Tall cell variant of papillary thyroid microcarcinoma: clinicopathologic features with BRAF(V600E) mutational analysis

A novel nomogram for identifying high-risk patients among active surveillance candidates with papillary thyroid microcarcinoma

Objective

Active surveillance (AS) has been recommended as the first-line treatment strategy for low-risk (LR) papillary thyroid microcarcinoma (PTMC) according to the guidelines. However, preoperative imaging and fine-needle aspiration could not rule out a small group of patients with aggressive PTMC with large-volume lymph node micro-metastasis, extrathryoidal invasion to surrounding soft tissue, or high-grade malignancy from the AS candidates.

Methods

Among 2,809 PTMC patients, 2,473 patients were enrolled in this study according to the inclusion criteria. Backward stepwise multivariate logistic regression analysis was used to filter clinical characteristics and ultrasound features to identify independent predictors of high-risk (HR) patients. A nomogram was developed and validated according to selected risk factors for the identification of an HR subgroup among "LR" PTMC patients before operation.

Results

For identifying independent risk factors, multivariable logistic regression analysis was performed using the backward stepwise method and revealed that male sex [3.91 (2.58-5.92)], older age [0.94 (0.92-0.96)], largest tumor diameter [26.7 (10.57-69.22)], bilaterality [1.44 (1.01-2.3)], and multifocality [1.14 (1.01-2.26)] were independent predictors of the HR group. Based on these independent risk factors, a nomogram model was developed for predicting the probability of HR. The C index was 0.806 (95% CI, 0.765-0.847), which indicated satisfactory accuracy of the nomogram in predicting the probability of HR.

Conclusion

Taken together, we developed and validated a nomogram model to predict HR of PTMC, which could be useful for patient counseling and facilitating treatment-related decision-making.

Utilizing Dynamic Risk Stratification in Patients With Tall Cell Variant Papillary Thyroid Cancer

OBJECTIVES

Tall cell variant (TCV) papillary thyroid cancer (PTC) is a subtype of PTC associated with aggressive tumor behavior, advanced stage, and higher rates of recurrence and mortality. The present study aimed to test an established dynamic risk stratification tool in the TCV population, with the goal of better predicting the postoperative course of these patients.

STUDY DESIGN

Retrospective chart review.

METHODS

A total of 94 patients with TCV who underwent total thyroidectomy with radioactive iodine ablation were retrospectively reviewed from 1998 through 2020. Biochemical, structural, and overall response to treatment was determined for each patient, based on postoperative thyroglobulin levels and imaging findings. Primary outcomes were locoregional and distant recurrence, presence of disease at final follow-up, need for additional intervention, and disease-specific mortality.

RESULTS

Patients with TCV who were stratified as having an excellent overall response to treatment had lower rates of locoregional recurrence than indeterminate, biochemical incomplete, and structural incomplete responses (2.0%, 33.3%, 55.0%, and 85.7% at 5 years respectively, p < 0.001). The same was true for distant recurrence as well (2.0%, 9.0%, 35.1%, and 42.9%, p < 0.001). An excellent response was also associated with lower rates of presence of disease at final follow-up, need for additional intervention, and disease-specific mortality.

CONCLUSIONS

Although TCV is an aggressive subtype associated with worse clinical outcomes than classical PTC, patients with an excellent overall response to treatment have significantly improved outcomes when compared to indeterminate, biochemical incomplete, and structural incomplete responses.

LEVEL OF EVIDENCE

3 Laryngoscope, 133:2430-2438, 2023.

The Presence of Typical "BRAFV600E-Like" Atypia in Papillary Thyroid Carcinoma is Highly Specific for the Presence of the BRAFV600E Mutation

Papillary thyroid carcinomas (PTCs) are driven by a variety of molecular abnormalities including BRAF, RAS, ALK, RET, and NTRK alterations. PTCs driven by the BRAFV600E mutation, or tumours which demonstrate a similar gene expression profile to PTCs driven by this mutation, have been reported to demonstrate specific morphological features sometimes termed "BRAFV600E-like" atypia. BRAFV600E-like atypia is characterised by a well-developed papillary architecture, infiltrative growth, marked nuclear clearing, prominent intranuclear pseudoinclusions, abundant eosinophilic cytoplasm, and scattered psammoma bodies. We sought to investigate the sensitivity and specificity of these morphological features for the presence of BRAFV600E mutation in PTCs as determined by mutation specific immunohistochemistry. An unselected cohort of 495 PTCs was reviewed by a single pathologist and categorised into three groups: typical BRAFV600E-like atypia (145 cases, 29%), possible BRAFV600E-like atypia (166 cases, 33%) and little/no BRAFV600E-like atypia (184 cases, 37%). The specificity and sensitivity of typical BRAFV600E-like atypia for the BRAFV600E mutation was 97.2% and 44.3%, respectively. When typical and possible BRAFV600E-like atypia were analysed together, the specificity was 70.6% and the sensitivity was 81.7%. In the morphologically little/no BRAFV600E-like atypia group, 58 cases (31.5%) had a BRAFV600E mutation. We conclude that typical BRAFV600E-like atypia is highly specific for the presence of the BRAFV600E mutation; however, the absence of BRAFV600E-like atypia does not exclude this mutation.

American Head and Neck Society Endocrine Surgery Section and International Thyroid Oncology Group consensus statement on mutational testing in thyroid cancer: Defining advanced thyroid cancer and its targeted treatment

BACKGROUND

The development of systemic treatment options leveraging the molecular landscape of advanced thyroid cancer is a burgeoning field. This is a multidisciplinary evidence-based statement on the definition of advanced thyroid cancer and its targeted systemic treatment.

METHODS

An expert panel was assembled, a literature review was conducted, and best practice statements were developed. The modified Delphi method was applied to assess the degree of consensus for the statements developed by the author panel.

RESULTS

A review of the current understanding of thyroid oncogenesis at a molecular level is presented and characteristics of advanced thyroid cancer are defined. Twenty statements in topics including the multidisciplinary management, molecular evaluation, and targeted systemic treatment of advanced thyroid cancer are provided.

CONCLUSIONS

With the growth in targeted treatment options for thyroid cancer, a consensus definition of advanced disease and statements regarding the utility of molecular testing and available targeted systemic therapy is warranted.

A cohort study of microwave ablation and surgery for low-risk papillary thyroid microcarcinoma

BACKGROUND

The optimal treatment method for papillary thyroid microcarcinoma (PTMC) is lacking consensus. Here we aimed to compare the efficacy and safety of surgery and microwave ablation (MWA) for PTMC.

METHODS

The clinical data of 644 patients with PTMC treated between July 2013 and June 2020 were retrospectively analyzed. A total of 320 and 324 patients underwent MWA and surgery, respectively. We observed lesion changes in the MWA group and compared the recurrence, metastasis, complications, and other health economic indicators between the 2 groups.

RESULTS

The mean follow-up time was 890.7 ± 532.9 (187.9-2679.0) days in the MWA group and 910.9 ± 568.4 (193.8-2821.5) days in the surgery group. In the MWA group, lesion volume increased significantly after ablation and then gradually decreased. The final lesion volume reduction rate was 90.73% ± 7.94%, and 193 lesions (60.3%) disappeared completely. There were no significant intergroup differences in recurrence or metastasis. The incidence of main complications (temporary hypothyroidism, hypoparathyroidism, and temporary hoarseness) was significantly lower in the MWA group than in the surgery group (p < 0.001). The treatment time, intraoperative blood loss, and hospital stay were significantly lower in the MWA group than in the surgery group (p < 0.001).

CONCLUSIONS

MWA is effective for treating PTMC, with a low incidence of complications and less trauma. The rates of post-treatment recurrence and metastasis are similar to those of surgery, indicating that MWA is a suitable alternative to surgery.

Rethinking Low-Risk Papillary Thyroid Cancers < 1cm (Papillary Microcarcinomas): An Evidence Review for Recalibrating Diagnostic Thresholds and/or Alternative Labels

Background: Recalibrating diagnostic thresholds or using alternative labels may mitigate overdiagnosis and overtreatment of papillary microcarcinoma (mPTC). We aimed at identifying and collating relevant epidemiological evidence on mPTC, to assess the case for recalibration and/or new labels. Methods: We searched EMBASE and PubMed databases from inception to December 2020 for natural history, autopsy, diagnostic drift, and diagnostic reproducibility studies. Where a relevant systematic review was pre-identified, only new articles were additionally included. Non-English articles were excluded. One author screened titles and abstracts. Two authors screened full text articles, performed quality assessments, and extracted data. We undertook narrative synthesis of included evidence (pooled estimates from systematic reviews and single estimates from primary studies). Results: One systematic review of patients undergoing active surveillance found that after 5 years of follow-up, 5.3% (95% confidence interval [CI 4.4-6.4%]) of the mPTC lesions had increased in size by ≥3 mm, and 1.6% [CI 1.1-2.4%] of patients had lymph node metastases. Among 7 new primary studies (including 3 updates on 2 studies included in the systematic review), 1-5% of patients undergoing active surveillance had lymph node metastases after a median follow-up of 1-10 years. One systematic review found that subclinical thyroid cancer incidentally discovered at autopsy is relatively common, with a pooled prevalence of 11.2% [CI 6.7-16.1%] among studies that examined the whole thyroid. Four diagnostic drift studies evaluated the new classification of non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP). Three studies of cases previously diagnosed as papillary thyroid cancer found 1.3-2.3% were reclassified as NIFTP (reclassifications were from follicular variation of papillary thyroid cancer [FVPTC]). One study of 48 cases previously diagnosed as mPTC found that 23.5% were reclassified as NIFTP. Thirteen reproducibility studies of papillary thyroid lesions found substantial variation in the histopathological diagnosis of thyroid lesions, including FVPTC and NIFTP classifications (no study evaluated mPTC). Conclusions: This review supports consideration of recalibrating diagnostic thresholds and/or alternative labels for low-risk mPTC.

Papillary thyroid microcarcinomas: does subtyping predict aggressive clinical behavior?

The most common malignant neoplasm affecting the thyroid gland is papillary thyroid carcinoma (PTC). PTC can demonstrate a number of morphologic variants including, but not limited to, classic, follicular, and tall cell. Each of these morphologic subtypes carry distinct clinical characteristics such that certain variants, like tall cell, behave more aggressively than others. PTCs measuring less than or equal to 1.0 cm are classified as microcarcinomas. Although these lesions are thought to be clinically indolent, we hypothesized that, like their larger counterparts, certain histologic variants may lead to worse patient outcomes. To test our hypothesis, we analyzed our pathology archives between the years 2009 and 2020 for papillary thyroid microcarcinomas and assessed whether different morphologic features correlated with more aggressive clinical behavior. Our findings suggest that certain variants exhibit features that portend a more worrisome clinical course and thus papillary thyroid microcarcinomas should be subtyped to help predict patient outcome.

Molecular Pathology of Non-familial Follicular Epithelial-Derived Thyroid Cancer in Adults: From RAS/BRAF-like Tumor Designations to Molecular Risk Stratification

This review addresses the impact of molecular alterations on the diagnosis and prognosis of differentiated thyroid carcinoma (DTC), including papillary, follicular, and well-differentiated carcinoma NOS, as well as oncocytic neoplasms. The molecular characterization of DTC is based upon the well-established dichotomy of BRAF-like and RAS-like designations, together with a remaining third group, less homogeneous, composed of non-BRAF-/non-RAS-like tumors. The role of BRAF V600E mutation in risk stratification is discussed in the clinico-pathological context, namely, staging and invasive features of classic papillary thyroid carcinoma (PTC) and histopathological variants carrying an excellent prognosis (microPTC) or a guarded prognosis, including the aggressive variants tall cell and hobnail cell PTCs. In follicular patterned tumors, namely, follicular thyroid carcinoma (FTC), with or without oncocytic features, the most prevalent molecular alteration are RAS mutations that do not carry prognostic significance. The only genetic alteration that has been proven to play a role in risk stratification of PTC and FTC is TERT promoter (TERTp) mutation.

Preoperative Typing of Thyroid and Parathyroid Tumors with a Combined Molecular Classifier

In previous studies, we described a method for detecting and typing malignant tumors of the thyroid gland in fine-needle aspiration biopsy samples via analysis of a molecular marker panel (normalized HMGA2 mRNA level; normalized microRNA-146b, -221, and -375 levels; mitochondrial-to-nuclear DNA ratio; and BRAF^V600E mutation) in cytological preparations by quantitative PCR. In the present study, we aimed to estimate the specificity of the typing of different thyroid tumors by the proposed method. Fine-needle aspiration cytological preparations from 278 patients were used. The histological diagnosis was known for each sample. The positive and negative predictive values of the method assessed in this study were, respectively, 100% and 98% for papillary thyroid carcinoma (n = 63), 100% and 100% for medullary thyroid carcinoma (n = 19), 43.5% and 98% for follicular carcinoma (n = 15), and 86% and 100% for Hürthle cell carcinoma (n = 6). Thus, we demonstrate that the diagnostic panel, including the analysis of microRNA expression, mRNA expression, the BRAF^V600E mutation, and the mitochondrial-to-nuclear DNA ratio, allows the highly accurate identification of papillary thyroid carcinoma, medullary thyroid carcinoma, and Hürthle cell carcinoma but not malignant follicular tumors (positive predictive value was below 50%).

Molecular characterisation and clinical correlation of papillary thyroid microcarcinoma

PURPOSE

Papillary thyroid microcarcinoma (mPTC) is defined as a papillary thyroid cancer sized 10 mm or less. Despite their generally indolent clinical course and good prognosis, a subset of mPTCs shows potentially aggressive behaviour.

METHODS

To search for predictors of clinical outcome of mPTCs, we retrospectively evaluated the genetic tumour profile of 100 patients (23 M/77 F, mean age ± SD 53.8 ± 13.4 years) with histologically confirmed mPTCs through analysis of BRAF, NRAS and TERT promoter mutations as well as RET/PTC translocations.

RESULTS

Mean follow-up period was 8.4 ± 3.6 years. In 55 cases, mPTC were detected incidentally after surgery. Capsular invasion, bilateralism and multifocality were found in 11/100, 17/100 and 24/100 cases, respectively, while lymph-nodes metastases were present at diagnosis in 9/100 cases. After 3.5 ± 2.0 years, tumour relapse occurred in 6/100 cases and was locoregional in five (two in the thyroid bed, three in laterocervical lymph-nodes), while lung metastasis occurred in one case. Biochemical persistence of disease was seen in 1/100 case. Mutations occurred in 55/100 cases; BRAF^V600E was the most frequently detected (49/100) and was associated with higher tumour size, bilateralism and follicular variant but not with capsular invasion. RET/PTC rearrangements were found in 2/100 cases, NRAS^Q61R in 4/100, while no mutations of TERT promoter gene were detected. Despite the observed association between BRAF^V600E mutation and unfavourable histopathological features, we found no direct association with tumour recurrence, distant metastases and mortality.

CONCLUSION

In our study, the search for the most frequent genetic alterations as prognostic markers in mPTCs would not have changed the therapeutic strategy.

Thyroid Papillary Microtumor: Validation of the (Updated) Porto Proposal Assessing Sex Hormone Receptor Expression and Mutational BRAF Gene Status

Given the high incidence and excellent prognosis of many papillary thyroid microcarcinomas, the Porto proposal uses the designation papillary microtumor (PMT) for papillary microcarcinomas (PMCs) without risk factors to minimize overtreatment and patients' stress. To validate Porto proposal criteria, we examined a series of 190 PMC series, also studying sex hormone receptors and BRAF mutation. Our updated Porto proposal (uPp) reclassifies as PMT incidental PMCs found at thyroidectomy lacking the following criteria: (a) detected under the age of 19 years; (b) with multiple tumors measuring >1 cm adding up all diameters; and (c) with aggressive morphologic features (extrathyroidal extension, angioinvasion, tall, and/or hobnail cells). PMCs not fulfilling uPp criteria were considered "true" PMCs. A total of 102 PMCs were subclassified as PMT, 88 as PMC, with no age or sex differences between subgroups. Total thyroidectomy and iodine-131 therapy were significantly more common in PMC. After a median follow-up of 9.6 years, lymph node metastases, distant metastases, and mortality were only found in the PMC subgroup. No subgroup differences were found in calcifications or desmoplasia. Expression of estrogen receptor-α and estrogen receptor-β, progesterone receptor, and androgen receptor was higher in PMC than in nontumorous thyroid tissue. BRAF mutations were detected in 44.7% of PMC, with no differences between subgroups. In surgical specimens, the uPp is a safe pathology tool to identify those PMC with extremely low malignant potential. This terminology could reduce psychological stress associated with cancer diagnosis, avoid overtreatment, and be incorporated into daily pathologic practice.

Dedifferentiated and undifferentiated neoplasms: A conceptual approach

This review provides a conceptual approach to dedifferentiation across a variety of tumor types, with particular attention to genetic events that tie together morphologically disparate areas of these neoplasms. First, working definitions of the terms differentiated, undifferentiated, and dedifferentiated are developed. Then, specific examples of tumors with a particular propensity for undergoing dedifferentiation are highlighted, with emphasis on both immunohistochemical studies and molecular lesions that enable surgical pathologists to establish diagnostic clarity in morphologically vexing situations. Throughout this review, the historical arc of the literature is followed, and therefore the discussion of specific tumor types begins with dedifferentiated chondrosarcoma, the neoplasm that inspired the terminology regarding dedifferentiation that remains in use today. Selected other sarcomas with well-established pathways of dedifferentiation are subsequently discussed, followed by descriptions of this process in subtypes of carcinoma and melanoma.

Tumor border pattern and size help predict lymph node status in papillary microcarcinoma: A clinicopathologic study

OBJECTIVE

Lymph node metastasis occurs in a subset of papillary microcarcinoma patients. We aimed to analyze the differences between metastatic and non-metastatic papillary microcarcinomas in order to identify a high-risk subgroup that is likely to require more aggressive treatment.

MATERIALS AND METHODS

126 thyroidectomies with lymph node dissections (central ± lateral), diagnosed as papillary microcarcinoma, were reviewed.

RESULTS

Mean age of 126 patients (F/M = 3.3) was 42 years. Mean size of the largest tumor was 7 mm. Classical was the most frequently (89%) encountered subtype. Multiple histologic subtypes co-occurred in 19%. Lymphovascular invasion was present in 16% (n = 20). 55 (44%) and 71 (56%) cases were unifocal and multifocal, respectively. 90 cases (71%) were non-encapsulated with overall infiltrative tumor borders, whereas in 36 cases (29%), the tumor had a well-defined capsule. Among those, 23 (64%) had tumor capsule invasion. 47 (37%) cases had metastasis in lymph nodes. In univariate analysis, metastasis was associated with tumor size of >5 mm (p = 0.02), tumor burden of >5 mm (p = 0.03), lymphovascular invasion (p = 0.02) and non-encapsulation (p = 0.01). No associations were found regarding sex, age, histologic subtype, lymphocytic thyroiditis, tumor capsule invasion (in capsulated tumors), laterality and multifocality (p > 0.05). In multivariate analysis, lymphovascular invasion (p = 0.01, OR = 3.97, 95% CI 1.35-11.67), tumor size >0.5 cm (p = 0.031, OR = 2.92, 95% CI 1.10-7.71) and non-encapsulation (p = 0.033, OR = 2.85, 95% CI 1.08-7.51) were independent risk factors.

CONCLUSION

Size (largest tumor or sum of all foci) of >5 mm, non-encapsulation and lymphovascular invasion were independent predictors of LNM in PMs. Unifocal tumors metastasize the same as multifocal tumors, suggestive of the contribution of other factors. Patients with sporadically resected microcarcinomas should be carefully followed-up, especially those that harbor risk factors in histology.

Prophylactic Central Lymph Node Dissection Improves Disease-Free Survival in Patients with Intermediate and High Risk Differentiated Thyroid Carcinoma: A Retrospective Analysis on 399 Patients

The role of prophylactic central lymph node dissection (pCLND) in the treatment of differentiated thyroid cancer (DTC) is controversial and still a matter of debate. The primary outcome of our study was to assess whether pCLND is effective in reducing the incidence of recurrent disease, and the secondary goal was to estimate the incidence of postoperative complications in patients who underwent pCLND and to evaluate the prognostic value of occult node metastases. In this retrospective study, we included patients with preoperative diagnosis of DTC and clinically uninvolved lymph nodes (cN0). The patients were divided into two groups, depending on the surgical approach: total thyroidectomy alone (TT group) or total thyroidectomy and pCLND (pCLND group). Three hundred and ninety-nine patients were included in this study, 320 (80.2%) in the TT group and 79 (19.8%) in the pCLND group. There were no significant differences in morbidity among the two groups. Histopathological evaluation demonstrated a similar distribution of aggressive features, especially regarding multicentricity, extrathyroidal extension, and angioinvasivity between the two groups. Occult lymph node metastases were found in 20 (25.3%) patients in the pCLND group. Prophylactic CLND was effective in improving disease-free survival in patients with intermediate and high risk of disease recurrence (p = 0.0392); occult lymph node metastases resulted as a significant negative prognostic factor (p < 0.001).

The Efficacy and The Safety of Ultrasound-guided Ablation Therapy for Treating Papillary Thyroid Microcarcinoma

The prevalence of papillary thyroid microcarcinoma (PTMC) increases rapidly all around the world, but the management of PTMC hasn't reached a consensus. Recently, ultrasound-guided (US-guided) ablation therapy was introduced as a feasible treatment for low-risk PTMC. The clinical application of US-guided ablation therapy needs doctors' effort to investigate the efficacy and the safety of US-guided ablation in treating PTMC carefully. Although the present evidence showed some limitations, such as short-term study time spans and no randomized control design, in our perspective, US-guided thermal ablation therapy has good short-term efficacy and safety and is a promising PTMC's treatment in future clinical practice.

Predictive Factors of Recurrence in Patients with Differentiated Thyroid Carcinoma: A Retrospective Analysis on 579 Patients

Differentiated thyroid carcinoma (DTC) is usually associated with a favorable prognosis. Nevertheless, up to 30% of patients present a local or distant recurrence. The aim of this study was to assess the incidence of recurrence after surgery for DTC and to identify predictive factors of recurrence. We included in this retrospective study 579 consecutive patients who underwent thyroidectomy for DTC from 2011 to 2016 at our institution. We observed biochemical or structural recurrent disease in 36 (6.2%) patients; five-year disease-free survival was 94.1%. On univariate analysis, male sex, histotype, lymph node yield, lymph node metastasis, extrathyroidal invasion and multicentricity were associated with significantly higher risk of recurrence, while microcarcinoma was correlated with significantly lower risk of recurrence. On multivariate analysis, only lymph node metastases (OR 4.724, p = 0.012) and microcarcinoma (OR 0.328, p = 0.034) were detected as independent predictive factors of recurrence. Postoperative management should be individualized and commensurate with the risk of recurrence: Patients with high-risk carcinoma should undergo strict follow-up and aggressive treatment. Furthermore, assessment of the risk should be repeated over time, considering individual response to therapy.

Management of the Patient with Aggressive and Resistant Papillary Thyroid Carcinoma

PURPOSE

Papillary carcinoma is the most frequent type of thyroid cancer and was considered the most benign of all thyroid carcinomas, with a low risk of distant metastases. However, there are some variants of papillary thyroid carcinoma that have affinity to spread in many organs, such as: lymph nodes, lungs and bones.

AIM

The aim of this study was presentation of a case with papillary carcinoma of the thyroid gland, very persistent and resistant in treatment with I 131.

MATERIAL AND RESULTS

A man 56 years old were diagnosed with papillary carcinoma of thyroid gland. He underwent a surgical removal of the tumor and right lobe of thyroid gland. With histopathology examination, were confirmed follicular variant of papillary carcinoma pT4. Two weeks later he underwent total thyroidectomy and was treated with 100 mCi of J 131. Six months later, the value of thyroglobulin was found elevated above upper measured limits (more than 500 ng/ml). Patient underwent surgical removal of 10 metastatic lymph nodes in the left side of the neck and has been treated with 145 mCi of radioiodine I 131. The examination after 5 months shows elevation of thyroglobulin, more than 20000 ng/ml and focally uptake of J 131 in the left lung. Patient was treated once again with 150 mCi radioiodine J 131. Whole body scintigraphy was registered focal uptake of radioiodine in the middle of the left collarbone. After a month, patient refers the enlargement of the lymph node in the right side of the neck. Currently patient is being treated with kinase inhibitor drug sorafenib and ibandronate. We have identified first positive response in treatment. Enlarged lymph node in the neck was reduced and the patient began feeling better.

CONCLUSION

This study suggests that some subtypes of papillary thyroid carcinoma appear to have more aggressive biological course. Subtypes of papillary thyroid carcinoma such as diffuse sclerosing carcinoma, tall cell or columnar cell and insular variants, appears to have more aggressive biological course and need early detection and other kind of treatment.

A comparison of the clinicopathological features and prognoses of the classical and the tall cell variant of papillary thyroid cancer: a meta-analysis

Papillary thyroid cancer (PTC) accounts for 80–90% of all thyroid malignancies. The tall cell variant (TCV) is a rare aggressive histotype of PTC. We performed a meta-analysis to compare the clinicopathological characteristics and prognostic factors of TCV with those of classical papillary thyroid carcinoma (cPTC). A literature search was performed using the PubMed and EMBASE databases using Medical Subject Headings and keywords. Twenty studies that included 1871 patients with TCV and 75323 patients with cPTC were included in our meta-analysis. Odds ratios and confidence intervals were calculated for each study. Patients with TCV were associated with multifocality, higher TNM stage, extrathyroidal extension, vascular invasion, lymph node metastasis, distant metastasis, BRAF mutation, disease-specific survival, and overall survival. We found that TCV cases were associated with more aggressive clinicopathological characteristics and poorer prognoses than cPTC cases were. Our results suggest that TCV is a high-risk PTC that warrants aggressive treatment and follow-up strategies.

Tall cell variant of papillary thyroid carcinoma: current evidence on clinicopathologic features and molecular biology

Tall cell variant (TCV) of papillary thyroid carcinoma (PTC) has been recognized for the past few decades as an entity showing aggressive biological behavior; however, there is considerable controversy regarding the definition, clinical and pathological features of TCV because of its rarity and difficult diagnosis. No clinical features can accurately diagnose TCV. Thus, the results of histocytology, immunohistochemistry and molecular genetics tests have important clinical implications for diagnosis. Given the aggressiveness and the increased recurrence and poor survival rates, more aggressive treatment approach and rigorous follow-up is required for patients with TCV. In the present article, we undertook a comprehensive review to summarize and discuss the various aspects of this variant, from morphology to immunohistochemistry, and molecular abnormalities from a practical and daily practice-oriented point of view.

Pathologic Characteristics, Natural History, and Prognostic Implications of BRAFV600E Mutation in Pediatric Papillary Thyroid Carcinoma

The BRAF^V600E mutation is the most common genetic aberration in papillary thyroid cancer (PTC), found in up to 68% of PTC in adults where it is associated with aggressive features. The incidence of this mutation in pediatric PTC is less frequent, reported as 0%-20% in the past and up to 63% in one recent series. Data suggest the mutation is not associated with an aggressive course in children; however, there are limited numbers of reported case series, so the prognostic implications remain poorly understood. The aim of this retrospective study was to examine the histologic characteristics and clinical outcomes of BRAF positive pediatric PTC at a single institution. A 12-year retrospective review of all thyroidectomies performed at a tertiary medical center identified 59 pediatric cases with a surgical pathology diagnosis of PTC. Fifty patients had BRAF^V600E mutation analysis data and were selected for further study. BRAF^V600E mutations were present in 48% of cases (n = 24) and absent in 52% (n = 26). The molecular characteristics of the BRAF negative cases will further be evaluated in future studies. BRAF positive cases occurred in patients who were on average older than the BRAF negative patients. Classic histology PTC was present in both BRAF positive and negative cases; however, only cases with classic PTC histology were positive for the mutation. No patients died and BRAF mutation was not associated with an increased recurrence rate. Our study supports BRAF^V600E is more common in children than previously thought and does not portend a more aggressive clinical course.

The Genetics of Papillary Microcarcinomas of the Thyroid: Diagnostic and Prognostic Implications

Papillary microcarcinoma of the thyroid (mPTC) is defined by the WHO as a papillary thy-roid cancer measuring 10mm or less in diameter and it is nowadays a topic of intense debate among the members of the medical community due to its apparent “epidemic” rise. Although these tumors follow almost always an indolent clinical course and carry an excellent prognosis, it is known that a small sub-set may display a potentially aggressive behavior. Nevertheless, we still lack an accurate way of predict-ing those which will cause significant disease. In an attempt to address this problem, a number of clini-co-pathologic features have been studied as poor prognostic markers in mPTC, and their association with known genetic alterations in thyroid cancer has been evaluated. Herein we review the present knowledge concerning mPTC’s genetic profile, namely the prevalence of BRAF (V600E), RAS and TERT promoter mutations and RET/PTC and PAX8-PPARG rearrangements and report the results of the evaluation in the putative prognostic value of these genetic alterations in mPTC.

Aggressiveness of the tall cell variant of papillary thyroid carcinoma is independent of the tumor size and patient age

The tall cell variant (TCV) of papillary thyroid carcinoma (PTC) is characterized by tall columnar cells with a height of at least three times their width. TCV usually presents at an older age, has a larger size and exhibits more extrathyroidal extension and metastases than classical PTC. The current study compared TCV with the classical and follicular variants (CaFVs) of PTC to determine if, irrespective of the age at diagnosis and tumor size, TCV is more aggressive than its classical and follicular counterparts. A total of 16 (3.66%) patients with TCV were identified in a series of 437 patients with PTC from the Clinical University Hospital (Santiago de Compostela, Spain) between 1990 and 2010. The patient clinicopathological features and B-Raf proto-oncogene (BRAF)V600E mutational status were compared with 34 cases of CaFVs of PTC matched for tumor size and patient age. The TCV series included 11 females and 5 males aged 15–74 years (median, 57 years). In total, 15 (93.8%) patients underwent total or near-total thyroidectomy, 1 underwent lobectomy and 5 (31.3%) underwent lymph node dissection. In the TCV series, the tumor size ranged from 5–45 mm (median, 19 mm). Compared with the CaFVs, the TCV of PTC exhibited a significantly higher prevalence of extrathyroidal extension [9/16 (56.3%) vs. 5/34 (14.7%) cases; P=0.007], lymph node metastases [9/16 (56.3%) vs. 9/34 (26.4%) cases; P=0.04], stage III/IV at presentation [10/16 (62.5%) vs. 7/34 (20.5%) cases; P=0.009] and BRAFV600E mutation [12/16 (80.0%) vs. 7/25 (28.0%) cases; P=0.004]. The TCV series also harbored more multifocal papillary carcinomas (50.0% vs. 26.4%), lymphovascular invasion (37.5% vs. 29.4%) and distant metastases (6.2% vs. 0.0%), as compared with the matched patient cohort. In conclusion, the TCV of PTC is frequently associated with BRAFV600E mutation and is more aggressive than the CaFVs of PTC, regardless of tumor size and patient age at diagnosis.

Ultrasonographic imaging of papillary thyroid carcinoma variants

Ultrasonography (US) is routinely used to evaluate thyroid nodules. The US features of papillary thyroid carcinoma (PTC), the most common thyroid malignancy, include hypoechogenicity, spiculated/microlobulated margins, microcalcifications, and a nonparallel orientation. However, many PTC variants have been identified, some of which differ from the classic type of PTC in terms of biological behavior and clinical outcomes. This review describes the US features and clinical implications of the variants of PTC. With the introduction of active surveillance replacing immediate biopsy or surgical treatment of indolent, small PTCs, an understanding of the US characteristics of PTC variants will facilitate the individualized management of patients with PTC.

Clinicopathological Features and Prognosis of Papillary Thyroid Microcarcinoma for Surgery and Relationships with the BRAFV600E Mutational Status and Expression of Angiogenic Factors

Objective

To investigate the clinicopathological characteristics of papillary thyroid microcarcinoma (PTMC) for surgery by comparing the difference between PTMC and larger papillary thyroid carcinoma (LPTC).

Methods

We analyzed the differences in the clinicopathological characteristics, prognosis, B-type RAF kinase (BRAF)^V600E mutational status and expression of angiogenic factors, including pigment epithelium-derived factor (PEDF), Vascular Endothelial Growth Factor (VEGF), and hypoxia-inducible factor alpha subunit (HIF-1α), between PTMC and LPTC by retrospectively reviewing the records of 251 patients with papillary thyroid carcinoma, 169 with PTMC, and 82 with LPTC (diameter >1 cm).

Results

There were no significant differences in the gender, age, multifocality, Hashimoto’s thyroiditis, TNM stage, PEDF protein expression, rate of recurrence, or mean follow-up duration between patients with PTMC or LPTC. The prevalence of extrathyroidal invasion (EI), lymph node metastasis (LNM), and BRAF mutation in patients with PTMC was significantly lower than in patients with LPTC. In addition, in PTMC patients with EI and/or LNM and/or positive BRAF (high-risk PTMC patients), the prevalence of extrathyroidal invasion, Hashimoto's disease, lymph node metastasis, tumor TNM stage, PEDF positive protein expression, the rate of recurrent disease, and the mRNA expression of anti-angiogenic factors was almost as high as in patients with larger PTC, but with no significant difference.

Conclusions

Extrathyroid invasion, lymph node metastases, and BRAF^V600E mutation were the high risk factors of PTMC. PTMC should be considered for the same treatment strategy as LPTC when any of these factors is found. Particularly, PTMC with BRAF^V600E gene mutations needed earlier surgical treatment. In addition, the high cell subtype of PTMC with BRAF^V600E gene mutation is recommended for total thyroidectomy in primary surgery to reduce the risk of recurrence.

Association of BRAF V600E Mutation and MicroRNA Expression with Central Lymph Node Metastases in Papillary Thyroid Cancer: A Prospective Study from Four Endocrine Surgery Centers

BACKGROUND

Studies have demonstrated an association of the BRAF(V600E) mutation and microRNA (miR) expression with aggressive clinicopathologic features in papillary thyroid cancer (PTC). Analysis of BRAF(V600E) mutations with miR expression data may improve perioperative decision making for patients with PTC, specifically in identifying patients harboring central lymph node metastases (CLNM).

METHODS

Between January 2012 and June 2013, 237 consecutive patients underwent total thyroidectomy and prophylactic central lymph node dissection (CLND) at four endocrine surgery centers. All tumors were tested for the presence of the BRAF(V600E) mutation and miR-21, miR-146b-3p, miR-146b-5p, miR-204, miR-221, miR-222, and miR-375 expression. Bivariate and multivariable analyses were performed to examine associations between molecular markers and aggressive clinicopathologic features of PTC.

RESULTS

Multivariable logistic regression analysis of all clinicopathologic features found miR-146b-3p and miR-146b-5p to be independent predictors of CLNM, while the presence of BRAF(V600E) almost reached significance. Multivariable logistic regression analysis limited to only predictors available preoperatively (molecular markers, age, sex, and tumor size) found miR-146b-3p, miR-146b-5p, miR-222, and BRAF(V600E) mutation to predict CLNM independently. While BRAF(V600E) was found to be associated with CLNM (48% mutated in node-positive cases vs. 28% mutated in node-negative cases), its positive and negative predictive values (48% and 72%, respectively) limit its clinical utility as a stand-alone marker. In the subgroup analysis focusing on only classical variant of PTC cases (CVPTC), undergoing prophylactic lymph node dissection, multivariable logistic regression analysis found only miR-146b-5p and miR-222 to be independent predictors of CLNM, while BRAF(V600E) was not significantly associated with CLNM.

CONCLUSION

In the patients undergoing prophylactic CLNDs, miR-146b-3p, miR-146b-5p, and miR-222 were found to be predictive of CLNM preoperatively. However, there was significant overlap in expression of these miRs in the two outcome groups. The BRAF(V600E) mutation, while being a marker of CLNM when considering only preoperative variables among all histological subtypes, is likely not a useful stand-alone marker clinically because the difference between node-positive and node-negative cases was small. Furthermore, it lost significance when examining only CVPTC. Overall, our results speak to the concept and interpretation of statistical significance versus actual applicability of molecular markers, raising questions about their clinical usefulness as individual prognostic markers.

Five Top Stories in Thyroid Pathology

CONTEXT

Thyroid carcinoma is the most common malignant tumor of endocrine organs, yet it only accounts for approximately 1% of all cancers in the United States with more than 35,000 new cases diagnosed each year and more than 450,000 people living with this disease. While most tumors can be diagnosed without much difficulty, a few tumor types, especially tumors with follicular pattern, sometimes pose a diagnostic challenge.

OBJECTIVE

To discuss morphologic, immunohistochemical, and molecular features of thyroid tumors. We also explore the clinicopathologic features of papillary microcarcinoma and medullary microcarcinoma and how the latter is related and differentiated from C-cell hyperplasia. Finally with the ever-growing list of organ systems involved in immunoglobulin (Ig) G4-related diseases, we discuss the still not completely explored IgG-4-related thyroid disease.

DATA SOURCES

Data were obtained from review of the pertinent peer-reviewed literature and institutional experience.

CONCLUSIONS

Histomorphologic evaluation still remains the gold standard for diagnosis in most cases of thyroid diseases. The application of ancillary studies such as immunohistochemistry and molecular diagnosis, including next-generation sequencing, is becoming more common.

Adjuvant Radioactive iodine 131 ablation in papillary microcarcinoma of thyroid: Saudi Arabian experience [corrected]

BACKGROUND

Papillary Microcarcinoma (PMC) of thyroid is a rare type of differentiated thyroid cancer (DTC), which according to the World Health Organization measures 1.0 cm or less. The gold standard of treatment of PMC is still controversy. Our aim was to contribute in resolving the debate on the therapeutic choices of the surgical and adjuvant I-131 (RAI) treatment in PMC.

METHODS

From 2000 to 2012, 326 patients were found to have PMC and were retrospectively reviewed for clinicopathological characteristics, treatment outcomes and prognostic factors.

RESULTS

Mean age of cohort was 42.6 years (range: 18-76) and the mean tumor size was 0.61 cm ± 0.24; lymph node involvement was seen in 12.9 % of cases. Median follow up period was 8.05 years (1.62-11.4). Total 23 all site recurrences (7.13 %) were observed; more observed in patients without I-131 ablation (p <0.0001). Ten year DFS rates were 89.6 %. Cox regression Model analysis revealed size, histopathologic variants, multifocality, extrathyroidal extension, lymphovascular space invasion, nodal status, and adjuvant RAI ablation the important prognostic factors affecting DFS.

DISCUSSION

Despite excellent DFS rates, a small proportion of patients with PMC develop recurrences after treatment. Adjuvant RAI therapy improves DFS in PMC patients with aggressive histopathologic variants, multifocality, ETE, LVSI, tumor size (> 0.5 cm) and lymph node involvement. Failure of RAI ablation to decrease risk in N1a/b supports prophylactic central neck dissection during thyroidectomy, however more trials are warranted.

CONCLUSION

Adjuvant I-131 ablation following thyroidectomy in PMC patients, particularly with poor prognostic factors improves DFS rates.

Genetic Alterations in Hungarian Patients with Papillary Thyroid Cancer

The incidence of thyroid cancers is increasing worldwide. Some somatic oncogene mutations (BRAF, NRAS, HRAS, KRAS) as well as gene translocations (RET/PTC, PAX8/PPAR-gamma) have been associated with the development of thyroid cancer. In our study, we analyzed these genetic alterations in 394 thyroid tissue samples (197 papillary carcinomas and 197 healthy). The somatic mutations and translocations were detected by Light Cycler melting method and Real-Time Polymerase Chain Reaction techniques, respectively. In tumorous samples, 86 BRAF (44.2%), 5 NRAS (3.1%), 2 HRAS (1.0%) and 1 KRAS (0.5%) mutations were found, as well as 9 RET/PTC1 (4.6%) and 1 RET/PTC3 (0.5%) translocations. No genetic alteration was seen in the non tumorous control thyroid tissues. No correlation was detected between the genetic variants and the pathological subtypes of papillary cancer as well as the severity of the disease. Our results are only partly concordant with the data found in the literature.

The Risk of Relapse in Papillary Thyroid Cancer (PTC) in the Context of BRAFV600E Mutation Status and Other Prognostic Factors

INTRODUCTION

The risk of over-treatment in low-advanced PTC stages has prompted clinicians to search for new reliable prognostic factors. The presence of BRAF mutation, the most frequent molecular event in PTC, seems to be a good candidate. However, there is still lack of randomised trials and its significance has been proved by retrospective analyses, involving a large group of patients. The question arises whether this factor is useful in smaller populations, characterised for specialised centres. Thus, the aim of the study was to evaluate the use of BRAF mutation as a potential predictive marker in PTC patients.

MATERIAL

233 PTC subjects treated between 2004-2006, were retrospectively analysed. Stage pT1 was diagnosed in 64.8% patients and lymph node metastases in 30.9%. Median follow-up was 7.5 years. BRAFV600E mutation was assessed postoperatively in all cases.

RESULTS

BRAF V600E mutation was found in 54.5%. It was more frequent in patients > 45 years (p=0.0001), and associated with larger tumour size (p=0.004). Patients with tumours <= 10 mm were over-represented among BRAF negative population (p=0.03). No association between BRAF mutation and other clinicopathological factors was observed. BRAF status was associated neither with relapse nor with disease-free survival (DFS) (p=0.76). Nodal status, extrathyroidal invasion and tumour size significantly influenced DFS.

CONCLUSION

The risk of PTC recurrence is mainly related to the presence of lymph node metastases and extrathyroidal invasion, whereas no impact of BRAF V600E mutation has been demonstrated.

Classic papillary thyroid carcinoma with tall cell features and tall cell variant have similar clinicopathologic features

Background

The tall cell variant of papillary thyroid carcinoma (TCVPTC) is more aggressive than classic papillary thyroid carcinoma (PTC), but the percentage of tall cells needed to diagnose TCVPTC remains controversial. In addition, little is known about the clinicopathologic features of classic PTC with tall cell features (TCF).

Methods

We retrospectively selected and reviewed the clinicopathologic features and presence of the BRAF mutation in 203 cases of classic PTC, 149 cases of classic PTC with TCF, and 95 cases of TCVPTCs, which were defined as PTCs having <10%, 10-50%, and ≥50% tall cells, respectively.

Results

TCVPTCs and classic PTCs with TCF did not vary significantly in clinicopathologic characteristics such as pathologic (p) T stage, extrathyroidal extension, pN stage, lateral lymph node metastasis, or BRAF mutations; however, these features differed significantly in TCVPTCs and classic PTCs with TCF in comparison to classic PTCs. Similar results were obtained in a subanalysis of patients with microcarcinomas (≤1.0 cm in size).

Conclusions

Classic PTCs with TCF showed a similar BRAF mutation rate and clinicopathologic features to TCVPTCs, but more aggressive characteristics than classic PTCs.

Papillary thyroid microcarcinoma: how to diagnose and manage this epidemic?

The incidence of papillary thyroid microcarcinoma (PTmC) has been increasing everywhere due to the improvement of imaging and morphological diagnoses and probably also due to environmental alterations. Despite this, the mortality caused by thyroid cancer has not increased, reflecting the low clinical aggressiveness of most papillary thyroid carcinomas (PTCs) and the quality of the available treatment. The criteria used to classify PTmC remain questionable, making the clinical risk evaluation of these lesions very difficult. There is no solid basis for establishing the most appropriate tumor size (currently <10 mm) to distinguish PTmC from PTC. Moreover, PTmCs encompass all sorts of PTC histotypes, thus turning the whole group of PTmC genetically and biologically heterogeneous. In this review, we address the 2 most interesting issues from a practical standpoint: Are there any specific morphological or molecular features distinguishing PTmC from PTC? Is it possible to predict the clinical behavior of PTmC in fine needle aspiration biopsy and in surgical specimens, using morphological and/or molecular markers?

Assessment of cellularity, genomic DNA yields, and technical platforms for BRAF mutational testing in thyroid fine-needle aspirate samples

BACKGROUND

BRAF mutation V600E (substitution Val600Glu) is a molecular signature for papillary thyroid carcinoma (PTC). Testing for BRAF mutation is clinically useful in providing prognostic prediction and facilitating accurate diagnosis of PTC in thyroid fine-needle aspirate (FNA) samples.

METHODS

This study assessed the correlation of cellularity with DNA yield and compared 2 technical platforms with different sensitivities in detection of BRAF mutation in cytologic specimens. Cellularity was evaluated based on groups of 10+ cells on a ThinPrep slide: 1+ (1-5 groups), 2+ (6-10 groups), 3+ (11-20 groups), and 4+ (> 20 groups). Genomic DNA was extracted from residual materials of thyroid FNAs after cytologic diagnosis.

RESULTS

Approximately 49% of thyroid FNA samples had low cellularity (1-2+). DNA yield is proportionate with increased cellularity and increased nearly 4-fold from 1+ to 4+ cellularity in cytologic samples. When applied to BRAF mutational assay, using a cutoff of 6 groups of follicular cells with 10+ cells per group, 96.7% of cases yielded enough DNA for at least one testing for BRAF mutation. Five specimens (11.6%) with lower cellularity did not yield sufficient DNA for duplicate testing. Comparison of Sanger sequencing to allele-specific polymerase chain reaction methods shows the latter confers better sensitivity in detection of BRAF mutation, especially in limited cytologic specimens with a lower percentage of malignant cells.

CONCLUSIONS

This study demonstrates that by using 6 groups of 10+ follicular cells as a cutoff, nearly 97% of thyroid FNA samples contain enough DNA for BRAF mutational assay. Careful selection of a molecular testing system with high sensitivity facilitates the successful conduction of molecular testing in limited cytologic specimens. Cancer (Cancer Cytopathol) 2014;122:114-22 © 2013 American Cancer Society.