate thyroid FNAs with known histologic follow-up was performed. One Diff-Quik-stained smear and one Papanicolaou-stained smear with similar cellularity (at least 60-100 lesional cells) from each case were sent to Rosetta and Interpace, respectively, for analysis. The results were directly compared and correlated with the final histopathology. Neither company was aware of the follow-up histologic findings in these cases. RESULTS: A total of 10 thyroid FNAs were identified from our 2015 files. The cytologic diagnoses included follicular lesion of undetermined significance (FLUS, n = 5), follicular neoplasm/suspicious for follicular neoplasm (FN/SFN, n = 4), and suspicious for malignancy (SM, n = 1). Of the seven cases with benign histology, six smears were classified as benign by the RosettaGX microRNA classifier, and one case was designated as suspicious. Five cases were negative by both ThyGenX oncogene panel and ThyraMIR microRNA classifier. One case was negative by ThyGenX and positive on follow-up ThyraMIR, and one case was positive for KRAS mutation and positive on ThyraMIR. Both the RosettaGX and ThyGenX/ThyraMIR tests demonstrated positive results for the three histologically malignant cases. CONCLUSION: This study demonstrates that two molecular testing platforms performed equally well using our stained direct smears. Both molecular tests revealed a 100% negative predictive rate. RosettaGX showed a 75% positive predictive value in comparison to 60% for ThyGenX/ThyraMIR.

Fine-needle aspirates of thyroid microcarcinoma.

INTRODUCTION: Widespread use of ultrasound allows for detection of smaller thyroid nodules and preoperative evaluation with fine-needle aspiration (FNA). Both incidental and non-incidental microcarcinoma can be found, leading to uncertainty with clinical management. MATERIALS AND METHODS: A retrospective analysis of thyroid FNAs performed at our institution was conducted for the 5-year period from 2010 to 2014. Aspirates were categorized using the Bethesda System for Reporting Thyroid Cytopathology. Cytologic diagnoses were then correlated with final histopathology. Among samples with malignancy on surgical resection, nodules were stratified by size. RESULTS: A total of 2531 thyroid FNAs were identified; 587 samples had histologic correlation, and 259 malignancies were reported. They were separated into nodules >1 cm (n = 144, 56%) and ≤1 cm (n = 115, 44%). Microcarcinoma was further subdivided into incidental (size ≤0.5 cm, n = 55, 48%) and non-incidental (size >0.5 cm and ≤1 cm, n = 60, 52%). The preoperative cytologic diagnoses for incidental microcarcinoma were: benign (B, n = 11, 20%), follicular lesion of undetermined significance (FLUS, n = 15, 27%), follicular neoplasm (FN, n = 11, 20%), suspicious for malignancy (SM, n = 7, 13%), malignant (M, n = 8, 15%), and nondiagnostic (ND, n = 3, 5%). The FNA categories for non-incidental microcarcinoma were: B (n = 13, 22%), FLUS (n = 3, 5%), FN (n = 3, 5%), SM (n = 10, 17%), M (n = 29, 48%), and ND (n = 2, 3%). CONCLUSIONS: Incidental microcarcinoma is not an uncommon entity, making up 21% (55 of 259) of malignant nodules on thyroidectomy. Indeterminate diagnoses (FLUS + FN + SM) accounted for the majority (60%) of preoperative FNAs for incidental microcarcinoma, compared with 27% for those of non-incidental microcarcinoma (P < 0.05, χ2 test).

Histologic and clinical follow-up of thyroid fine-needle aspirates in pediatric patients.

BACKGROUND: Although fine-needle aspiration (FNA) has an important role in evaluating thyroid nodules in adults, there is little published information regarding its utility in the pediatric population. METHODS: A retrospective analysis of thyroid FNAs for patients who were 18 years old or younger at 2 institutions was conducted. Aspirates were retrospectively categorized with the Bethesda System for Reporting Thyroid Cytopathology. These diagnoses were then correlated with either final histopathology or clinical follow-up. RESULTS: A total of 186 thyroid FNA samples from 154 patients (122 females and 32 males), who ranged in age from 9 months to 18 years (median, 16 years; mean, 14 years), were identified. FNA was performed to evaluate 1 to 3 nodules for each patient. Aspirates were classified as follows: nondiagnostic (n = 27), benign (n = 114), atypia of undetermined significance (AUS; n = 21), follicular neoplasm (FN; n = 8), suspicious for malignancy (n = 3), and malignant (n = 13). Sixty-one samples had a histologic correlation, 68 were followed clinically for ≥2 years, and 57 either had no follow-up or were followed for <2 years. For statistical purposes, FNA diagnoses of suspicious and malignant were considered positive, and benign lesions were considered negative. The accuracy was 99%, and the sensitivity and specificity were 94% and 100%, respectively. The risk of malignancy, not including papillary microcarcinoma, was 2% for benign aspirates, 21% for AUS, 57% for FN, and 100% for suspicious or malignant aspirates. CONCLUSIONS: This analysis demonstrates that FNA is a sensitive and highly specific modality for evaluating thyroid nodules in pediatric patients. Each diagnostic category can facilitate communication and guide appropriate management. Cancer Cytopathol 2016;124:467-71. © 2016 American Cancer Society.