Classification of thyroid follicular cell tumors: with special reference to borderline lesions

Differentiating Thyroid Follicular Adenoma from Follicular Carcinoma via G-Protein Coupled Receptor-Associated Sorting Protein 1 (GASP-1)

Follicular neoplasms are classified as benign or malignant depending on the presence or absence of capsular and/or vascular invasion. Due to incomplete capsular penetration or equivocal vascular invasion, the evaluation of these features can be challenging using histologic examination. In the current study, we analyzed the involvement of G-protein coupled receptor-associated sorting protein 1 (GASP-1) in the development and progression of thyroid neoplasms. Affinity-purified anti-GASP-1 polyclonal antibodies were used for routine immunohistochemistry (IHC) analysis. Thyroid tissue microarrays containing normal thyroid tissue, follicular adenoma, follicular carcinoma, papillary thyroid carcinoma, and anaplastic carcinoma were analyzed. We found that the level of GASP-1 expression can differentiate follicular adenoma from follicular carcinoma. When numerous cases were scored for GASP-1 expression by a board-certified pathologist, we found that GASP-1 expression is 7-fold higher in thyroid malignant neoplasms compared to normal thyroid tissue, and about 4-fold higher in follicular carcinoma compared to follicular adenoma. In follicular adenoma tissues, we observed the presence of many mini-glands that are enriched in GASP-1 and some mini-glands contain as few as three cells. GASP-1 IHC also possesses several advantages over the conventional H&E and can be used to identify early thyroid cancer and monitor cancer progression.

Chondroblastoma: clinicopathological analyses of 307 cases from a single institution in China and the diagnostic value of the H3F3 K36M mutant antibody

AIMS

To elucidate the clinicopathological features and the diagnostic value of mutation specific antibody H3F3 K36M of chondroblastoma (CB) in China.

METHODS

Clinicopathological profiles were retrieved, and immunohistochemistry was performed on 185 CB specimens and the control group.

RESULTS

Our series included 307 patients with a mean age of 22.1 years. Long tubular bones (63.8%, 196/307) were most commonly involved, followed by short bones of the hands and feet (22.1%, 68/307), sesamoid bones (8.1%, 25/307), flat bones and irregular bones (5.9%, 18/307). The most commonly involved site was the proximal femur, followed by distal femur, proximal humerus and calcaneus. The average age in the long bones group (20.3 years) was significantly younger than the short bones group (24.9 years) (p<0.001), sesamoid bones group (24.4 years) (p=0.02) and flat bones and irregular bones group (29.1 years) (p<0.001). Microscopically, aneurysmal bone cyst-like change (63.6%, 117/184), necrosis (43.5%, 80/184) and chicken-wire calcification (26.1%, 48/184) were variably noted. In rare cases, cortical destruction, soft tissue and lymphovascular invasion were identified. Positive immunoreaction with H3F3 K36M was examined in all non-decalcified, all EDTA decalcified, 87.1% hydrochloric acid (HCl) decalcified CB samples and the high-grade sarcoma secondary to CB, but not the control group.

CONCLUSIONS

CB usually involves the long tubular bones in younger age group. H3F3 K36M can identify K36M mutation with 100% specificity and 100% sensitivity in non-decalcified and EDTA decalcified samples, more than 80% sensitivity in HCl decalcified samples. Virtually, all CBs harbour an H3K36M mutation.

Prognostic significance of neutrophil-to-lymphocyte ratio for long-term outcomes in patients with poorly differentiated thyroid cancer

Poorly differentiated thyroid cancer (PDTC) is a distinct but rare type of thyroid cancer with intermediate biological behavior between differentiated and anaplastic thyroid cancers. PDTC was first defined in 2005 in Japan, but the diagnostic criteria changed in 2015, requiring the tumor to have more than 50% of poorly differentiated components for diagnosis. Because only six years have passed since the PDTC definition change, prognostic factors for long-term survival who meet the latest criteria have not been determined. Neutrophil-to-lymphocyte ratio (NLR) is a prognostic marker in various solid malignancies. However, its impact on PDTC remains unclear. This study aimed to evaluate the significance of NLR as a prognostic factor for patients with PDTC diagnosed based on the latest criteria. In total, 28 PDTC cases (4.4%) of 637 thyroid cancer patients who underwent surgery between 2002 and 2012 were retrospectively analyzed. The median follow-up period was 120 months (range, 7-216 months). Of the 13 deaths (46.4%), 9 patients (32.1%) died from PDTC. The median preoperative NLR was 2.7 (0.67-8.62), and the NLR cut-off value determined by the receiver operating characteristic curve was 2.88. Patients with a high NLR (>2.88) showed significantly worse disease-specific survival (hazard ratio [HR] 4.67, p = 0.036) and overall survival (HR 4.94, p = 0.007) than those with a low NLR (≤2.88). Multivariate analysis revealed that a high NLR independently predicted a worse prognosis (HR 6.06, p = 0.0087). In conclusion, NLR is a useful prognostic marker for patients with PDTC.

Whole Tumor Capsule Is Prognostic of Very Good Outcome in the Classical Variant of Papillary Thyroid Cancer

CONTEXT

Tumor capsule integrity is becoming a relevant issue to predict the biological behavior of human tumors, including thyroid cancer.

OBJECTIVE

This work aims to verify whether a whole tumor capsule in the classical variant of papillary thyroid carcinoma (CVPTC) could have as a predictive role of a good outcome as for follicular variant (FVPTC).

METHODS

FVPTC (n = 600) and CVPTC (n = 554) cases were analyzed. We distinguished between encapsulated-FVPTC (E-FVPTC) and encapsulated-CVPTC (E-CVPTC) and, thereafter, invasive (Ei-FVPTC and Ei-CVPTC) and noninvasive (En-FVPTC and En-CVPTC) tumors, according to the invasion or integrity of the tumor capsule, respectively. Cases without a tumor capsule were indicated as invasive-FVPTC (I-FVPTC) and invasive-CVPTC (I-CVPTC). The subgroup of each variant was evaluated for BRAF mutations.

RESULTS

E-FVPTC was more frequent than E-CVPTC (P < .001). No differences were found between En-FVPTC and En-CVPTC or between Ei-FVPTC and Ei-CVPTC. After 18 years of follow-up, a greater number of not-cured cases were observed in Ei-CVPTC with respect to Ei-FVPTC, but not in En-CVPTC to En-FVPTC. Multivariate clustering analysis showed that En-FVPTC, En-CVPTC, and Ei-FVPTC have similar features but different from I-FVPTC and I-CVPTC and, to a lesser extent, from Ei-CVPTC. A total of 177 of 614 (28.8%) cases were BRAFV600E mutated, and 10 of 614 (1.6%) carried BRAF-rare alterations. A significantly higher rate of En-CVPTC (22/49, 44.9%) than En-FVPTC (15/195, 7.7%) (P < .0001) were BRAFV600E mutated.

CONCLUSION

En-CVPTC is less prevalent than En-FVPTC. However, it has good clinical/ pathological behavior comparable to En-FVPTC. This finding confirms the good prognostic role of a whole tumor capsule in CVPTC as well. New nomenclature for En-CVPTC, similar to that introduced for En-FVPTC (ie, noninvasive follicular thyroid neoplasm with papillary-like nuclear features; NIFTP) could be envisaged.

Intratumoral Heterogeneity in Differentiated Thyroid Tumors: An Intriguing Reappraisal in the Era of Personalized Medicine

Differentiated thyroid tumors (DTTs) are characterized by significant molecular variability in both spatial and temporal intra-tumoral heterogeneity (ITH), that could influence the therapeutic management. ITH phenomenon appears to have a relevant role in tumor growth, aggressive behavior and drug resistance. Accordingly, characteristics and consequences of ITH in DTTs should be better analyzed and understood in order to guide clinical practice, improving survival. Consequently, in the present review, we investigated morphological and molecular ITH of DTTs in benign, borderline neoplasms and in malignant entities, summarizing the most significant data. Molecular testing in DTTs documents a high risk for recurrence of cancer associated with BRAF^V600E, RET/PTC 1/3, ALK and NTRK fusions, while the intermediate risk may be related to BRAF^K601E, H/K/N RAS and PAX8/PPARγ. In addition, it may be suggested that tumor genotype is associated with peculiar phenotype.

Updates in the Pathologic Classification of Thyroid Neoplasms: A Review of the World Health Organization Classification

Advances in medical sciences and evidence-based medicine have led to momentous changes in classification and management of thyroid neoplasms. Much progress has been made toward avoiding overdiagnosis and overtreatment of thyroid cancers. The new 2017 World Health Organization (WHO) classification of thyroid neoplasms updated the diagnostic criteria and molecular and genetic characteristics reflecting the biology and behavior of the tumors, and newly introduced the category of borderline malignancy or uncertain malignant potential. Some neoplasms were subclassified, renamed, or redefined as a specific entity. This review introduces changes in the fourth edition WHO classification of thyroid tumors and updates the contemporary diagnosis and classification of thyroid tumors. We also discuss several challenges with the proposal of new diagnostic entities, since they have unique histopathologic and molecular features and clinical relevance.

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.

Active surveillance for low-risk small papillary thyroid cancer in North American countries: past, present and future (bridging the gap between North American and Asian practices)

Papillary thyroid cancer (PTC) is increasingly being diagnosed worldwide; yet the mortality remains very low, suggesting widespread overdiagnosis. While traditional management of PTC includes thyroid surgery, sometimes followed by radioactive iodine treatment, there is a global trend towards more conservative approaches for patients who are considered as the lowest risk of recurrence or death from their disease. Active surveillance (AS), once called watchful waiting, involves close follow-up, with the intention to intervene if the cancer progresses, or on patient request. The Kuma Hospital in Japan was the first to introduce AS as an alternative to immediate thyroid surgery for low-risk papillary thyroid microcarcinomas (PTMC, <1 cm) in 1993. Accumulated evidence over the years has shown that AS is a safe and effective approach in select patients, with a low rate of cancer progression during AS. Consequently, the Japanese Clinical Guidelines for treatment of thyroid tumor approved AS as a first-line management for patients with asymptomatic PTMC in 2010. Subsequently, the latest 2015 American Thyroid Association guidelines endorsed AS as an alternative approach to immediate surgery for cytologically confirmed very low-risk PTC. However, the acceptance, feasibility and results of AS in patients with low-risk PTC outside of Japan are still largely unknown. Most guidelines recommend that thyroid nodules <1 cm should not be aspirated but instead monitored regardless of the ultrasonographic characteristics. In essence, these patients are also being subjected to AS. Specific recommendations and the role of molecular testing for the optimal selection of PTMC patients for an AS management approach are not well established. Furthermore, research is needed to assess the long-term clinical and psychosocial outcomes in patients with larger tumor sizes (>1 cm) who undergo screening and diagnosis according to the North American guidelines and practices. The first Canadian prospective observational study launched in 2016 is intended to complement the existing data for AS of small low-risk PTC (≤2 cm) and may provide insight into the different approaches in North American and Asian practices. This review intends to summarize the development and the rationale of AS for PTMC and highlights significant differences between North American and Japanese practices.

Precursor and borderline lesions of the thyroid (indolent lesions of epithelial origin): from theory to practice

The precursor lesions of thyroid neoplasms can arise from either C cells or follicular cells. Although MTC has an established and recognized precursor lesion, the C-cell hyperplasia, the same does not occur for the follicular cell-derived tumors, which are much more frequent. One of the significant obstacles to recognizing follicular cell-derived precursor lesions (FCPL) is the lack of refinement of the morphological spectrum and biology of these putative premalignant lesions. What are the "gold standard" histological criteria in thyroid pathology to identify the progression of dysplasia to cancer? Diagnostical irreproducibility and misnomer in the terminology of some FCPLs have been lying behind the answer to this question. The last past decades' advances in molecular pathology allow us to transform the knowledge in thyroid pathology to cancer prevention and early detection, which will only be possible by improving our understanding of the nature of thyroid precursor and borderline lesions. This review, amassed with the augmented expertise of thyroid pathology documented in the literature, is an attempt at underlining the present understanding of precursor and borderline lesions of the thyroid, with a particular highlight on practice differences in Asian and Western geographies.

Distant metastases from pathologically proven benign follicular nodules of the thyroid: clinicopathological features and predictors of long-term survival

OBJECTIVE

Distant metastases are rarely observed in patients with initial pathologically proven benign follicular nodules of the thyroid. This study aimed to evaluate the clinicopathological features and independent variables associated with survival in such patients with distant metastases.

METHODS

In total, 10,992 consecutive differentiated thyroid cancer (DTC) patients treated with ¹³¹I after total or near-total thyroidectomy from 2000 to 2018 were retrospectively reviewed.

RESULTS

Thirty-nine patients with initial pathologically proven benign follicular nodules of the thyroid were enrolled. Among them, 26 were pathologically diagnosed as thyroid adenoma, 8 as benign nodular goiter, 4 as thyroid adenoma combined with benign nodular goiter, and 1 as normal thyroid tissue. Of 26 patients with the initial pathological slides obtained, eight cases were rediagnosed as minimally invasive thyroid carcinoma (MI-FTC), 10 as follicular tumor of uncertain malignant potential (FT-UMP), and five as well-differentiated tumor of UMP (WDT-UMP). Monitoring of thyroglobulin (Tg) changes after initial thyroidectomy and preablation-stimulated Tg (psTg) level were significantly associated with 5-year OS rate (P = 0.007 and P = 0.005, respectively). The presence of radioactive-refractory DTC (RR-DTC), monitoring of Tg changes after initial thyroidectomy, and psTg level had significant effects on 10-year OS rate (P = 0.002, P < 0.001, and P = 0.005, respectively). Lack of monitoring of Tg changes after initial thyroidectomy and RR-DTC were independent factors associated with poor prognosis (P = 0.003 and P = 0.008, respectively).

CONCLUSIONS

MI-FTC, FT-UMP, and WDT-UMP tended to be ignored and/or misdiagnosed as benign follicular lesions. Lack of monitoring of Tg changes after initial thyroidectomy and the presence of RR-DTC were identified as independent factors associated with poor survival.

Histopathologic Assessment of Capsular Invasion in Follicular Thyroid Neoplasms-an Observer Variation Study

The assessment of capsular invasion is an essential but challenging step in the diagnosis of encapsulated follicular thyroid neoplasms. Therefore, interobserver agreement in the assessment of capsular invasion in these tumors was investigated among 11 thyroid pathologists by using virtual slides of 20 cases in which the original diagnosis considered the differential diagnosis of definite capsular invasion versus questionable capsular invasion. The assessment of capsular invasion was divided into three categories: (1) non-invasive, (2) questionable invasive, and (3) clear-cut invasive. The interobserver agreements for clear-cut invasive and non-invasive categories were fair (Kappa value = 0.578 and 0.404, respectively), whereas agreement for the questionable invasion was poor (Kappa value = 0.186). Disagreements in the assessment of invasion resulted in variable final pathological diagnoses. For example, the agreement for a diagnosis of malignancy was only fair (Kappa value = 0.545). Moreover, pathologists did not have a uniform approach for rendering a final diagnosis in cases with questionable capsular invasion, though nine of 11 pathologists did use the follicular tumor of uncertain malignant potential diagnosis as proposed by the World Health Organization classification of endocrine organs published in 2017. In conclusion, this study revealed considerable interobserver variation in the evaluation of capsular invasion, especially in follicular neoplasms with questionable invasion.

First ever case report of co-occurrence of hobnail variant of papillary thyroid carcinoma and intrathyroid parathyroid adenoma in the same thyroid lobe

•

First reported case of hobnail variant of papillary thyroid cancer and Intrathyroid parathyroid adenoma occurring within same thyroid lobe.

•

Next-generation sequencing of the mutation spectrum of hobnail variant of papillary thyroid cancer showed BRAFV600E mutation.

•

Studies that define other molecular abnormalities may be useful as therapeutic targets.

Introduction

The hobnail variant of papillary thyroid cancer (PTC) is rare. Intrathyroid parathyroid adenoma (ITPA) is also rare. Co-ocurrence of PTC and ITPA in the same thyroid lobe is extremely rare. Likewise, primary hyperparathyroidism with such non-medullary thyroid carcinoma is rare. The specific molecular profile of hobnail PTC (HPTC) is different from the classic, poorly differentiated and anaplastic variants and may contribute to its aggressive behavior. HPTC’s genetic profile remains unclear.

Presentation of case

A 61-year-old woman presented to our endocrine clinic with generalized aches, bone pain, polyuria, and right neck swelling of a few months’ duration. Laboratory findings revealed hypercalcemia and hyperparathyroidism. Ultrasound of the neck showed 4.6 cm complex nodule within the right thyroid lobe. Sestamibi scan suggested parathyroid adenoma in the right thyroid lobe. Fine-needle aspiration (FNA) revealed atypical follicular lesion of undetermined significance. She underwent right lobectomy, which normalized the intraoperative intact parathyroid hormone levels. Final pathology with immunohistochemical stains demonstrated HPTC and IPTA (2 cm each). Next-generation sequencing investigated the mutation spectrum of HPTC and detected BRAFV600E mutation.

Conclusions

A parathyroid adenoma should not exclude the diagnosis of thyroid carcinoma. Thyroid evaluation is needed for patients with primary hyperparathyroidism to prevent missing concurrent thyroid cancers. Cytomorphologic features to distinguish thyroid from parathyroid cells on FNA cytology must be considered. Immunohistochemical stains are important. BRAFV600E is the most common mutation in HPTC. This is possibly the first reported case of HPTC and ITPA co-occurring within the same thyroid lobe. Studies that define other molecular abnormalities may be useful as therapeutic targets.

How to handle borderline/precursor thyroid tumors in management of patients with thyroid nodules

Thyroid carcinomas originating from follicular cells have the prognosis of heterogeneous diseases, but pathologists classify them all as malignant disease. Epidemiologists have issued a stern warning regarding over-diagnosis and overtreatment of patients with indolent thyroid tumors that cause no harm to the patients. Review of the literature revealed that there were several proposals of borderline/precursor tumors to some indolent thyroid carcinomas. Thyroid tumor of uncertain malignant potential (UMP) was first proposed by Williams for encapsulated follicular pattern thyroid tumors to solve problems due to observer variation. Rosai et al. proposed to rename papillary microcarcinoma (PMC) to papillary micro-tumor as the overwhelming majority of them are of no clinical significance. Liu et al. proposed well-differentiated tumor with uncertain behavior (WDT-UB) which covered WDT of UMP (WDT-UMP) and non-invasive encapsulated follicular variant of papillary thyroid carcinoma (EFVPTC). The EFVPTC without invasion was renamed as non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) by an international panel of pathologists. A new prognostic classification of thyroid tumors was proposed by Kakudo et al., in which extremely low risk tumors were grouped in a borderline tumors category. The borderline/precursor thyroid tumors included encapsulated tumors [capsular invasion only follicular carcinoma, encapsulated papillary carcinoma without invasion, WDT-UMP and follicular tumor of UMP (FT-UMP)] and non-encapsulated tumors (PMC). The UMP and NIFTP were incorporated in the 4th edition WHO classification of thyroid tumors as a new tumor entity in chapter 2-2A: other encapsulated follicular patterned thyroid tumors. Their behavior codes were decided to be 1 (borderline or uncertain behavior), and not 0 (benign), 2 (in situ carcinoma) or 3 (malignant). These borderline/precursor thyroid tumors are indolent tumors biologically and should be treated more conservatively than as previously recommended for thyroid follicular cell carcinomas [total thyroidectomy (TTX) followed by radio-active iodine (RAI) treatment] by western clinical guidelines.

Evaluation and Management of Indeterminate Thyroid Nodules: The Revolution of Risk Stratification Beyond Cytological Diagnosis

In accordance with National Guidelines, we currently follow a linear approach to the diagnosis of thyroid nodules, with management decision based primarily on a cytological diagnosis following fine-needle aspiration biopsy. However, 25% of these biopsies render an indeterminate cytology, leaving uncertainty regarding appropriate management. Individualizing the risk of malignancy of these nodules could improve their management significantly. We summarize the current evidence on the relevance of clinical information, radiological features, cytological features, and molecular markers tests results and describe how these can be integrated to personalize the management of thyroid nodules with indeterminate cytology. Several factors can be used to stratify the risk of malignancy in thyroid nodules with indeterminate cytology. Male gender, large tumors (>4 cm), suspicious sonographic patterns, and the presence of nuclear atypia on the cytology are all associated with an increased cancer prevalence. The added value of current molecular markers in the risk stratification process needs further study because their performance seems compromised in some clinical settings and remains to be validated in others. Risk stratification is possible in thyroid nodules with indeterminate cytology using data that are often underused by current guidelines. Future guidelines should integrate these factors and personalize the recommended diagnostic and therapeutic approaches accordingly.

Encapsulated follicular thyroid tumors of uncertain malignant potential in the new international histological classification

В 2017 г. Международное агентство по изучению рака (МАИР) выпустило в свет новое 4-е издание классификации ВОЗ опухолей эндокринных органов. Как и в предыдущем издании 2004 г., в новой классификации значительное место уделено опухолям щитовидной железы (ЩЖ). Экспертами ВОЗ пересмотрены критерии злокачественности инкапсулированных фолликулярных опухолей с ядрами папиллярного типа. Ранее такие опухоли относили к злокачественным новообразованиям (фолликулярному варианту папиллярного рака), а в новой классификации они получили статус пограничных, или опухолей неопределенного злокачественного потенциала (НЗП). Известно, что оценка злокачественного потенциала фолликулярных новообразований невозможна на этапе дооперационной цитологической диагностики в связи с отсутствием надежных соответствующих признаков. Она затруднена и в 10% случаев фолликулярных опухолей ЩЖ на этапе послеоперационной гистологической диагностики в связи с отсутствием очевидных морфологических проявлений инвазии в собственную капсулу и/или сомнительными для папиллярного рака изменениями ядер опухолевых клеток. В настоящей статье представлены критерии диагностики неинвазивной фолликулярной опухоли ЩЖ с ядрами папиллярного типа, а также еще двух классификационных категорий фолликулярных опухолей НЗП, к которым в соответствии с новой классификацией относятся фолликулярные и высокодифференцированные опухоли ЩЖ НЗП. Особое внимание уделено диагностической значимости инвазивного роста опухоли как основному морфологическому проявлению злокачественности фолликулярных опухолей. В связи с изменившимися критериями морфологической диагностики в статье вынесены на обсуждение вопросы качества гистологической диагностики, которое должно быть неизменно высоким, и влияния изменившейся классификации на лечебную тактику в случаях инкапсулированных фолликулярных опухолей.

Radioguided thyroidectomy for follicular tumors: Multicentric experience

BACKGROUND

The diagnosis of thyroid nodular diseases requires an integrated approach that has been widely established over the past years. This strategy includes: ultrasonography (US) with; implemented Color-Power-Doppler, conventional scintigraphy also with positive indicators, specific pathological studies targeted by immunohistochemically-assays, and the fine needle; aspiration biopsy (FNAB), which, usually, in case of "Follicular Lesions" (10-20%) findings is; unable to distinguish carcinoma from follicular adenoma, then indicating the necessity of surgery to; obtain a correct diagnosis. The aim of this study was to evaluate the role of the scintigraphy with; positive indicators, both preoperatively in diagnostic approach of the thyroid nodules and; intraoperatively as a guide to the extension of the surgical excision.

METHODS

On 4482 Thyroidectomy performed, we selected 360 cases of follicular neoplasms (192; females and 168 males). In the preoperative phase, these patients underwent 99 m Tc-sestaMIBI; scintigraphy with both early (10 min) and late (2 h) image acquisition, which were later; compared to the ones obtained by image subtraction of means 99 m Tc-pertechnetate. Following the; sestamibi administration before intervention, we selected the most up-taking nodularity with the; assistance of a specific surgical probe (Neoprobe), quantifying uptake with relation to the surgical pathology, for an amount of 324 total thyroidectomies and 36 hemi thyroidectomies.

RESULTS

In all cases of multinodular goiter the benign nodules showed an intraoperative low sestamibi uptake whereas follicular carcinomas showed both a high preoperative uptake and, as a; percentage, the highest values of intraoperative uptake; on the other hand, follicular adenomas had; both pre-and intraoperative mean values of uptake. On the contrary, papillary carcinomas only; showed a mild uptake.

CONCLUSIONS

Preoperative sestamibi scintigraphy confirmed its importance in improving the information obtained through different diagnostic investigations. Also intraoperatively, it pointed; out high-risk nodules more accurately. Therefore, radio (Sestamibi) guided surgery could have an; interesting rule in the thyroid follicular lesion treatment.

The Hobnail Variant of Papillary Thyroid Carcinoma: Clinical/Molecular Characteristics of a Large Monocentric Series and Comparison with Conventional Histotypes

BACKGROUND

The hobnail variant of papillary thyroid carcinoma (HPTC) has an aggressive behavior. The aims of this prospective study were to define the clinical/molecular characteristics of HPTC, and to compare them to those of conventional papillary thyroid carcinoma (PTC).

METHODS

From 2010 to 2016, 25 cases of HPTC, characterized clinically and molecularly (BRAF, RAS, TERT promoter, and TP53 mutations), were compared to a series of 165 consecutive cases of PTC. All patients underwent total thyroidectomy and received radioactive iodine treatment. Follow-up was available for 19 HPTC patients.

RESULTS

Among the HPTC patients, 64% had a hobnail component ≥30%, and 64% had multifocal disease. The mean tumor size was 30 mm; 96% of tumors were angio-invasive; 68% were N1, and 12% were M1; 58% harbored the BRAF^V600E mutation, 12% had a mutation in the TERT promoter, 17% had a TP53 mutation, and not had a RAS mutation. At a mean follow-up of 39 months, 32% of patients had biochemical and/or structural disease. Tumor size was the only significant difference between patients with persistent disease and those with an excellent response (40 mm and 24 mm, respectively; p = 0.02). Compared to the PTC control group, the HPTC patients had larger tumors (30 mm vs. 16 mm; p < 0.001), more frequent lymph node involvement (68% vs. 38%; p = 0.01), and remote disease (16% vs. 3%; p < 0.0001), a similar prevalence of the BRAF^V600E mutation (58% vs. 59%), a higher prevalence of TP53 mutations (17% vs. 1%; p < 0.05), and a worse outcome (structural/biochemical disease: 32% vs. 9%; p < 0.0001).

CONCLUSIONS

HPTC is an aggressive variant, characterized by large tumor size, lymph node involvement, a tendency to metastasize, and a worse outcome.

Noninvasive follicular thyroid neoplasm with papillary-like nuclear features: a review for pathologists

The rising incidence of papillary thyroid carcinoma is linked in part to inclusion of noninvasive follicular variant of papillary thyroid carcinoma. Despite its designation as carcinoma, noninvasive follicular variant of papillary thyroid carcinoma appears to be exceptionally indolent, often over treated by current treatment practices. Additionally, criteria for diagnosis have historically been subjective and challenging. Recently, an international multidisciplinary collaborative group performed a clinicopathologic survey of such cases with extended follow-up and concluded based on the outcome data that a revision in nomenclature was warranted, proposing 'Noninvasive Follicular Thyroid Neoplasm with Papillary-like Nuclear Features (NIFTP).' This monograph is a synopsis and guide for pathologists on NIFTP and focuses on histologic features, including inclusion and exclusion criteria used to define NIFTP, as well as grossing guidelines, reporting practices, and potential diagnostic limitations.

Predicting thyroid nodule malignancy at several prevalence values with a combined Bethesda-molecular test

Investigation of thyroid nodules using fine-needle aspiration cytology (FNAC) gives indeterminate results in up to 30% of samples using the Bethesda System for Reporting Thyroid Cytopathology (TBSRTC). We present a combined Bethesda-molecular predictor of nodule malignancy to improve the accuracy of the preoperative diagnosis of thyroid nodules. To detect a molecular signature of thyroid nodule malignancy, a molecular test was performed on FNACs from 128 thyroid nodules from prospectively included patients, collected in a tertiary center. The test relied on a transcriptomic array of 20 genes selected from a previous study. An optimal set of seven genes was identified using a logistic regression model. Comparison between the combined predictor (TBSRTC + molecular) and TBSRTC alone used the area under the ROC curve (AUC). Performance of the combined predictor was calculated according to various malignancy prevalence values and benefit-to-harm ratios (B/Hr) (favoring sensitivity or specificity). In our population (36% malignancy prevalence) and with a B/Hr of 1, the combined predictor achieved 95% specificity and 76% sensitivity. The AUC was 93.5%; higher than that of TBSRTC (P = 0.004). Among indeterminate nodules (30% malignancy prevalence), sensitivity and specificity were 52.2% and 96.2%, respectively, with a B/Hr of 1, or 95.7% and 64.2% with a B/Hr of 4 (favoring sensitivity), allowing avoidance of 64% of unnecessary surgeries at the cost of only one false-positive result. In conclusion, this predictor could improve the detection of thyroid nodule malignancy, taking into account malignancy prevalence and B/Hr, and reduce the number of unnecessary thyroidectomies.

Follicular morphological characteristics may be associated with invasion in follicular thyroid neoplasms with papillary-like nuclear features

The newly proposed nomenclature and diagnostic criteria for encapsulated follicular variant of papillary thyroid carcinoma (EFVPTC), the noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP), could improve the consistency and accuracy of diagnosing this entity. Diagnosis of NIFTP requires evaluation of the complete tumor border or capsule. The presence of tumor invasion in follicular thyroid neoplasms with papillary-like nuclear features has been recently discussed by many authors. In this study, we examined the predictive value and association of follicular morphological characteristics with the tumor invasion. In addition, we analyzed the association between tumor encapsulation and molecular profile in EFVPTC/NIFTP cases. A total of 106 cases of FVPTC were included in the study. The tumors were grouped based on the presence of tumor capsule and characteristics of tumor border, as 1) completely encapsulated tumors without invasion, 2) encapsulated tumors with invasion, 3) infiltrative tumors without a capsule. Clinicopathological features, histomorphological features [nuclear criteria, minor diagnostic features, follicles oriented perpendicular to tumor border/capsule (FOPBC)] and molecular alterations in BRAF, NRAS, and KRAS genes were evaluated. FOPBC were significantly more frequently seen in encapsulated tumors with invasion (p = 0.008). The nuclear features were not associated with the presence of encapsulation and characteristics of tumor border. BRAF mutation was more frequent in infiltrative tumors, while NRAS mutation was more frequent in encapsulated tumors, but the results were not statistically significant (p = 0.917). In conclusion, FOPBC histomorphological feature may be associated with tumor invasion in EFVPTC/NIFTP. Additionally, BRAF/KRAS/NRAS mutation analysis may prevent inadequate treatment in these patients.

Somatic mutation profiling of hobnail variant of papillary thyroid carcinoma

Hobnail variant of papillary thyroid carcinoma (HPTC) represents a recently described, aggressive and rare group of thyroid tumors with poorly understood pathogenesis. Molecular data about this group of cancers are few, and a more detailed molecular characterization of these tumors is needed. The main objective of the study is to define a comprehensive molecular typing of HPTC. Eighteen patients affected by HPTC, including eighteen primary tumors and four lymph node metastases, were screened for NRAS, KRAS, HRAS, BRAF, TP53, PIK3CA, hTERT, PTEN, CDKN2A, EGFR, AKT1, CTNNB1 and NOTCH1 gene mutations. Sequencing is conducted on the MiSEQ system, and molecular data are compared with clinical-pathologic data and follow-up. The patients include 14 women and 4 men. Ages range from 23 to 87 years. All 18 primary tumors of HPTC showed ≥30% hobnail features. BRAF and TP53 mutations are by far the most common genetic alterations in primary HPTC (72.2% and 55.6%, respectively), followed by hTERT (44.4%), PIK3CA (27.8%), CTNNB1 (16.7%), EGFR (11.1%), AKT1 (5.5%) and NOTCH1 (5.5%). The mutational pattern in primary tumors and metastasis was usually maintained. Univariate Cox regression analyses with bootstrap procedure indicated a significantly increased mortality risk in patients harboring BRAF mutation and BRAF mutation associated with TP53 and/or PIK3CA mutations. The detection of these multiple mutations appears to allow the identification of a subset of more aggressive tumors within the group and to bear information that should be useful for prognostic stratification of these patients including the planning of adjuvant therapy.

Comparing Clinicopathologic and Radiographic Findings Between TT-UMP, Classical, and Non-Encapsulated Follicular Variants of Papillary Thyroid Carcinomas

Thyroid tumors of uncertain malignant potential (TT-UMP) comprise an accepted subgroup of follicular-patterned thyroid tumors for which benignancy or malignancy cannot be precisely assessed. We aimed to evaluate the demographic characteristics, ultrasound (US) findings, and cytological results of patients with TT-UMP and compare these findings to a classical variant of papillary thyroid carcinoma (CV-PTC) and non-encapsulated follicular variant of PTC (NEFV-PTC) patients; we also evaluated the immunohistochemical characteristics of patients with TT-UMP. Twenty-four patients with TT-UMP, 672 with CV-PTC, and 132 with NEFV-PTC were included in the study. Mean longitudinal nodule size and median nodule volume were higher in the TT-UMP group than in the CV-PTC and NEFV-PTC groups (p < 0.001 and p < 0.001 for CV-PTC; p < 0.001 and p = 0.008 for NEFV-PTC). The presence of halo and peripheral vascularization was observed more frequently in the TT-UMP group than in the CV-PTC group (p = 0.002 and p = 0.024). Benign and follicular neoplasm/suspicious for follicular neoplasm cytological results were higher in the TT-UMP group than in the CV-PTC group (p = 0.030 and p = 0.001). US findings were similar between TT-UMP and NEFV-PTC groups (all, p > 0.05). However, none of the patients with TT-UMP were called malignant; 105 patients (31.2 %) of CV-PTC and 11 patients (9.5 %) of NEFV-PTC (infiltrative FV) were classified as malignant cytologically. Tumor size was higher in the TT-UMP group than in the CV-PTC and NEFV-PTC groups (p < 0.001 and p = 0.006). In the TT-UMP group, positive expression of HBME-1, CK-19, and Gal-3 was found in 50, 33.3, and 25 % of patients, respectively. This study demonstrated that none of the TT-UMP patients were evaluated as malignant in preoperative cytology. However, patients with TT-UMP had higher nodule and tumor sizes than CV-PTC and NEFV-PTC patients; US features were similar between NEFV-PTC and TT-UMP patients.

Follicular variant of papillary thyroid cancer in Alström syndrome

Alström syndrome (AS) is an autosomal recessive disorder, characterized by cone-rod dystrophy, sensorineural hearing loss, obesity, hyperinsulinemia with insulin resistance, type 2 diabetes mellitus and progressive pulmonary, hepatic and renal dysfunction. AS is caused by mutations in the ALMS1 gene, located on the short arm of chromosome 2. We report a 35-year-old woman with known history of AS, who developed a follicular variant of papillary thyroid carcinoma. To our knowledge this is the first association of AS with thyroid malignancy, among the approximately 450 cases reported since the first description of the syndrome. We conclude that papillary thyroid carcinoma should be considered in the differential diagnosis of thyroid nodules in patients with AS.

Serum Immunoproteomics Combined With Pathological Reassessment of Surgical Specimens Identifies TCP-1ζ Autoantibody as a Potential Biomarker in Thyroid Neoplasia

CONTEXT

Current methods of preoperative diagnostics frequently fail to discriminate between benign and malignant thyroid neoplasms. In encapsulated follicular-patterned tumors (EnFPT), this discrimination is challenging even using histopathological analysis. Autoantibody response against tumor-associated antigens is a well-documented phenomenon with prominent diagnostic potential; however, autoantigenicity of thyroid tumors remains poorly explored.

OBJECTIVES

Objectives were exploration of tumor-associated antigen repertoire of thyroid tumors and identification of candidate autoantibody biomarkers capable of discrimination between benign and malignant thyroid neoplasms.

DESIGN, SETTING, AND PATIENTS

Proteins isolated from FTC-133 cells were subjected to two-dimensional Western blotting using pooled serum samples of patients originally diagnosed with either papillary thyroid carcinoma (PTC) or EnFPT represented by apparently benign follicular thyroid adenomas, as well as healthy individuals. Immunoreactive proteins were identified using liquid chromatography-tandem mass-spectrometry. Pathological reassessment of EnFPT was performed applying nonconservative criteria for capsular invasion and significance of focal PTC nuclear changes (PTC-NCs). Recombinant T-complex protein 1 subunitζ (TCP-1ζ) was used to examine an expanded serum sample set of patients with various thyroid neoplasms (n = 89) for TCP-1ζ autoantibodies. All patients were included in tertiary referral centers.

RESULTS

A protein demonstrating a distinct pattern of EnFPT-specific seroreactivity was identified as TCP-1ζ protein. A subsequent search for clinicopathological correlates of TCP-1ζ seroreactivity revealed nonclassical capsular invasion or focal PTC-NC in all TCP-1ζ antibody-positive cases. Further studies in an expanded sample set confirmed the specificity of TCP-1ζ autoantibodies to malignant EnFPT.

CONCLUSIONS

We identified TCP-1ζ autoantibodies as a potential biomarker for presurgical discrimination between benign and malignant encapsulated follicular-patterned thyroid tumors. Our results suggest the use of nonconservative morphological criteria for diagnosis of malignant EnFPT in biomarker identification studies and provide a peculiar example of uncovering the diagnostic potential of a candidate biomarker using incorporation of pathological reassessment in the pipeline of immunoproteomic research.

Is an Increase in Thyroid Nodule Volume a Risk Factor for Malignancy?

BACKGROUND

Most benign thyroid nodules found on fine-needle aspiration cytology (FNAC) can be followed with periodic ultrasonography. During follow-up, when nodules grow, re-aspiration or surgical resection for a histologic diagnosis is recommended. However, there is little evidence regarding the malignancy risk associated with nodule growth.

METHOD

We retrospectively reviewed the records of 542 patients with FNAC-diagnosed adenomatous nodules (ANs) who underwent surgery in 2011-2012 at Kuma Hospital. Among them, 196 patients had surgical resection because of nodule volume growth (median, 1.94 times; range, 1.21-27.60) during the observation period (mean, 45.9 months). Excluding nodule growth, the remaining 346 patients underwent surgery for various reasons including the large size of nodules or the appearance of undefined ultrasound features suspicious for malignancy during follow-up. For comparison, we reviewed 409 patients with FNAC-diagnosed follicular neoplasms (FNs) operated on in 2011-2013. Most (n=327) underwent surgery shortly after the FNAC diagnosis, while 82 patients were observed for a period of time and had a late operation due to nodule volume growth (median, 2.70 times; range, 1.27-15.82).

RESULTS

The histologic diagnoses of the 196 growing FNAC-diagnosed ANs were 158 ANs, 32 follicular adenomas (FAs), 4 follicular tumors of uncertain malignant potential (FT-UMP; 2%), and 2 malignancies (1%). The 346 patients who underwent surgery for reasons other than nodular growth had 16 FT-UMP (4.6%) and 16 malignancies (4.6%). This suggests that nodule growth itself is not a risk factor for malignancy. On the other hand, there were 23 FT-UMP (28%) and 15 malignancies (18.3%) in the 82 growing FNAC-diagnosed FNs, while 44 FT-UMP (13.5%) and 54 malignancies (16.5%) in the 327 FNAC-diagnosed FN patients who underwent immediate surgery. The malignant potential was significantly higher in the growing-FN group than the immediate-surgery FN group (p<0.05). No significant difference was found in the volume change between the benign and the FT-UMP plus malignant group in the growing FNs, suggesting that a growth rate does not correlate with malignant potential.

CONCLUSION

This is the first demonstration that the malignancy risk is low in FNAC-diagnosed ANs, even if the nodules grow significantly, whereas FNs have a higher risk when they grow.

BRAF(V600E) Mutation, RET/PTC1 and PAX8-PPAR Gamma Rearrangements in Follicular Epithelium Derived Thyroid Lesions - Institutional Experience and Literature Review

BACKGROUND

Thyroid cancers are the most frequently occurring endocrine malignancy worldwide. In Turkey, thyroid cancers are ranked 2(nd) on the incidence list in women, with a rate of 16.2%, but they are not included among the top 10 cancer types in men.

AIMS

To identify the contribution of the BRAF(V600E) mutation, and the RET/PTC1 and PAX8-PPARγ rearrangements in the diagnosis and differential diagnosis of follicular epithelial-derived thyroid lesions.

STUDY DESIGN

Retrospective clinical and molecular genetic study.

METHODS

A total of 86 thyroid cases diagnosed between 2001 and 2012 at the Department of Pathology were included in the retrospective study group. Samples best representing the lesion and comprising capsules were chosen in the selection of paraffin blocks pertaining to the cases. The BRAF(V600E) mutation, and the RET/PTC1 and PAX8-PPARγ rearrangements were investigated in all cases.

RESULTS

The BRAF(V600E) mutation was observed in 12 out of 37 papillary carcinoma cases (32.4%), in 1 out of 15 follicular carcinoma cases (6.6%), and in 1 out of 7 undifferentiated carcinoma cases (14.3%). No mutation was detected in benign lesions. The RET/PTC1 rearrangement was detected in 2 out of 7 undifferentiated carcinoma cases (28.6%), and in 1 out of 15 follicular carcinoma cases (6.6%). No gene rearrangement was detected in benign lesions. The PAX8-PPARγ rearrangement was detected in 5 out of 15 follicular thyroid carcinoma cases (33.3%) and in 1 out of 15 follicular adenoma cases (6.6%).

CONCLUSION

The BRAF(V600E) mutation and RET/PTC1 rearrangement were effective in distinguishing the follicular epithelium-derived benign and malignant lesions of the thyroid in the resection materials. The BRAF(V600E) mutation was rather specific to papillary carcinoma in the thyroid, and in cases where the BRAF(V600E) mutation was detected, multi-centricity, lymph node metastasis and capsular invasion findings were observed more frequently compared to cases in which no mutation was observed. The PAX8-PPARγ rearrangement was observed to be more effective in the differentiation of adenomas and carcinomas in follicular neoplasms of the thyroid, whereas the RET/PTC1 analysis contributed to the differential diagnosis of papillary carcinoma histogenesis at a frequency of 29% in undifferentiated thyroid carcinomas.

Diagnostic criteria of well differentiated thyroid tumor of uncertain malignant potential; a histomorphological and immunohistochemical appraisal

BACKGROUND

Well differentiated thyroid tumor of uncertain malignant potential (WDT-UMP) represents a true "gray zone" of "follicular patterned" thyroid lesions, that needs to be characterized in order to outright the diagnosis of carcinoma and avoid unnecessary aggressive treatment.

AIM

To emphasize on the histomorphological criteria for more accurate diagnosis of WDT-UMP. Also to compare the immunohistochemical expression of CK19 of WDT-UMP versus adenoma and papillary thyroid carcinoma (PTC).

MATERIALS AND METHODS

The study included 60 thyroid specimens; 18 WDT-UMPs, 24 PTC (18 classic variant and 6 follicular variants) and 18 benign thyroid lesions (8 adenoma, 6 Hashimoto's thyroiditis and 4 hyperplastic nodules). H&E stained sections were assessed according to the published major and minor criteria of malignancy in the thyroid. CK 19 immunostaining was examined and evaluated according to the proportion and intensity scores.

RESULTS

We could detect the absence of nuclear inclusions, presence of characteristic nuclear groove, nuclear clearing, ovoid nuclei, nuclear crowdness, nuclear enlargement and pleomorphism as important reliable features for diagnosis of WDT-UMP with p value (<0.0001 for each). WDT-UMP showed moderate to strong CK 19 immunostaining with proportion scores 3 and 4; an intermediate expression profile; higher than adenoma and less than papillary carcinoma (p<0.0001).

CONCLUSION

The constellations of both major and minor criteria of malignancy are important clues for WDT-UMP diagnosis which could be ascertained by CK 19 immunostaining.

Prognostic classification of thyroid follicular cell tumors using Ki-67 labeling index: risk stratification of thyroid follicular cell carcinomas

This review emphasizes that the so-called high-risk thyroid carcinoma is not a distinct tumor entity, but a group of tumors with different histologies. High-grade histological features, such as tumor necrosis, increased mitoses, and nuclear pleomorphism, together with high Ki-67 labeling index (more than 10%), are good indicators of high-risk thyroid carcinoma and suggest a possible risk for anaplastic transformation. This review proposes the stratification of patients with thyroid carcinoma into low-, moderate-, and high-risk groups based on Ki-67 labeling index, which should be useful for the clinical management of patients, even after initial surgery. Currently, both the aggressive variant of papillary carcinoma and poorly differentiated carcinoma are aggressively treated by a completion of total thyroidectomy with prophylactic lymph node dissection followed by radioactive iodine treatment. Therefore, patients with moderate-risk or high-risk thyroid carcinoma based on Ki-67 labeling index should also be considered candidates for this treatment strategy.

Introducing the reporting system for thyroid fine-needle aspiration cytology according to the new guidelines of the Japan Thyroid Association

The Japan Thyroid Association (JTA) recently published new guidelines for clinical management of thyroid nodules. This paper introduces their diagnostic system for reporting thyroid fine-needle aspiration cytology. There are two points where the new reporting system that differs from existing internationally-accepted ones. The first is the subclassification of the so-called indeterminate category, which is divided into 'follicular neoplasm' and 'others'. The second is the subclassification of follicular neoplasm into 'favor benign', 'borderline' and 'favor malignant'. It is characterized by self-explanatory terminologies as to histological type and probability of malignancy to establish further risk stratification as well as to facilitate communication between clinicians and cytopathologists. The different treatment strategies adopted for thyroid nodules is deeply influenced by the particular diagnostic system used for thyroid cytology. In Western countries all patients with follicular neoplasms are advised to have immediate diagnostic surgery while patients in Japan often undergo further risk stratification without immediate surgery. The JTA diagnostic system of reporting thyroid cytology is designed for further risk stratification of patients with indeterminate cytology. If a surgeon applies diagnostic lobectomy to all patients with follicular neoplasm unselectively, this subclassification of follicular neoplasm has no practical meaning and is unnecessary. Cytological risk stratification of follicular neoplasms is optional and cytopathologists can choose either a simple 6-tier system without stratification of follicular neoplasm or a complicated 8-tier system depending on their experience in thyroid cytology and clinical management.

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

BACKGROUND

The tall cell variant of papillary thyroid carcinoma is an aggressive subtype that generally presents as a large tumor in the advanced stage; however, little is known about the tall cell variant of microcarcinoma (tumors measuring <1 cm). In this study, we compare the tall cell variant of microcarcinoma (microTCV) with classic papillary microcarcinomas to examine the hypothesis that, despite the small size, the microTCV may be more aggressive than the classic papillary microcarcinoma.

METHODS

We identified 27 microTCV patients and compared their clinicopathologic features and BRAF(V600E) mutational status with classic papillary microcarcinomas matched by age and size. The patients with microTCV included 22 women and 5 men aged 33 to 74 years (median age, 56 years). All patients underwent total thyroidectomy; 20 patients had lymph node dissection.

RESULTS

Tumor size in microTCV patients ranged from 2 mm to 10 mm (median, 7 mm). Extrathyroidal extension and lymphovascular invasion were seen in 9 (33%) and 4 (15%) tumors, respectively. Thirteen patients (48%) harbored multifocal papillary carcinomas. Metastasis to central compartment lymph nodes was seen in 8 patients and to lateral cervical nodes in 3 patients. Nine of the 25 patients (36%) presented at an advanced stage (stage III/IVA). The BRAF(V600E) mutation was detected in 25 of 27 tumors (92.6%). In contrast, age- and size-matched classic papillary microcarcinomas (n=26) showed no extrathyroidal extension (p=0.002), lymphovascular invasion in 1, central compartment lymph node metastasis in 2, lateral cervical node metastasis in 1, multifocal tumors in 10 (38.5%), the BRAF(V600E) mutation in 20 (76.9%), and it infrequently presented in stage III/IVA (7.7%, p=0.02).

CONCLUSIONS

The microTCV form is associated with aggressive features at presentation, and it should be differentiated from other papillary thyroid microcarcinomas.

Factors predictive of lymph node metastasis in the follicular variant of papillary thyroid carcinoma

BACKGROUND

The treatment of papillary thyroid carcinomas larger than 1 cm usually consists of total thyroidectomy and central lymph node dissection (LND). In patients with the follicular variant of papillary thyroid carcinoma (FVPTC), preoperative cytology and intraoperative frozen-section analysis cannot always establish the diagnosis. The aim of this study was to evaluate predictive factors for lymph node metastasis in patients with FVPTC and to identify patients who might benefit from LND.

METHODS

The study included patients with FVPTC treated by total thyroidectomy and LND between 2000 and 2010 in four departments. When fewer than six non-involved lymph nodes were removed, the patient was excluded from the analysis.

RESULTS

Some 199 patients were included. The median tumour size was 17 (range 1-85) mm, and tumours were classified as T1a in 28 patients, T1b in 40, T2 in 53, and T3 in 78. Eighty-one patients (40·7 per cent) had lymph node metastasis (51 classified as N1a and 30 as N1b). Four risk factors were predictive of lymph node metastasis in the multivariable analysis: multifocality (odds ratio (OR) 2·36, 95 per cent confidence interval 1·15 to 4·86), angiolymphatic invasion (OR 3·67, 1·01 to 13·36), absence of tumour capsule (OR 3·00, 1·47 to 6·14) and tumour involvement of perithyroid tissue (OR 3·89, 1·85 to 8·18). The rate of lymph node metastasis varied between 14 and 94 per cent depending on the presence of risk factors.

CONCLUSION

The rate of lymph node metastasis in patients with FVPTC varies widely according to the presence or absence of predictive risk factors.

Encapsulated papillary thyroid carcinoma, follicular variant: a misnomer

Papillary thyroid carcinoma (PTC) has long been diagnosed based on its unique nuclear features (PTC-N); however, significant observer discrepancies have been reported in the diagnosis of encapsulated follicular patterned lesions (EnFPLs), because the threshold of PTC-N is subjective. An equivocal PTC-N may often occur in non-invasive EnFPLs and benign/malignant disagreements often create serious problems for patients' treatment. This review collects recent publications focusing on the so-called encapsulated follicular variant of papillary thyroid carcinoma (EnFVPTC) and tries to emphasize problems in the histopathological diagnosis of this spectrum of tumors, which covers encapsulated common-type PTC (EncPTC), EnFVPTC, well-differentiated tumor of uncertain malignant potential (WDT-UMP), follicular adenoma (FA) with equivocal PTC-N and minimally invasive follicular carcinoma (mFTC). We propose that EnFVPTC and other EnFPLs with equivocal PTC-N should be classified into a unified category of borderline malignancy, such as well-differentiated tumor of uncertain behavior (WDT-UB), based on their homogeneous excellent outcome. It is suggested that the unified nomenclature of these lesions may be helpful to reduce significant observer disagreements in diagnosis, because complete agreement in the diagnosis of an EncPTC, EnFVPTC or FA by all pathologists may be not possible for this problematic group of tumors. In conclusion, a malignant diagnosis of EnFVPTC should not be used to cover this spectrum of tumors until uncertainty about the nature of this lesion is settled, whether it is benign, precancerous or malignant.

Use of molecular markers in samples obtained from preoperative aspiration of thyroid

Several experiments have been carried out in order to find molecular markers that increase the diagnose accuracy of the Fine-Needle Aspiration (FNA), especially for thyroid lesions of undetermined significance. The growing number of published experiments on one or more of the different types of markers has started to justify the need to gather the pieces of information as a way to add evidence and guide the development of future research in the area. From the search arguments and criteria previously defined, 95 articles were selected from the electronic databases PUBMED, MEDLINE, SCOPUS and LILACS. From the 36 markers submitted to analysis and identified in preoperative FNA thyroid samples, only 10 (GAL3, CK-19, HBME-1, TPO, CD44, Telomerase, DAP IV, RAS, RET and BRAF) were assessed in more than two investigations, be it either in panel or individually. The minimum, medium and maximum values of sensibility, specificity, positive predictive value, negative predictive value and diagnose accuracy were obtained from the group of investigation, as well as the limitations and advantages of the use of each marker were identified. The BRAF mutation, for its unquestionable specificity, and the GAL3, for its regularity of average results obtained here, found in several locations in the cell as well as out of the cell, suggesting multiple functions of this molecule, were observed as holders of more expressive evidence in the effort of reducing the uncertainty of the diagnose in preoperative FNA of thyroid.

Cytological features of well-differentiated tumors of uncertain malignant potential: Indeterminate cytology and WDT-UMP

The purpose of this study was to clarify the cytopathological features of well-differentiated tumors of uncertain malignant potential (WDT-UMP), a possible borderline lesion of thyroid follicular cell tumor. We analysed the cytopathological findings of fine needle aspiration (FNA) smears from 6 cases histologically diagnosed as WDT-UMP. WDT-UMP, benign and malignant lesions were compared retrospectively and morphologically. No (0%) nuclear pseudoinclusions were found in adenomatous goiter (AG), follicular adenoma (FTA) and WDT-UMP. Nuclear pseudoinclusions were increased in number in papillary thyroid carcinoma (PTC) with indeterminate cytology (0.8%) and PTC with malignant cytology (1.2%). The incidence of nuclear grooves increased gradually from AG/FTA (0%), WDT-UMP (4.5%), PTC with indeterminate cytology (6.2%) and PTC with malignant cytology (6.5%). The nuclear area of WDT-UMP, an average of 40.0 µm(2), was between that for benign AG/FTA and PTC with malignant cytology. The maximum/minimum axis of WDT-UMP (0.934) lied between that of AG/FTA and PTC. The degree of the nuclear circularity of WDT-UMP was less than that for PTC. WDT-UMP belong to indeterminate category between PTC and follicular adenoma morphologically, and this is one of the major reasons why some of PTC can be found in the indeterminate category. Questionable PTC-N including questionable nucler inclusions (artifact vacuole) may be seen in WDT-UMP, but absolute or definite nuclear inclusions with sharp border are not found in our 6 cases. Therefore this group of thyroid tumors (EnFVPTC and WDT-UMP) may be found in indeterminate category more often, because of intermediate nuclear morphology and incomplete nuclear vacuoles.

Mouse models of follicular and papillary thyroid cancer progression

A significant number of well-differentiated thyroid cancers progress or recur, becoming resistant to current therapeutic options. Mouse models recapitulating the genetic and histological features of advanced thyroid cancer have been an invaluable tool to dissect the mechanisms involved in the progression from indolent, well differentiated tumors to aggressive, poorly differentiated carcinomas, and to identify novel therapeutic targets. In this review, we focus on the lessons learned from models of epithelial cell-derived thyroid cancer showing progression from hyperplastic lesions to locally invasive and metastatic carcinomas.