Active surveillance is a feasible and safe strategy in selected patients with papillary thyroid cancer and suspicious cervical lymph nodes detected after thyroidectomy.

Objective: After initial treatment, up to 30% of patients with papillary thyroid cancer (PTC) have incomplete response, mainly cervical lymph node (LN) disease. Previous studies have suggested that active surveillance (AS) is a possible option for these patients. Our aim was to report the results of AS in patients with PTC and cervical LN disease. Materials and methods: In this retrospective observational study, we included adult patients treated and followed for PTC, who presented with cervical LN disease and were managed with AS. Growth was defined as an increase ≥ 3mm in either diameter. Results: We included 32 patients: 27 (84.4%) women, age of 39 ± 14 years, all initially treated with total thyroidectomy, and 22 (69%) with therapeutic neck dissection. Cervical LN disease was diagnosed 1 year (0.3-12.6) after initial management, with a diameter of 9.0 mm (6.0-19.0). After a median AS of 4.3 years (0.6-14.1), 4 (12.5%) patients had LNgrowth: 2 (50%) of whom were surgically removed, 1 (25%) was effectively treated with radiotherapy, and 1 (25%) had a scheduled surgery. Tg increase was the only predictive factor of LN growth evaluated as both the delta Tg (p < 0.0366) and percentage of Tg change (p < 0.0140). None of the included patients died, had local complications due to LN growth or salvage therapy, or developed distant metastases during follow-up. Conclusion: In selected patients with PTC and suspicious cervical LNs diagnosed after initial treatment, AS is a feasible and safe strategy as it allows effective identification and treatment of the minority of patients who progress.

Homogentisic acid metabolism inhibits papillary thyroid carcinoma proliferation through ROS and p21-induced cell cycle arrest.

Thyroid cancer is one of the most common primary endocrine malignancies worldwide, and papillary thyroid carcinoma (PTC) is the predominant histological type observed therein. Although PTC has been studied extensively, our understanding of the altered metabolism and metabolic profile of PTC tumors is limited. We identified that the content of metabolite homogentisic acid (HGA) in PTC tissues was lower than that in adjacent non-cancerous tissues. We evaluated the potential of HGA as a novel molecular marker in the diagnosis of PTC tumors, as well as its ability to indicate the degree of malignancy. Studies have further shown that HGA contributes to reactive oxygen species (ROS) associated oxidative stress, leading to toxicity and inhibition of proliferation. In addition, HGA caused an increase in p21 expression levels in PTC cells and induced G1 arrest. Moreover, we found that the low HGA content in PTC tumors was due to the low expression levels of tyrosine aminotransferase (TAT) and p-hydroxyphenylpyruvate hydroxylase (HPD), which catalyze the conversion of tyrosine to HGA. The low expression levels of TAT and HPD are strongly associated with a higher probability of PTC tumor invasion and metastasis. Our study demonstrates that HGA could be used to diagnose PTC and provides mechanisms linking altered HGA levels to the biological behavior of PTC tumors.

Conformal thyroidectomy is a feasible option in papillary thyroid microcarcinoma: a retrospective cohort study with 10-year follow-up results.

BACKGROUND: In recent years, there has been an increasing prevalence of patients with papillary thyroid microcarcinoma (PTMC) without lymph node involvement in medical centers worldwide. For patients who are unable to undergo active surveillance (AS) and are afraid of postoperative complications, conformal thyroidectomy may be a suitable option to ensure both preservation of function and complete removal of the tumor. METHODS: The patients in the cohort during 2010 to 2015 were retrospectively enrolled strictly following the inclusion and exclusion criteria. The observation and control groups were defined based on the surgical approach, with patients in the observation group undergoing conformal thyroidectomy and patients in the control group undergoing lobectomy. Event-free survival (EFS), the interval from initial surgery to the detection of recurrent or metastatic disease, was defined as the primary observation endpoint. RESULTS: A total of 319 patients were included in the study, with 124 patients undergoing conformal thyroidectomy and 195 patients undergoing lobectomy. When compared to lobectomy, conformal thyroidectomy demonstrated reduced hospital stays, shorter operative times, and lower rates of vocal cord paralysis and hypoparathyroidism. Furthermore, the mean bleeding volume during the operation and the rate of permanent hypothyroidism were also lower in the conformal thyroidectomy group than in the lobectomy group. However, there was no statistically significant difference observed in the 5- and 10-year EFS between the two groups. CONCLUSIONS: Conformal thyroidectomy had advantages in perioperative management and short-term complication rates, with an EFS that was not inferior to that of lobectomy. Thus, conformal thyroidectomy is a feasible option for low-risk PTMC patients.

[Treatment strategy for low-risk papillary thyroid carcinoma with diameter smaller than 1 cm: immediate surgery vs active surveillance].

The incidence of differentiated thyroid cancer is increasing rapidly worldwide, with subcentimeter papillary thyroid carcinoma (SPTC) with a diameter of less than 1 cm accounting for more than 50%. Active surveillance (AS) as an alternative to immediate surgery for low-risk SPTC was launched in Japan in the 1990s and has been implemented in several countries, including Japan and the United States. However, the indications and safety of performing AS for low-risk SPTC remain controversial. In this article, the author summarizes the existing literature and explores its limitations of AS implementation, the effectiveness of surgical treatment, and the different attitudes of countries on AS, aiming to provide some references for the treatment options of low-risk SPTC.

Spatial Distribution of Macrophage and Lymphocyte Subtypes within Tumor Microenvironment to Predict Recurrence of Non-Muscle-Invasive Papillary Urothelial Carcinoma after BCG Immunotherapy.

Non-muscle-invasive papillary urothelial carcinoma (NMIPUC) of the urinary bladder is the most common type of bladder cancer. Intravesical Bacille Calmette-Guerin (BCG) immunotherapy is applied in patients with a high risk of recurrence and progression of NMIPUC to muscle-invasive disease. However, the tumor relapses in about 30% of patients despite the treatment, raising the need for better risk stratification. We explored the potential of spatial distributions of immune cell subtypes (CD20, CD11c, CD163, ICOS, and CD8) within the tumor microenvironment to predict NMIPUC recurrence following BCG immunotherapy. Based on analyses of digital whole-slide images, we assessed the densities of the immune cells in the epithelial-stromal interface zone compartments and their distribution, represented by an epithelial-stromal interface density ratio (IDR). While the densities of any cell type did not predict recurrence, a higher IDR of CD11c (HR: 0.0012, p-value = 0.0002), CD8 (HR: 0.0379, p-value = 0.005), and ICOS (HR: 0.0768, p-value = 0.0388) was associated with longer recurrence-free survival (RFS) based on the univariate Cox regression. The history of positive repeated TUR (re-TUR) (HR: 4.93, p-value = 0.0001) and T1 tumor stage (HR: 2.04, p-value = 0.0159) were associated with shorter RFS, while G3 tumor grade according to the 1973 WHO classification showed borderline significance (HR: 1.83, p-value = 0.0522). In a multivariate analysis, the two models with a concordance index exceeding 0.7 included the CD11c IDR in combination with either a history of positive re-TUR or tumor stage. We conclude that the CD11c IDR is the most informative predictor of NMIPUC recurrence after BCG immunotherapy. Our findings highlight the importance of assessment of the spatial distribution of immune cells in the tumor microenvironment.

The model for predicting the central lymph node metastasis in cN0 papillary thyroid microcarcinoma with Hashimoto's thyroiditis.

Background: The relationship between Hashimoto's thyroiditis (HT) and papillary thyroid microcarcinoma (PTMC) is controversial. These include central lymph node metastasis (CLNM), which affects the prognosis of PTMC patients. This study aimed to establish a predictive model combining ultrasonography and clinicopathological features to accurately evaluate latent CLNM in PTMC patients with HT at the clinical lymph node-negative (cN0) stage. Methods: In this study, 1102 PTMC patients who received thyroidectomy and central cervical lymph node dissection (CLND) from the First Affiliated Hospital of Shandong First Medical University from January 2021 to December 2022 and the 960th Hospital of PLA from January 2021 to December 2022 were jointly collected. The clinical differences between PTMCs with HT and those without HT were compared. A total of 373 PTMCs with HT in cN0 were randomly divided into a training cohort and a validation cohort. By analyzing and screening the risk factors of CLNM, a nomogram model was established and verified. The predictive performance was measured by the receiver operating characteristic (ROC) curve, calibration curve, and clinical decision curve analysis (DCA). Results: The ratio of central lymph node metastasis (CLNMR) in PTMCs with HT was 0.0% (0.0%, 15.0%) and 7.7% (0.0%, 40.0%) in the non-HT group (P<0.001). Multivariate logistic regression analysis showed that age, gender, calcification, adjacent to trachea or capsule, and TPOAB were predictors of CLNM in PTMCs with HT. The areas under the curve (AUC) of the prediction models in the training cohort and the validation cohort were 0.835 and 0.825, respectively, which showed good differentiation ability. DCA indicates that the prediction model also has high net benefit and clinical practical value. Conclusion: This study found that CLN involvement was significantly reduced in PTMC patients with HT, suggesting that different methods should be used to predict CLNM in PTMC patients with HT and without HT, to more accurately assist preoperative clinical evaluation. The actual CLNM situation of PTMCs with HT in cN0 can be accurately predicted by the combination of ultrasonography and clinicopathological features.

Coexistence of Hashimoto's thyroiditis and papillary thyroid carcinoma revisited in thyroidology, an experience from an endemic region: fad or future?

OBJECTIVE: Papillary thyroid carcinoma, per se, is the most common type of thyroid cancer, and Hashimoto's thyroiditis is the most frequent autoimmune disease of the papillon gland. The liaison between Hashimoto's thyroiditis and thyroid cancers is still an ongoing debate in thyroidology. The aim of the study was to discuss the frequency of the co-occurrence of Hashimoto's thyroiditis and papillary thyroid carcinoma. METHODS: This study is designed as a retrospective analytical cohort study. The institutional database and archive of histopathology scanning identified the patients who had undergone thyroidectomy between January 2022 and January 2016. The Statistical Package for Social Sciences v21.0 program was used for statistical purposes. Descriptive and chi-square tests were applied, and a p<0.05 was considered significant. RESULTS: Of 498 patients who had undergone thyroidectomy for 4 years, 99 (20%) were male and 399 (80%) were female. Of note, papillary thyroid carcinoma was revealed in 160 (32%) patients, and Hashimoto's thyroiditis was recognized in 178 (35.74%) patients. The prevalence of Hashimoto's thyroiditis in cases with papillary thyroid carcinoma was 43.8%, while the prevalence in patients with Hashimoto's thyroiditis was 41.1%. CONCLUSION: A debate still remains on the propriety of these two phenomena. Herewith, we recognized a correlation between the presence of papillary thyroid carcinoma and Hashimoto's thyroiditis. Providers should be vigilant about the coexistence of these phenomena. We might postulate the so-called total thyroidectomy for cases with a cytologic diagnosis of Hashimoto's thyroiditis with a papillary thyroid carcinoma. As a matter of fact, this issue merits further investigation.

Rare Columnar Cell Variant of Papillary Thyroid Carcinoma with Cervical Spine Metastasis: A Case Report.

BACKGROUND: Columnar cell carcinoma is a rare subtype of papillary thyroid carcinoma (CCV-PTC) that accounts for only 0.15% to 0.2% of all Papillary Thyroid Carcinomas (PTCs). It has aggressive behavior but a better prognosis than anaplastic thyroid carcinoma. CASE PRESENTATION: A 64-year-old female presented with a huge thyroid mass resulting in compressive myelopathy and was diagnosed as CCV-PTC, not anaplastic carcinoma. After multidisciplinary discussions, we decided to proceed with otolaryngological, thoracic, and orthopaedic surgery. All tumours were unresectable, and we planned to proceed with R2 resection to resolve the gait disturbance and anterior fusion to resolve spinal instability. CONCLUSION: Advanced-stage thyroid cancer is relatively uncommon, but desirable treatment effects can be expected through accurate pathological diagnosis. Immunohistochemical staining and tissue-specific markers can be helpful.

Use superb microvascular imaging to diagnose and predict metastatic cervical lymph nodes in patients with papillary thyroid carcinoma.

PURPOSE: Papillary thyroid carcinoma (PTC) with metastatic lymph nodes (LNs) is closely associated with disease recurrence. This study accessed the value of superb microvascular imaging (SMI) in the diagnosis and prediction of metastatic cervical LNs in patients with PTC. METHODS: A total of 183 cervical LNs (103 metastatic and 80 reactive) from 116 patients with PTC were analysed. Metastatic cervical LNs were confirmed by pathology or/and cytology; reactive cervical LNs were confirmed by pathology or clinical features. The characteristic of conventional ultrasound (US) was extracted using univariate and multivariate analyses. The diagnostic performance of US and SMI were compared using the area under the receiver operating curve (AUC) with corresponding sensitivity and specificity. A nomogram was developed to predict metastatic LNs in patients with PTC, based on multivariate analyses. RESULTS: L/S < 2, ill-defined border, absence of hilum, isoechoic or hyperechoic, heterogeneous internal echo, peripheral or mixed vascular pattern on color Doppler flow imaging (CDFI) and SMI, and a larger SMI vascular index appeared more frequently in metastatic LNs in the training datasets than in reactive LNs (P < 0.05). The diagnostic sensitivity, specificity and accuracy of SMI vs US are 94.4% and 87.3%, 79.3% and 69.3%, and 87.6% and 79.1%, respectively; SMI combined with US exhibited a higher AUC [0.926 (0.877-0.975)] than US only [0.829 (0.759-0.900)]. L/S < 2, peripheral or mixed vascular type on CDFI, and peripheral or mixed vascular types on SMI were independent predictors of metastatic LNs with PTC. The nomogram based on these three parameters exhibited excellent discrimination, with an AUC of 0.926. CONCLUSION: SMI was superior to US in diagnosing metastatic LNs in PTC. US combined with SMI significantly improved the diagnostic accuracy of metastatic cervical LNs with PTC. SMI is efficacious for differentiating and predicting metastatic cervical LNs.

Clinical features combined with ultrasound characteristics to predict TERT promoter mutations in papillary thyroid carcinoma: a single-center study over the past 5 years.

Purpose: Telomerase reverse transcriptase (TERT) has been reported in papillary thyroid carcinoma (PTC). This study aimed to investigate the correlation of TERT promoter mutations with clinical and ultrasound (US) features in PTC and to develop a model to predict TERT promoter mutations. Methods: Preoperative US images, postoperative pathological features, and TERT promoter mutation information were evaluated in 365 PTC patients confirmed by surgery. Univariate and multivariate factor analyses were performed to identify risk factors for TERT promoter mutations. A predictive model was established to assess the clinical predictive value. Results: Of the 365 patients with PTC (498 nodules), the number of those with TERT promoter mutations was 67 cases (75 nodules), and the number of those without mutations was 298 cases (423 nodules). The median age was 40 years in the wild-type group and 60 years in the mutant group. Male patients made up 35.82% of the mutant group and 22.82% of the wild-type group. Multivariate analysis revealed that the independent risk factors associated with the occurrence of TERT promoter mutation in PTC were as follows: older age (odds ratio (OR) = 1.07; p = 0.002), maximum diameter of ≥ 10 mm (OR = 3.94; p < 0.0001), unilateral (OR = 4.15; p < 0.0001), multifocal (OR = 7.69; p < 0.0001), adjacent to the thyroid capsule (OR = 1.94; p = 0.044), and accompanied by other benign nodules (OR = 1.94, p = 0.039). A predictive model was established, and the area under the curve (AUC) of the receiver operating characteristic was 0.839. TERT promoter mutations were associated with high-risk US and clinical features compared with the wild-type group. Conclusion: TERT promoter mutations were associated with older ages. They were also found to be multifocal, with a maximum diameter of ≥ 10 mm, unilateral, adjacent to the thyroid capsule, and accompanied by other benign nodules. The predictive model was of high diagnostic value.

Tumor growth manifested in two-fifths of low-risk papillary thyroid microcarcinoma patients during active surveillance: data from a tertiary center in China.

Purpose: To assess tumor growth using tumor doubling rate (TDR) during active surveillance (AS) in China. Methods: Between January 2016 and June 2020, a total of 219 patients with low-risk papillary thyroid microcarcinoma (PTMC) (aged 23-75 years) were consecutively enrolled in the AS program. Results: Four sections of TDR, >0.5, 0.1~0.5, -0.1~0.1 and <-0.1, corresponded with four categories of tumor volume kinetics: rapid growth, slow growth, stable, and decreased size. We found that 10.5% of PTMCs exhibited rapid growth, 33.33% exhibited slow growth, 26.48% were stable, and 29.68% decreased in size. Tumor growth was associated with two factors: age and volume of PTMC at diagnosis. 85.72% of elderly patients (≥ 61 years old) had tumors that remained stable or even shrank and rapidly growing tumors were not found in them. When the volume was small (≤14.13 mm3), the proportion of rapid growth was high (41.67%), whereas when the volume was large (> 179.5 mm3), the proportion of non-growth was 68.75%. Conclusion: TDR may be a better metric for evaluating tumor growth in observational PTMCs. A certain proportion of PTMCs grow during the period of AS and tumor growth was associated with age and volume of PTMC at initial diagnosis. Therefore, how to block tumor growth during the AS period, especially for young patients and patients with early-stage PTMC (size ≤ 5 mm), will be a new challenge.

Impact of age on central lymph nodes involvement in papillary thyroid cancer.

BACKGROUND: Total thyroidectomy is the main line of treatment for papillary thyroid cancer. Central lymph node dissection (CLND) is still debatable. In this study, we aimed to correlate the central lymph node status with the age of patients. METHODS: This is a retrospective study including patients with papillary thyroid cancer (PTC) who underwent total thyroidectomy and CLND at a tertiary cancer center during the period from January 2012 to September 2022. Patients were subdivided into 3groups: patients younger than 20 years old, patients between 20 and 40 years old, and patients older than 40 years old. Correlation between central lymph node status, lateral lymph node status, and harvest count with each other and between age groups was done. RESULTS: 315 patients were included. The younger the age group the higher the possibility of harboring positive central nodes, however, the positivity of lateral nodes was similar. Neither central nodal harvest nor positive central node count significantly differed between groups. The lateral nodal harvest was significantly higher in the < 20 years group with no affection to the number of positive nodes retrieved. The younger the age group the longer the disease-free survival (DFS). CONCLUSION: We can conclude that patients younger than twenty years had a higher probability of harboring malignancy in central nodes and higher lateral node harvest on dissection. In contrast, they do have a lower incidence of recurrence.

Functional analysis of ESM1 by shRNA-mediated knockdown of its expression in papillary thyroid cancer cells.

OBJECTIVE: Endothelial specific molecule-1 (ESM1) is implicated as an oncogene in multiple human cancers. However, the function of ESM1 in papillary thyroid cancer (PTC) is not well understood. The current study aimed to investigate the effect of ESM1 on the growth, migration, and invasion of PTC to provide a novel perspective for PTC treatment. METHODS: The expression levels of ESM1 in PTC tissues form 53 tumor tissue samples and 59 matching adjacent normal tissue samples were detected by immunohistochemical analysis. Knockdown of ESM1 expression in TPC-1 and SW579 cell lines was established to investigate its role in PTC. Moreover, cell proliferation, apoptosis, wound healing, and transwell assays were conducted in vitro to assess cell proliferation, migration and invasion. RESULTS: The findings revealed that ESM1 expression was significantly higher in PTC tissues than that found in paraneoplastic tissues (P<0.0001). Knockdown of ESM1 expression inhibited the proliferation, migration, and invasion of TPC-1 and SW579 cells in vitro. Compared with the control group, the mRNA and protein levels of ESM1 in PTC cells were significantly reduced following knockdown of its expression (P<0.01). In addition, ESM1-knockdown cells indicated decreased proliferation and decreased migratory and invasive activities (P<0.01, P<0.01, P<0.001, respectively). CONCLUSIONS: ESM1 was identified as a major gene in the occurrence and progression of PTC, which could increase the proliferation, migration, and invasion of PTC cells. It may be a promising diagnostic and therapeutic target gene.

Diagnostic value of high-frequency ultrasound combined with fine needle aspiration cytology and BRAF gene for papillary thyroid microcarcinoma.

We attempted to evaluate clinical application value of high-frequency ultrasound (HFUS), fine needle aspiration cytology (FNAC), BRAF gene, and combination of HFUS, FNAC, and BRAF gene in diagnosing papillary thyroid microcarcinoma (PTMC). The 150 patients with thyroid minimal lesions who underwent HFUS, FNAC and BRAF gene testing before surgery in our hospital from June 2020 to December 2021 were selected as research subjects. Patients were divided into two groups based on postoperative pathological results. The consistency of diagnostic results of HFUS, FNAC, and BRAF gene and their combination with those of pathological examination, diagnostic efficacy of HFUS, FNAC and BRAF gene combined detection and individual detection for PTMC lymph node metastasis, and diagnostic value of HFUS, FNAC and BRAF gene combined detection and individual detection for PTMC lymph node metastasis received analysis and comparison. The consistency of diagnostic results of combined detection with pathological examination exhibited elevation relative to that of HFUS, FNAC and BRAF gene detection alone (P < 0.05). The negative predictive value, sensitivity and accuracy of combined detection exhibited elevation relative to individual detection (P < 0.05). The AUC of combined detection in diagnosing PTMC lymph node metastasis exhibited elevation relative to that of HFUS and BRAF gene alone (P < 0.05). HFUS combined with FNAC and BRAF genes possesses high diagnostic value, with high diagnostic sensitivity, specificity, and accuracy. Thus, combined detection for PTMC before surgery can accurately determine whether lymph node metastasis occurs, reduce occurrence of missed diagnosis and misdiagnosis, and thus improve diagnostic precision.

Stimulated Raman Scattering Microscopy Reveals Aberrant Triglyceride Accumulation in Lymphatic Metastasis of Papillary Thyroid Carcinoma.

Lipid metabolic alterations are known to play a crucial role in cancer metastasis. As a key hub in lipid metabolism, intracellular neutral lipid accumulation in lipid droplets (LDs) has become a signature of aggressive human cancers. Nevertheless, it remains unclear whether lipid accumulation displays distinctive features in metastatic lesions compared to the primary ones. Here, we integrated multicolor stimulated Raman scattering (SRS) imaging with confocal Raman spectroscopy on the same platform to quantitatively analyze the amount and composition of LDs in intact human thyroid tissues in situ without any processing or labeling. Inspiringly, we found aberrant accumulation of triglycerides (TGs) in lymphatic metastases but not in normal thyroid, primary papillary thyroid carcinoma (PTC), or normal lymph node. In addition, the unsaturation degree of unsaturated TGs was significantly higher in the lymphatic metastases from patients diagnosed with late-stage (T3/T4) PTC compared to those of patients diagnosed with early-stage (T1/T2) PTC. Furthermore, both public sequencing data analysis and our RNA-seq transcriptomic experiment showed significantly higher expression of alcohol dehydrogenase-1B (ADH1B), which is critical to lipid uptake and transport, in lymphatic metastases relative to the primary ones. In summary, these findings unravel the lipid accumulation as a novel marker and therapeutic target for PTC lymphatic metastasis that has a poor response to the regular radioactive iodine therapy.

Lateral lymph node metastasis in papillary thyroid cancer: Is there a difference between PTC and PTMC?

Papillary thyroid carcinoma (PTC) and papillary thyroid microcarcinoma (PTMC) are generally characterized as less invasive forms of thyroid cancer with favorable prognosis. However, once lateral cervical lymph node metastasis takes place, the prognosis may be significantly impacted. The purpose of this study was to evaluate whether there is a difference in the pattern of lateral lymph node metastasis between PTC and PTMC. A retrospective analysis was performed for PTC and PTMC patients that underwent central area dissection and unilateral lateral neck lymph node dissection (II-V area) between January 2020 and December 2021. Compared with PTMC group, the PTC group exhibited higher incidence of capsule invasion, extrathyroid invasion and lymphatic vessel invasion. Both the number and rate of central lymph nodes metastasis were elevated in the PTC group. While the number of lateral cervical lymph node metastasis was higher, the metastasis rate did not demonstrate significant difference. No significant differences were identified in the lymph node metastasis patterns between the 2 groups. The determination of the extent of lateral neck lymph node dissection solely based on the tumor size may be unreliable, as PTC and PTMC showed no difference in the number and pattern of lateral neck metastasis. Additional clinical data are warranted to reinforce this conclusion. For patients categorized as unilateral, bilateral, or contralateral cervical lymph node metastasis (including level I, II, III, IV, or V) or retropharyngeal lymph node metastasis who require unilateral lateral neck dissection, the size of the primary tumor may not need to be a central consideration when assessing and deciding the extent of lateral neck dissection.

Predictors of treatment response in lymphogenic metastasized papillary thyroid cancer: a histopathological study.

BACKGROUND: Lymph node metastases in papillary thyroid cancer (PTC) increase the risk for persistent and recurrent disease. Data on the predictive value of histopathological features of lymph node metastases, however, are inconsistent. The aim of this study was to evaluate the prognostic significance of known and new histopathological features of lymph node metastases in a well-defined cohort of PTC patients with clinically evident lymph node metastases. METHODS: A total of 1042 lymph node metastases, derived from 129 PTC patients, were reexamined according to a predefined protocol and evaluated for diameter, extranodal extension, cystic changes, necrosis, calcifications, and the proportion of the lymph node taken up by tumor cells. Predictors for a failure to achieve a complete biochemical and structural response to treatment were determined. RESULTS: The presence of more than 5 lymph node metastases was the only independent predictor for a failure to achieve a complete response to treatment (odds ratio [OR] 3.39 [95% CI, 1.57-7.33], P < .05). Diameter nor any of the other evaluated lymph node features were significantly associated with the response to treatment. CONCLUSIONS: Detailed reexamination of lymph nodes revealed that only the presence of more than 5 lymph node metastases was an independent predictor of failure to achieve a complete response to treatment. No predictive value was found for other histopathological features, including the diameter of the lymph node metastases. These findings have the potential to improve risk stratification in patients with PTC and clinically evident lymph node metastases.

Clinicopathological Features and Molecular Signatures of Lateral Neck Lymph Node Metastasis in Papillary Thyroid Microcarcinoma.

BACKGRUOUND: The predictive factors for lateral neck lymph node metastasis (LLNM) in papillary thyroid microcarcinoma (PTMC) remain undetermined. This study investigated the clinicopathological characteristics, transcriptomes, and tumor microenvironment in PTMC according to the LLNM status. We aimed to identify the biomarkers associated with LLNM development. METHODS: We retrospectively reviewed the medical records of patients with PTMC from two independent institutions between 2018 and 2022 (n=597 and n=467). We compared clinicopathological features between patients without lymph node metastasis (N0) and those with LLNM (N1b). Additionally, laser capture microdissection and RNA sequencing were performed on primary tumors from both groups, including metastatic lymph nodes from the N1b group (n=30; 20 primary tumors and 10 paired LLNMs). We corroborated the findings using RNA sequencing data from 16 BRAF-like PTMCs from The Cancer Genome Atlas. Transcriptomic analyses were validated by immunohistochemical staining. RESULTS: Clinicopathological characteristics, such as male sex, multifocality, extrathyroidal extension, lymphatic invasion, and central node metastasis showed associations with LLNM in PTMCs. Transcriptomic profiles between the N0 and N1b PTMC groups were similar. However, tumor microenvironment deconvolution from RNA sequencing and immunohistochemistry revealed an increased abundance of tumor-associated macrophages, particularly M2 macrophages, in the N1b group. CONCLUSION: Patients with PTMC who have a male sex, multifocality, extrathyroidal extension, lymphatic invasion, and central node metastasis exhibited an elevated risk for LLNM. Furthermore, infiltration of M2 macrophages in the tumor microenvironment potentially supports tumor progression and LLNM in PTMCs.