FACTORS AFFECTING MALIGNANCY IN THYROID NODULES WITH NON-DIAGNOSTIC FINE NEEDLE ASPIRATION BIOPSY RESULT.

Introduction: Non-diagnostic (ND) fine needle aspiration biopsy (FNAB) results are problematic for clinicians who want to accurately diagnose malignancy and avoid unnecessary thyroidectomies. In this study, we aimed to investigate the incidence of malignancy in nodules whose first FNAB result was ND, and ultrasonography (USG) findings affecting malignancy and the effectiveness of repetitive biopsies. Patients and Method: In our clinic, 156 consecutive nodules whose first FNAB were ND according to the Bethesda system and underwent thyroidectomy between 1 January 2011 and 1 January 2018, directly or after repeated biopsies, were retrospectively analyzed. Results: Malignancy was detected in 44 (28%) of 156 nodules that were ND in the first FNAB. Twenty-two (31%) of 72 nodules that underwent FNAB for the second time resulted in ND again. The malignancy rate of nodules with two consecutive ND results was 23%. Of the USG features, a significant correlation was found between malignancy and solid nodule structure (p<0.001), microcalcification (p=0.025), cervical lymphadenopathy (LAP) (p=0.004) and medium-high risk USG pattern (p=0.002). In multivariate analysis, only the solid nodule structure (p<0.002) and the presence of cervical LAP (p=0.013) resulted as independent predictive factors. Conclusion: Diagnostic thyroidectomy is an effective method for reaching the diagnosis in selected patients considering the USG findings.

Deep dermal and subcutaneous canine hemangiosarcoma in the perianal area: diagnosis of perianal mass in a dog.

BACKGROUND: Tumors of the perianal area occur frequently in dogs, and the two most common tumors are perianal gland adenoma and anal sac adenocarcinoma; others such as mast cell tumor, lymphoma and melanoma can also occur at this site. Diagnostic cytology is a useful technique and is usually used to establish a definitive diagnosis of some tumors in veterinary medicine. This report describes an extremely rare case of a deep dermal and subcutaneous canine hemangiosarcoma in the perianal area. CASE PRESENTATION: A 13-year-old intact male spaniel was presented for evaluation of a 4 × 4 cm, ulcerated, and hemorrhagic mass presented in the right perianal region. In cytologic evaluation, malignant mesenchymal tumor with inflammation was diagnosed, and incidental heart worm microfilaremia was identified. Based on the cytologic evaluation, a punch biopsy (3 mm, three sites) was conducted under anesthesia and deep dermal and subcutaneous hemangiosarcoma (3 mitotic figures/10 high power field (400×)) was diagnosed by histopathological evaluation. It was also confirmed by immunohistochemistry results for cluster of differentiation 31 (CD31) and factor VIII-related antigen marker. CONCLUSIONS: Deep dermal and subcutaneous hemangiosarcoma in the perianal region is a rare condition, and its prognosis is usually poor. Perianal gland adenoma and anal sac adenocarcinoma are the two most common tumors in the perianal region, but other different types of tumors may also occur as in this case; therefore, accurate diagnosis is required using cytology and/or histopathological examination.

Development of a technical external quality assurance scheme in non-gynaecological cytology in UK.

Technical external quality assurance (EQA) schemes are well established for histopathology and cervical cytology but, to date, sadly lacking for diagnostic cytology (DC). This timely review redresses the balance by describing the development and evaluation of a technical EQA scheme for DC available to the UK, Europe and beyond.

Usefulness and Limitations of Cryopreservation for Immunocytochemical Staining of Canine Cytological Specimens for Detection of Cytokeratin and Vimentin.

Immunocytochemistry is an advanced diagnostic tool for identifying the origin of tumor cells. This study aimed to highlight the usefulness of cryopreserved, air-dried cytological samples in detecting cytokeratin and vimentin. Air-dried cytological smear samples were prepared from a total of 39 resected canine tumors and stored in a medical freezer without fixation. The duration of cryopreservation ranged from 2 to 56 months. The same tumors were processed for routine histopathological examination. Based on the morphological diagnosis, cryopreserved FNA smears from epithelial tumors were stained by enzymatic immunocytochemistry (ICC) for cytokeratin; those from mesenchymal and melanocytic tumors were stained by ICC for vimentin. To ascertain the positivity of tumor cells to the selected markers, tissue paraffin-embedded sections were also stained by immunohistochemistry (IHC) for the same markers. Immunoreactivity for cytokeratin was detected in cryopreserved cytological smears for a maximum of 46 months. Immunoreactivity for vimentin was clearly detected for 33 months. Smears stored at room temperature for 1 week did not show any signals under immunocytochemical examination. Thus, immunocytochemistry for cytokeratin and vimentin can be safely applied to air-dried smears cryopreserved in a freezer for at least 33 months.

Factors for second non-diagnostic ultrasound-guided fine-needle aspiration cytology in thyroid nodules.

INTRODUCTION: Results in fine-needle aspiration cytology (FNAC) of thyroid nodules may be non-diagnostic (ND). In these cases, it is recommended to repeat the FNAC. The aim of our study was to evaluate the influence of demographic, clinical and ultrasound (US) characteristics in the recurrence of an ND result in thyroid nodule FNAC. METHODS: A retrospective study of ND thyroid nodule FNAC was performed for the period 2017-2020. Demographic and clinical data (age, gender, cervical radiotherapy, presence of Hashimoto's thyroiditis, and TSH value) and US characteristics (nodule size, echogenicity, composition and microcalcifications) were collected at first ND FNAC. RESULTS: Out of 230 nodules with first ND FNAC (83% women; mean age 60.2±14.1 years), 195 (84.8%) underwent a second FNAC: 121 benign, 63 non-diagnostic, 9 indeterminate and 2 malignant. Nine (3.9%) underwent surgery, only 1 of which showed malignant histology and 26 (11.3%) remained under US monitoring. Demographically, patients with second ND FNAC were older (63.4±14 vs. 59±14 years; P=0.032). Females had lower risk of second ND FNAC (OR, 0.4, 0.2-0.9; P=0.016); risk of second ND FNAC was higher in patients treated with anticoagulant/antiplatelet drugs (OR, 2.2, 1.1-4.7; P=0.03). Previous cervical radiotherapy, family history of thyroid cancer, Hashimoto's thyroiditis and TSH value did not influence the risk of second ND FNAC. On US, nodule echogenicity differed significantly between the ND and diagnostic FNAC, with greater risk of an ND result in hypoechogenic nodules. Microcalcification increased the risk of ND FNAC (OR 2.2, 1.1-4.5; P=0.03). Nodule composition and size did not significantly differ according to ND or diagnostic second FNAC. CONCLUSION: Male gender, advanced age, anticoagulant/antiplatelet drug therapy, hypoechogenic nodules and microcalcified nodules are likely factors for second ND FNAC. Nodules with two ND FNACs were rarely malignant, and a more conservative approach in these cases is not unsafe.

Artificial Intelligence-Assisted Diagnostic Cytology and Genomic Testing for Hematologic Disorders.

Artificial intelligence (AI) is a rapidly evolving field of computer science that involves the development of computational programs that can mimic human intelligence. In particular, machine learning and deep learning models have enabled the identification and grouping of patterns within data, leading to the development of AI systems that have been applied in various areas of hematology, including digital pathology, alpha thalassemia patient screening, cytogenetics, immunophenotyping, and sequencing. These AI-assisted methods have shown promise in improving diagnostic accuracy and efficiency, identifying novel biomarkers, and predicting treatment outcomes. However, limitations such as limited databases, lack of validation and standardization, systematic errors, and bias prevent AI from completely replacing manual diagnosis in hematology. In addition, the processing of large amounts of patient data and personal information by AI poses potential data privacy issues, necessitating the development of regulations to evaluate AI systems and address ethical concerns in clinical AI systems. Nonetheless, with continued research and development, AI has the potential to revolutionize the field of hematology and improve patient outcomes. To fully realize this potential, however, the challenges facing AI in hematology must be addressed and overcome.

Factors Responsible for Non-Diagnostic Cytology on Ultrasound-Guided Fine-Needle Aspiration of Thyroid Nodules.

Introduction Fine-needle aspiration (FNA) is a well-recognized procedure for the diagnosis of thyroid nodules, with the advantage of being safe and inexpensive. Fine-needle aspiration cytology (FNAC) is mainly performed for nodules showing suspicious sonographic features that may require thyroidectomy. Even when FNAC is performed under sonographic guidance, the cytological specimen obtained may be inadequate, leading to a non-diagnostic outcome. The aim of this study is to determine the sonographic and technical factors influencing the outcome of FNAC. Material and methods This cross-sectional study was conducted prospectively at the radiology department, Dr. Ziauddin Hospital, Karachi, from January 1, 2019, to December 31, 2020. This study was approved by the Ethical Review Committee (ERC) of Ziauddin University. All the patients undergoing ultrasound (US)-guided FNAC of thyroid nodules were included. Patients with a history of previous thyroid surgery, very large thyroid lesions (>5 cm), and those with adjacent soft tissue pathology obscuring the assessment of thyroid nodules were excluded from this study. Result Out of 176 nodules studied, 14 were non-diagnostic and 162 were diagnostic. A 22G needle was used in most of the patients, i.e. 102 (57.3%), which demonstrated no relationship with the non-diagnostic results. According to Bethesda, 136 (77.3%) patients were benign, 22 (12.5%) had lesions with atypia/follicular lesions of undetermined significance, 14 (8%) were non-diagnostic and four (2.3%) were suspicious for malignancy. A subset, including 76 nodules, was categorized according to Thyroid Imaging Reporting and Data System (TIRADS) as follows: 28 (36.8%) nodules were moderately suspicious, 24 (31.6%) were mildly suspicious, 20 (26.3%) were not suspicious, and four (5.3%) nodules were benign. It was also observed that none of the hypoechoic nodules yielded non-diagnostic cytology. Conclusion This study concludes that radiologists must be aware of the technical details, cytologic preparation, and procedure-related complications associated with US-guided FNA to optimize patient care and the diagnostic outcome.

The "Brescia panel" (Claudin-4 and BRCA-associated protein 1) in the differential diagnosis of mesotheliomas with epithelioid features versus metastatic carcinomas.

BACKGROUND: The distinction between mesothelioma with epithelioid features and metastatic carcinoma may be challenging, particularly on cytology. A novel 2-hit Claudin-4 and BRCA-associated protein 1 (BAP1) panel was investigated. METHODS: The objective of this study was to determine the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of the panel on cytology from pleural effusions and matched biopsies, including 49 malignant mesotheliomas on cytology with 43 matched biopsies, 49 normal/reactive mesothelial proliferations, and 49 pleural metastatic carcinomas from different primaries with 21 matched pleural biopsies. The diagnostic role of the 4 categories obtained by crossing the immunostaining results was analyzed. RESULTS: Claudin-4 strongly stained all metastatic carcinomas and tested completely negative in normal mesothelium, benign reactive mesothelial hyperplasia, and malignant mesothelioma. All normal and benign mesothelial proliferations and all carcinomas except 1 were immunoreactive for BAP1, whereas BAP1 loss was observed in 88% of malignant mesotheliomas. The expression of Claudin-4 alone excluded all benign and malignant mesothelial growth, consistently characterizing all metastatic carcinomas. Double negativity was evident in all malignant mesotheliomas, and double positivity was observed in all metastatic carcinomas. BAP1-positive/Claudin-4-negative status was observed only in malignant mesotheliomas and benign mesothelial proliferations. A single metastatic anal squamous cell carcinoma had BAP1-negative/Claudin-4-positive staining. CONCLUSIONS: Claudin-4 expression was completely specific and sensitive for metastatic carcinoma, excluding mesothelial proliferations. BAP1 staining characterized 98% of metastatic carcinomas and 100% of benign mesothelial proliferations, whereas negativity was observed almost exclusively in mesotheliomas. This 2-hit panel is probably the best compromise for differentiating malignant mesothelioma and metastatic carcinoma on either cytology or biopsy specimens.

Quantitative dual isotope 123iodine/99mTc-MIBI scintigraphy: A new approach to rule out malignancy in thyroid nodules.

BACKGROUND: The aim of this study was to evaluate the role of dual isotope 123Iodine/99mTc-MIBI thyroid scintigraphy (IMS) in discriminating between malignant and benign lesions in indeterminate nodules using quantitative analysis methods. METHODS: Thirty-five consecutive patients with thyroid nodules of indeterminate or non-diagnostic cytology and cold on 123Iodine scintigraphy (10 Bethesda I, 24 Bethesda III-IV, 1 in which cytology was impossible) underwent IMS between 2017 and 2019 with uptake quantification at two time points ahead of thyroidectomy: early and late. Images were analyzed by two blinded physicians. RESULTS: Twelve nodules were malignant and 23 benign on histopathology. Mean uptake values were lower in benign than in malignant nodules at both time points: early, 8.7±4.1 versus 12.9±3.5 (P=0.005); and late, 5.3±2.7 versus 7.7±1.1 (P=0.008). Interobserver reproducibility was excellent. The intraclass correlation coefficient was 0.86 in benign and 0.92 in malignant lesions for early uptake result (ER) and 0.94 and 0.85 respectively for late uptake result (LR). The optimal LR cut-off  to exclude a diagnosis of malignancy was set at 5.9 . The sensitivity, specificity, positive predictive value, negative predictive value and accuracy of this cut-off were, respectively, 100%, 65.2%, 60%, 100% and 77.1%. CONCLUSION: Despite some study limitations, quantitative analysis of 99mTc-MIBI thyroid scintigraphy had a good reproducibility, which could help to rule out malignancy in non-diagnostic or indeterminate thyroid nodules and thereby reducing the number of patients undergoing unnecessary surgery when LR is below 5.9.

Role of Immunocytochemistry in the Cytological Diagnosis of Pulmonary Tumors.

Pulmonary cytology is a challenging diagnostic tool, and it is usually evaluated considering medical history and radiological findings in order to reach an accurate diagnosis. Since the majority of lung cancer patients have an advanced stage at diagnosis, a cytological specimen is frequently the only material available for diagnosis and further prognostic/predictive marker determination. Several types of specimens can be obtained from the respiratory system (including sputum, bronchoalveolar lavage, bronchial brushing, fine needle aspiration, and pleural fluid) with different technical preclinical management protocols and different diagnostic yields. Immunocytochemistry (ICC) has a pivotal role in the determination of diagnostic, prognostic, and predictive markers. Therefore, limited cytology samples are to be used with a cell-sparing approach, to allow both diagnostic ICC evaluation as well as predictive marker assessment by ICC or specific molecular assays. In this review, we describe the most common ICC markers used for the diagnosis and prognostic/predictive characterization of thoracic tumors in different cytological specimens.

Somatic molecular analysis augments cytologic evaluation of pancreatic cyst fluids as a diagnostic tool.

Objective: Better tools are needed for early diagnosis and classification of pancreatic cystic lesions (PCL) to trigger intervention before neoplastic precursor lesions progress to adenocarcinoma. We evaluated the capacity of molecular analysis to improve the accuracy of cytologic diagnosis for PCL with an emphasis on non-diagnostic/negative specimens. Design: In a span of 7 years, at a tertiary care hospital, 318 PCL endoscopic ultrasound-guided fine needle aspirations (EUS-FNA) were evaluated by cytologic examination and molecular analysis. Mucinous PCL were identified based on a clinical algorithm and 46 surgical resections were used to verify this approach. The mutation allele frequency (MAF) of commonly altered genes (BRAF, CDKN2A, CTNNB1, GNAS, RAS, PIK3CA, PTEN, SMAD4, TP53 and VHL) was evaluated for their ability to identify and grade mucinous PCL. Results: Cytology showed a diagnostic sensitivity of 43.5% for mucinous PCL due in part to the impact of non-diagnostic (28.8%) and negative (50.5%) specimens. Incorporating an algorithmic approach or molecular analysis markedly increased the accuracy of cytologic evaluation. Detection of mucinous PCL by molecular analysis was 93.3% based on the detection of KRAS and/or GNAS gene mutations (p = 0.0001). Additional genes provided a marginal improvement in sensitivity but were associated with cyst type (e.g. VHL) and grade (e.g. SMAD4). In the surgical cohort, molecular analysis and the proposed algorithm showed comparable sensitivity (88.9% vs. 100%). Conclusions: Incorporating somatic molecular analysis in the cytologic evaluation of EUS-FNA increases diagnostic accuracy for detection, classification and grading of PCL. This approach has the potential to improve patient management.

The use of p16/Ki-67 dual staining technology on cervical cytology of patients undergoing a LLETZ procedure.

OBJECTIVES: The main objective of this prospective observational study was to investigate the diagnostic performance of the p16/Ki-67 dual stain technique (DST) for detecting CIN 2+ in a LLETZ referral setting. Test performances were compared with HR-HPV testing and Pap cytology. METHODS: All patients referred for a LLETZ procedure were candidates for participation in this trial. A total of 110 patients were enrolled between October 2016 and March 2017. From each participant, a cervical cytology sample was obtained before the onset of the LLETZ procedure. On each sample, the dual stain technique (Roche CINtec PLUS ® test), Pap cytology and an HPV DNA assay (identifying 17 different HPV types) were performed. RESULTS: The overall disease prevalence of CIN 2+ was 56%. The mean age was 41 years, with 38% of patients being younger than 35 years. The overall sensitivity and specificity of the dual stain technique for detecting CIN 2+ was 94% (95% CI: 84.30-98.21%) and 58% (95% CI: 43.21-72.93%) respectively with a PPV of 74% (95% CI: 67.34-80.31%) and a NPV of 88% (95% CI: 72.48-94.90%). HR-HPV testing results in a similar sensitivity of 92% (95% CI: 82.17-97.33%) but considerable lower specificity of 21% (95% CI: 11.17-33.35%) compared to the dual stain technique. At an ASCUS or worse threshold, Pap cytology had the lowest sensitivity of 89% (95% CI 78.11-95.34%) compared to dual staining and HR-HPV testing. Specificity was better (48% with 95% CI of 33.29-62.81%) than that of HR-HPV testing but not as good as the DST. CONCLUSION: p16/Ki-67 dual staining provides high sensitivity and improved specificity compared to HR-HPV testing and Pap cytology for detecting CIN 2+, making it an interesting tool for identifying relevant disease in patients referred for a LLETZ procedure.

HPV negative cervical cancers and primary HPV screening.

More than 25 years ago it was established that a HPV (Human Papilloma Virus) infection was the causal factor for cervical cancer. Based on this discovery HPV vaccines were developed and primary HPV screening proposed. The impact of 10 years prophylactic HPV vaccination with the bivalent and quadrivalent vaccines has been tremendous. There is a reduction of HPV infections 16/18, 31, 33 and 45 of respectively 89%, 94%, 79% and 83%. High grade lesions have been reduced by 85% and warts by 90%. Within 20 to 30 years a reduction in cervical cancer incidence, by 70-80%, is to be expected. The 9 valent HPV vaccine, which was introduced last year and is reimbursed for girls between 12 - 19 years, is expected to increase the figures by 14 to 18%. Recently, doubt has been created regarding primary HPV screening. Since 2017, the annual screening report in Belgium suggests that 15% of the cervical cancers were HPV negative. Previous published data in Belgium (period 2001 - 2008) showed that the number of HPV negative tumors is less than half of the suggested figure (7%). Frequent reasons for false negative HPV tumors are the used HPV testing methods and the misclassification of endometrial cancers or metastasis as cervical cancers. Other explanations are the loss of HPV expression and the existence of cervical cancers independent of HPV. The incidence of HPV negative tumors doesn't give any information about the performance of primary HPV screening. Data from randomized controlled trials are very clear: if a woman has a normal cytology and no HPV infection or normal cytology and a HPV infection, then her chance of developing a CIN3 + lesion after 5 years is, respectively, 0,2% and 6%. In Belgium, primary HPV screening with dual-stain cytology triage would considerably reduce the incidence (36%) and mortality (40%) of cervical cancer. There is necessity to improve the screening as we are entering an era of vaccinated women who will get screened. Standardized high quality HPV testing is the key stone for improvement. HPV screening preferable with triage markers is superior to cytology, despite the fact that there are HPV negative cancers. The fact that there are HPV negative cancers should not undermine all idea's regarding primary HPV screening.

Rapid immunocytochemistry for the detection of cytokeratin and vimentin: assessment of its diagnostic value in neoplastic diseases of dogs.

BACKGROUND: Immunocytochemistry (ICC) is an advanced diagnostic technique used in the field of veterinary cytology. We recently developed a rapid ICC method for the detection of cytokeratin and vimentin in dogs, which helps to determine whether tumor cells are of epithelial or nonepithelial origin. However, the diagnostic value of this rapid ICC method in neoplastic diseases of dogs has not been assessed yet. OBJECTIVES: The aim of the present study was to assess the diagnostic accuracy of rapid ICC compared to standard immunohistochemistry (IHC). METHODS: Air-dried smear samples and formalin-fixed paraffin sections were prepared from tumors excised from dogs (n = 30). Immunosignals for cytokeratin and vimentin were detected in smear samples by rapid ICC, and in paraffin sections by standard IHC. Signals in smear samples detected by rapid ICC were compared with positive staining in paraffin sections detected by standard IHC and analyzed for statistical significance (kappa statistic). RESULTS: Rapid ICC detected specific immunosignals in 25/30 cases (83.3%), and nonspecific signals were detected in 5/30 cases. Statistical analysis revealed fair agreement in epithelial tumors (n = 16) with cytokeratin (κ = 0.236) and vimentin (κ = 0.294). In nonepithelial tumors (n = 14), almost perfect agreement was demonstrated with cytokeratin (κ = 0.857) and vimentin (κ = 0.857). CONCLUSIONS: The rapid ICC method can be a useful tool for the diagnostic cytology of neoplastic tissues in dogs.

The impact on women's health and the cervical cancer screening budget of primary HPV screening with dual-stain cytology triage in Belgium.

Dual stain cytology, or "diagnostic cytology", offers a significant increase in sensitivity compared to cytology, with a slight decrease in specificity. This can reduce additional investigations like colposcopies, biopsies, and follow-up visits. Cervical cancer screening for women between 25 and 65 years of age with diagnostic cytology is estimated to reduce the incidence of cervical cancer by 36% and reduce annual cervical cancer mortalities by 40%. The reduced number of screening visits and the decrease in incidence and mortality will improve quality of life. In this article, a model was created to evaluate the cost-effectiveness of diagnostic cytology for Belgium. In this approach, precancerous cells are more likely to be immediately identified during the first screening visit. This reduces both the number and frequency of follow-up visits required. After two cycles (6 years), the prevalence of CIN and cervical cancer is decreased significantly in the screened population. At a population level, these shifts can reduce the screening budget by 21%, resulting in savings of 5.3 million euro a year in Belgium. Diagnostic cytology benefits all stakeholders involved in cervical cancer screening.

Diagnostic performance of dual-staining cytology for cervical cancer screening: A systematic literature review.

Cervical cancer screening saves lives. Secondary prevention in cervical cancer screening relies on the results of primary cytology and/or HPV testing. However, primary screening with cytology has a low sensitivity, and HPV screening has a low specificity. This means that either cancers are missed, or women are over-treated. To improve performance outcomes, the concept of dual-stain cytology (CINtec® PLUS Cytology test) has been introduced. In this approach, additional staining with p16/Ki-67 is performed in cases where cytology results are abnormal (LSIL or ASCUS) and/or HPV-positive. Another way to describe this approach might be "diagnostic" cytology. In order to assess the value of this "diagnostic cytology", a systematic literature review was conducted of dual-stain cytology performance across multiple studies until May 2016. In a Belgian screening population (women age 25-65 years), dual-stain cytology was significantly more sensitive (66%) and slightly less specific (-1.0%) than cytology. In the population referred to colposcopy or with abnormal cytology (ASCUS, LSIL), dual-staining showed a significantly higher increase in specificity, and a slightly lower sensitivity than HPV testing. Specificity gains resulted in fewer false positives and an increase in the number of correct referrals to colposcopy. Dual-staining with p16/Ki-67 cytology is an attractive biomarker approach for triage in cervical cancer screening.

Thyroid Imaging Reporting and Data System and Ultrasound Elastography: Diagnostic Accuracy as a Tool in Recommending Repeat Fine-Needle Aspiration for Solid Thyroid Nodules with Non-Diagnostic Fine-Needle Aspiration Cytology.

The Thyroid Imaging Reporting and Data System (TIRADS) has been found to be accurate in the stratification of malignancy risk, and elastography has been found to have a high negative predictive value in non-diagnostic thyroid nodules. Through assessment of 104 solid non-diagnostic thyroid nodules, this study investigated the role of both in recommending repeat ultrasonography-guided fine-needle aspiration for solid thyroid nodules with non-diagnostic cytology. All nodules were classified by TIRADS (categories 4a, 4b, 4c and 5), and elastography scores were assigned according to the Rago and Asteria criteria. The malignancy risks for TIRADS categories 4a, 4b, 4c and 5 were 12.5%, 25.0%, 25.8% and 16.7%, respectively. Elastography revealed the highest diagnostic performance for TIRADS category 4a, with a sensitivity, specificity, negative predictive value, positive predictive value and accuracy of 100%, 85.7%, 100%, 50% and 87.5% for the Asteria criteria. Observation may be considered for non-diagnostic solid nodules that have no other suspicious ultrasonographic features and are also benign on real-time strain elastography using the Asteria criteria.