Thyroid gland papillary carcinomas with “micropapillary pattern,” a recently recognized poor prognostic finding: clinicopathologic and survival analysis of 7 cases

Comparison of US-guided thermal ablation and surgery for papillary thyroid cancer: a systematic review and meta-analysis

OBJECTIVE

We conducted the systematic review and meta-analysis to comprehensively compare ablation and surgery in terms of effectiveness, safety and multiple factors affecting life quality of patients with papillary thyroid cancer (PTC).

METHODS

PubMed, Embase, Scopus, Web of Science and EBSCO were searched for relevant studies published between January 1980 and September 2023. Two reviewers independently extracted data according to the PRISMA recommendations and assessed the quality of each study with the Cochrane Risk of Bias Tool. Pooled analyses were performed using random or fixed-effects models, as appropriate.

RESULTS

A total of 4829 patients with PTC from 19 eligible studies were included. Through the meta-analysis, similar tumor progression (OR: 1.07; 95% CI 0.78, 1.48; p = 0.66) and recurrence-free survival (OR: 0.86; 95% CI, 0.55, 1.34; p = 0.50) were found between the patients undergoing ablation and those undergoing surgery. More strikingly, the lower risk of major complications (OR: 0.31; 95% CI 0.24, 0.41; p < 0.001), the shorter hospital stay (MD = 3.67 d; 95% CI, -4.89, -2.44; p < 0.001), the abbreviated procedure time (MD: -66.33 min, 95% CI, -77.08, -55.59; p < 0.001), the less intraoperative blood loss (MD: -27.43 ml, 95% CI, -34.60, -20.27; p < 0.001) and the lower treatment cost (MD: -860.42 USD, 95% CI, -1008.03, -712.81; p < 0.001) were noticed in ablation techniques compared to surgical operation. Thermal ablation has shown multiple advantages by virtue of its percutaneous puncture compared with surgical resection.

CONCLUSION

As an effective, safe, minimally invasive and economical modality, thermal ablation might be a promising alternative to existing PTC management options.

Endocervical adenocarcinoma with a micropapillary component: a clinicopathologic analysis in the setting of current WHO classification

Our study aimed to investigate the clinicopathologic and molecular features of endocervical adenocarcinoma with a micropapillary component (EAC-MP) in the setting of current classification schema. We investigated 26 EAC-MP from consecutive 511 adenocarcinomas. HER2 status was analyzed by immunohistochemistry and fluorescence in situ hybridization. Four cases were performed with targeted next-generation sequencing (NGS). We found that HPV-associated adenocarcinomas (HPVA) with a micropapillary component (HPVA-MP) (n = 12) had a higher frequency of large tumor size (> 2 cm), Silva pattern C (12/12, 100%), invasion of the deep cervical wall (> 2/3) (8/12, 66.7%), lymphovascular space invasion (LVSI) (11/12, 91.7%), lymph node metastasis (4/11, 36.4%), FIGO stage III/IV (4/12, 33.3%), and HER2 amplification (3/12, 25%, P = 0.015), compared to those without (HPVA-NMP (all P < 0.05). HPV-independent adenocarcinomas (HPVI) with a micropapillary component (HPVI-MP) (n = 14) had LVSI more commonly than those without (HPVI-NMP) (P = 0.033). Survival analysis indicated that HPVA-MP was associated with worse overall survival and recurrence-free survival than HPVA-NMP (P < 0.01). Particularly, in patients with Silva pattern C, HPVA-MP appeared to have more adverse clinical outcomes (P < 0.01). No survival differences were found in HPVI-MP versus HPVI-NMP (P > 0.05). NGS identified significant mutations in STK11, TERT, ERBB2, TP53, PIK3CA, ARID1A, and NTRK2. We conclude that the micropapillary structure is an indicator for unfavorable clinical outcomes in HPVA, and can aid in the prognostic stratification of Silva pattern C EAC. The presence of HER2 amplification and specific gene mutations raise the possibility for targeted therapy in the future.

Analyzing the correlation between low proportion of hobnail features in papillary thyroid carcinoma and clinical aggressiveness risk

PURPOSE

Hobnail features may enhance the clinical aggressiveness of papillary thyroid carcinoma (PTC). However, whether a low proportion (<30%) of these features contributes to increased PTC aggressiveness remains unclear. This study investigated whether PTC cases with a low proportion hobnail features (<30%) exhibit clinical invasiveness and pathological features of aggressiveness.

METHODS

Pathological specimens from patients with postoperatively diagnosed PTC were retrospectively analyzed. Among them, 29 PTC cases with a low proportion of hobnail features (<30%) were compared with 173 consecutive classical PTC (cPTC) cases. Data regarding age at presentation, sex, tumor size, number of tumors, and histological characteristics were obtained by reviewing electronic medical records. Postoperative information was obtained during follow-up visits and telephone interviews.

RESULTS

Twenty-nine patients with PTC with a low proportion of hobnail features (<30%) were identified, exhibiting a median age of 34 years. At a median follow-up of 31 (IQR, 23-37) months, two patients had recurrent disease in the PTC with a low proportion of hobnail features (<30%) group, whereas there was no recurrence in the cPTC group. No distant metastasis and postoperative mortality were observed in either group. Compared with the cPTC group, patients with PTC and a low proportion of hobnail features exhibited larger tumor volumes and higher susceptibility to capsular invasion and lymph node metastasis. Tumor size and hobnail features emerged as independent risk factors for lymph node metastasis.

CONCLUSION

PTC with a low proportion hobnail features (<30%) and larger tumor volumes are associated with the occurrence of lymph node metastasis. A low proportion of hobnail features (<30%) in PTC may heighten invasiveness, elevating the risk of recurrence.

Hobnail Papillary Thyroid Carcinoma, A Systematic Review and Meta-Analysis

Although papillary thyroid carcinoma (PTC) is considered to have an excellent prognosis, some recently identified more aggressive variants show reduced overall survival rates. Hobnail PTC (HPTC) was newly recognized as one of these aggressive forms, affecting recurrence, metastasis, and overall survival rates. Herein, we performed a systematic review and meta-analysis of studies including cases or case series with patients with HPTC. Furthermore, we included our individual case series consisting of six patients. The pooled mortality rate in the cohort, consisting of 290 patients, was 3.57 (95% CI 1.67−7.65) per 100 person/years. No sex differences could be observed concerning mortality (p = 0.62), but older age and tumor size significantly affected mortality (p = 0.004 and p = 0.02, respectively). The percentage of hobnail cells did not affect mortality (p = 0.97), neither did the presence of BRAF mutations. Classical characteristics such as the presence of extrathyroidal extension (p = 0.001), distant metastases (p < 0.001), and lymph node metastases (p < 0.001) all had a significant impact on mortality. Thus, HPTC appears to correlate with worse overall survival, and all PTC cases should be carefully assessed for this variant.

The efficacy and safety of microwave ablation versus conventional open surgery for the treatment of papillary thyroid microcarcinoma: a systematic review and meta-analysis

Background

Microwave ablation (MWA) technology has been applied to the treatment of papillary thyroid microcarcinoma (PTMC); however, its use as an alternative to conventional open surgery (OS) remains controversial, because it belongs to non-tumor radical treatment. Our article sought to compare the efficacy and safety of MWA and OS in the treatment of PTMC.

Methods

We searched seven databases for studies evaluating the treatment of patients with PTMC using MWA as intervention group and OS as control group, the main outcome contained intra-operative, post-operative and follow-up outcomes. Review Manager 5.4 was used to estimate the effects of the results of the included articles and Cochrane Risk of Bias 2.0 was used to assess the risk of bias. The data were pooled to calculate the mean differences (MD) with 95% confidence intervals (CIs) for the continuous data and the odds ratio (OR) with 95% CIs for the dichotomous data.

Results

A total of 13 studies, comprising 1,088 and 1,081 patients in the MWA and OS groups, respectively, were identified that compared the results of MWA to OS in the treatment of PTMC. All of the articles were at low risk of bias. There were no differences in terms of the recurrence rate (OR =0.80, 95% CI: 0.37 to 1.77; P=0.59) or lymph node metastasis (OR =0.71, 95% CI: 0.26 to 1.95; P=0.51) between the 2 groups. However, compared to the OS group, the MWA group had a shorter operation time (MD =-44.85, 95% CI: 5.73 to 20.68; P<0.00001), less intra-operative blood loss (MD =-23.37, 95% CI: -29.57 to -17.17; P<0.00001), a smaller surgical incision (MD =-47.04, 95% CI: -81.93 to -12.14; P=0.008), a shorter postoperative hospital stay (MD =-4.19, 95% CI: -5.46 to -2.92; P<0.00001), lower hospitalization expenses (MD =-85.65, 95% CI: -133.86 to -37.45; P<0.00001), and fewer complications (OR =0.23, 95% CI: 0.16 to 0.33; P<0.00001).

Conclusions

This meta-analysis suggests that MWA is better than OS at treating PTMC in terms of both intra-operative and post-operative outcomes. Due to the quality and number of the included studies, the long-term effects and suitability of MWA in the treatment of PTMC need to be further studied.

Papillary thyroid carcinoma with hobnail features showing rapid progression and therapy resistance

BACKGROUND

Hobnail variant of papillary thyroid carcinoma (HVPTC), also designated as a micropapillary variant, is a rare but aggressive variant of PTC, representing <2% of all PTC. It was adopted in the newest World Health Organization classification. HVPTC is strongly associated with higher mortality in comparison to classic PTC and a high propensity for disease progression. This paper aimed to investigate the clinical course, cytological and histopathological features, and mutational profile of the hobnail variant from a unique case.

CASE REPORT

A case of a 38-year-old female patient with HVPTC is presented. Total thyroidectomy with central and bilateral, lateral lymphadenectomy was performed. The clinical course showed aggressive features, as lymph node metastasis and extrathyroidal extension were present at the presentation. Molecular and immunohistochemical features are addressed along with a review of the literature.

DISCUSSION

The cytological examination of FNA was in consonance with published literature. The cells showed hobnail features in several segments of both thyroidal lobes on histological examination. The tumour displayed a typical BRAF mutation and Gly12Ala mutation in the KRAS gene, previously not associated with PTC.

CONCLUSION

We aimed to highlight the aggressive, clinicopathological features of this high-risk variant. We emphasise the need to evaluate suspicious thyroid nodules as an adequate diagnosis can prevent delayed therapy. It directly impacts the tumour's stage and prognosis. In fine-needle aspiration cytology showing papillary architecture carcinomas, HVPTC has to be part of the differential diagnosis.

Hobnail variant of papillary thyroid carcinoma: a systematic review and meta-analysis

OBJECTIVE

The hobnail variant of papillary thyroid carcinoma (HVPTC) has emerged as a rare and aggressive variant of papillary thyroid carcinoma (PTC). We aim to determine the prevalence and clinicopathologic factors of HVPTC.

METHODS

A systematic review of the literature for studies examining HVPTC was performed. Four databases (PubMed, Scopus, OVID, Cochrane library) were queried from inception of databases through March 20th, 2020.

RESULTS

Sixteen studies with 124 cases of HVPTC were included. The mean age for all patients was 52.3 years. HVPTC had a prevalence of 1.08% out of all PTC cases, with a mean tumor size of 3.1 cm. In 62% and 50% of cases, lymphovascular invasion and extrathyroidal extension were present, respectively. Follow-up data, with a mean of 49.9 months, revealed a 66% rate of lymph node metastasis and 23% rate of distant metastasis. Tumors with ≥30% hobnail morphology had a 2.6-fold increased odds of developing lymph node metastasis compared with <30% hobnail morphology, however did not differ in rates of distant metastasis. Patients ≥55 years old had a 4.5-fold increased odds of distant metastasis and a 4.7-fold increased odds of lymphovascular invasion over patients <55.

CONCLUSIONS

High rates of locoregional and distant disease as well as high-risk pathological factors reveal the aggressive nature of HVPTC. Diagnostic criteria regarding percentage of hobnail morphology requires further refinement. Further studies are warranted in order to better understand how recognition of this high-risk variant impacts clinical treatment.

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.

Case report: exceptionally rapid growth character of hobnail variant of papillary thyroid carcinoma: a report of four cases

The newest WHO classification adopts hobnail variant as an aggressive variant of papillary thyroid carcinoma (PTC). We here report four cases (ages 70-76 years, all females) with hobnail variant PTC treated at Kuma Hospital. Their lesions were cytologically diagnosed as PTC before surgery, but not as hobnail variant. All patients underwent a total thyroidectomy with central node dissection, and two patients also underwent therapeutic lateral node dissection. The clinical courses of three of the patients were very eventful. One patient showed recurrence to lymph nodes in the lateral compartment only 5 months after the initial surgery. In the initial surgery, one patient had a 36-mm lymph node metastasis in the lateral compartment, which was diagnosed as hobnail variant on pathology; 9 months post-surgery, metastases to the ipsilateral lateral lymph node, lung, and bone were newly detected. Her lung metastasis grew rapidly; its tumor volume-doubling time was 0.15 years and its tumor-doubling rate was 6.67/year. One patient underwent annual ultrasound examinations as postoperative follow-up after hemithyroidectomy for a benign nodule, but a 35-mm nodule diagnosed as PTC on cytology and lateral node metastases appeared within a short period, and she underwent a second surgery. Both the primary lesion and lymph nodes were diagnosed as hobnail variant by postoperative pathology. Three of the four patients showed exceptionally rapid growth of primary and/or metastatic/recurred lesions, indicating that patients with the hobnail variant should undergo very close and careful post-operative observation.

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.

The evolving concept of aggressive histological variants of differentiated thyroid cancer

It is recommended by current clinical guidelines that pathologists identify and report aggressive histological variants of differentiated thyroid cancer (e.g., tall cell, columnar cell, and hobnail variants of papillary thyroid carcinoma; widely invasive follicular thyroid carcinoma). This review analyzes the historical evolution of these entities and highlights unresolved issues with respect to the diagnostic criteria for these tumors.

Hobnail cells in encapsulated papillary thyroid carcinoma: Report of 2 cases with immunohistochemical and molecular findings and literature analysis

Papillary thyroid carcinoma (PTC) is the most common malignant tumor of the thyroid gland with most tumors behaving in an indolent fashion. However, morphologic variants have been described, such as tall cell, diffuse sclerosing, columnar cell etc. which are biologically more aggressive. One of these variants includes the more recently described hobnail variant (HVPTC) which shows micropapillae and presence of large cells with apically placed hyperchromatic nuclei, reverse polarity, and eosinophilic cytoplasm, akin to hobnail cells. The presence of >30% hobnail cells in a PTC deserves categorization as a hobnail variant. This variant is usually associated with extra thyroidal extension, lymphovascular invasion and lymph node metastasis. We describe the pathologic and molecular features of two cases of encapsulated PTC with hobnail cells in a 68 year old male and a 22 year old female (30% and 10% hobnail cells respectively). Both cases presented as low stage (pT2) tumors and showed no aggressive features like lymph node metastasis, or extrathyroidal extension (ETE) at the time of presentation. Tumors in both cases showed presence of BRAFV600E mutation, absence of RAS and/or TP53 mutations, and were negative for RET and PAX88/PPARG gene rearrangements.

[Histopatological and molecular genetic characteristics of clinically aggressive variants of papillary thyroid carcinoma]

Papillary carcinoma is the most commonly diagnosed form of well-differentiated thyroid cancer that is generally characterized by a favorable prognosis. However, a number of relatively rare variants of this tumor, such as papillary carcinoma of high cells, papillary carcinoma of columnar cells, a diffuse sclerosing variant and recently described cancer of shoe nail cell type, are characterized by a less favorable clinical course, a high frequency of distant metastasis, and relatively low overall and relapse-free survival rates. In this connection, it is important to recognize these options at the stage of a primary morphological study. This review of the literature considers the morphological, clinical and molecular genetic features of the above variants of papillary thyroid carcinoma.

Young age increases the risk of lymph node positivity in papillary thyroid cancer patients: a SEER data-based study

Introduction

Currently in papillary thyroid cancer (PTC), the correlation between lymph node positivity (LN+) and patient's age at diagnosis is still inconclusive. The aim of this study was to investigate whether younger PTC patients had higher LN+ rates.

Patients and methods

From the 1998-2013 Surveillance, Epidemiology, and End Results database, we analyzed PTC patients with at least 1 LN examined. The patients were divided into 5 groups by age separately for each T stage: ≤30; 31-40; 41-50; 51-60; >60 years.

Results

A total of 46,077 PTC patients were identified, including 8,386 (18.2%) patients aged ≤30 years, 10,971 (23.8%) patients aged 31-40 years, 11,646 (25.3%) patients aged 41-50 years, 8,596 (18.7%) patients aged 51-60 years, and 6,478 (14.1%) patients aged >60 years. In each T stage, LN+ rates were inversely associated with age at diagnosis, which was validated by multivariate logistic regression analysis (p<0.001). In addition, the subset of patients 30 or younger had the highest lymph node ratio compared with other subsets (p<0.001).

Conclusion

We identified that younger PTC patients have an increased predisposition for LN+ regardless of T stage. This finding could help surgeons to select the optimal treatment for younger PTC patients.

Aggressive Variants of Papillary Thyroid Carcinoma: Hobnail, Tall Cell, Columnar, and Solid

Papillary thyroid carcinomas are the most common endocrine cancer and are usually associated with good survival. However, some variants of papillary thyroid carcinomas may behave more aggressively than classic papillary thyroid carcinomas. The tall cell variant of papillary thyroid carcinoma is the most common aggressive variant of papillary thyroid carcinoma. The aggressive behavior has been ascribed to the histologic subtype and/or to the clinicopathologic features, an issue that remains controversial. The columnar variant of papillary thyroid carcinoma can be aggressive, particularly in older patients, with larger tumors showing a diffusely infiltrative growth pattern and extrathyroidal extension. A papillary thyroid carcinoma is designated as solid/trabecular variant when all or nearly all of a tumor not belonging to any of the other variants has a solid, trabecular, or nested (insular) appearance. This tumor must be distinguished from poorly differentiated thyroid carcinoma which has the same growth pattern but lacks nuclear features of papillary thyroid carcinoma and may show tumor necrosis and high mitotic activity. New to the fourth edition of the WHO Classification of Tumours of Endocrine Organs, the hobnail variant of papillary thyroid carcinoma is a moderately differentiated papillary thyroid carcinoma variant with aggressive clinical behavior and significant mortality. All of these variants are histologically unique and important to recognize due to their aggressive behavior.

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.

Hobnail Variant of Papillary Thyroid Carcinoma: a Literature Review

Papillary thyroid carcinoma is the most common thyroid malignancy and it is usually associated with a good prognosis. However, recurrence, metastases, and cancer death may occur in 10 to 15% of patients with more aggressive types of papillary thyroid carcinoma, such as tall cell, columnar cell, solid variant, or the more recently described hobnail variant of papillary thyroid carcinoma. Papillary thyroid carcinoma with a prominent hobnail pattern is a moderately differentiated papillary thyroid carcinoma variant with aggressive clinical behavior and significant mortality. The hobnail variant of papillary thyroid carcinoma shows prominent hobnail features, which have also been referred to as micropapillary. The typical hobnail/micropapillary morphological features show loss of cellular polarity/cohesiveness and support an epithelial-mesenchymal transition as a possible mechanism of metastasis. BRAF p.V600E is the most common mutation in papillary thyroid carcinoma, including the hobnail variant; recent and continuing studies are focused on defining other molecular anomalies that may be useful for prognostic stratification and may provide therapeutic targets.

Hobnail variant of papillary thyroid carcinoma: molecular profiling and comparison to classical papillary thyroid carcinoma, poorly differentiated thyroid carcinoma and anaplastic thyroid carcinoma

BACKGROUND

As a rare but aggressive papillary thyroid carcinoma (PTC) variant, the genetic changes of hobnail variant of PTC (HVPTC) are still unclear.

RESULTS

The prevalence of HVPTC was 1.69% (18/1062) of all PTC diagnosed in our cohort. 73 samples from 55 patients (17 HVPTC, 26 CPTC, 7 PDTC and 5 ATC) were successfully analyzed using targeted NGS with an 18-gene panel. Thirty-seven mutation variant types were identified among 11 genes. BRAF V600E mutation was the most common mutation, which is present in almost all HVPTC samples (16/17, 94%), most CPTC samples (20/26, 77%), and none of the ATC and PDTC samples. TERT promoter mutation (C228T) was identified in 2 ATC and one HVPTC patient. RAS and TP53 mutation are almost exclusively present among ATC and PDTC samples although TP53 mutation was also observed in 3 HVPTC patients. Six different GNAS mutations were identified among 8 CPTC patients (31%) and none of the HVPTC patients. The only patient who died of disease progression harbored concomitant TERT C228T mutation, BRAF V600E mutation and TP53 mutation.

METHODS

HVPTC cases were identified from a group of 1062 consecutive surgical specimens diagnosed as PTC between 2000 and 2010. Targeted next-generation sequencing (NGS) was applied to investigate the mutation spectrum of HVPTC, compared to classical PTC (CPTC), poorly differentiated thyroid carcinoma (PDTC) and anaplastic thyroid carcinoma (ATC).

CONCLUSION

As an aggressive variant of PTC, HVPTC has relatively specific molecular features, which is somewhat different from both CPTC and ATC/PDTC and may underlie its relatively aggressive behavior.

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.

The micropapillary/hobnail variant of papillary thyroid carcinoma: A review of series described in the literature compared to a series from one southern Italy pathology institution

Papillary thyroid carcinoma (PTC) has a good prognosis with a 10-yr survival greater than 90%. Recently, a micro-papillary pattern with hobnail appearance (MPHC) in PTC has been indicated as associated with poor prognosis, but this suggestion is based only on a few cases from geographical areas different from ours. Two-hundred ninety-nine consecutive PTC cases were collected between the years of 1992 and 2014 at our institution. The corresponding histologic sections (at least 6 for each case) were stained with hematoxylin and eosin and reviewed independently by two pathologists to reach a consensus on the identification and quantification of the MPHC. As done in other cohorts, parallel serial sections were stained with antisera for thyroglobulin, epithelial membrane antigen, thyroid-transcription-factor-1 and Ki 67. BRAF gene mutation at codon 600 and RET/PTC1 gene rearrangements were searched. A comparative statistical analysis was done between the present series and previously published series. Of the 295 PTC, 124 (42.5%) were follicular, 104 (35%) classic, 34 (11.5%) sclerosing, 15 (5%) tall cells, 10 (3.4%) Warthin-like, and 8 (2.7%) MPHC. Four MHPC cases (50%) harbored the BRAF V600E variant, while one was positive for RET/PTC1 rearrangement. Our rate of MPHC-PTC (2.7%) is 2X to 8X greater than those reported previously for cohorts from North America + North Italy, Korea and Mexico. MPHC prognosis appears to be better compared to other cohorts, probably due to not only to the lower rate of the vascular invasion, but also to the smaller size of the MPHC-PTC nodule.

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.

Hobnail variant of papillary thyroid carcinoma: an institutional case series and molecular profile

BACKGROUND

Papillary thyroid carcinoma (PTC) is increasing in incidence while mortality is unchanged. Identifying patients with higher risk of recurrence and death is essential. Case series identify the hobnail variant of PTC (HVPTC), which is characterized by micropapillary architecture, apocrine features, and loss of cellular polarity. Herein, we describe the clinical course, pathologic features, and mutational profile of patients at our institution with HVPTC.

METHODS

A query into the surgical pathologic database (2009-2012) was performed, and clinicopathologic data were collected on all patients carrying the diagnosis of HVPTC. BRAF(V600E) testing was performed on paraffin-embedded blocks using SNaPshot mutational analysis.

RESULTS

Twelve patients with HVPTC were identified, with an average age of 54.1±18.8 years. Seven patients (63.6%) were AJCC Stage III or IV at presentation. Tumors were large (3.7±2.0 cm), some were multifocal (33.3%), and frequently with extrathyroidal extension (58.3%), lymphovascular invasion (41.7%), and lymph node metastasis (75%). Forty percent of the patients had concomitant tall cell features (TCF), and two had small foci of undifferentiated (anaplastic) thyroid carcinoma (ATC). Eighty percent of tumors undergoing mutational analysis had the BRAF(V600E) mutation, and the remaining 20% harbored a RET/PTC1 gene rearrangement. No other known thyroid cancer mutations were identified on SNaPshot analysis. At median follow-up of 26 months, four patients had recurrent or persistent disease, one of whom died from the disease one year after surgery.

CONCLUSIONS

The hobnail variant of PTC has an aggressive behavior, with a high incidence of infiltrative tumors and metastatic disease. Strikingly, all tumors in our series harbored a PTC-associated genetic abnormality, either a BRAF(V600E) mutation (80%) or a RET/PTC1 rearrangement (20%). This histologic variant warrants further study, and patients with this diagnosis should be observed closely for recurrence.

Napsin A expression in anaplastic, poorly differentiated, and micropapillary pattern thyroid carcinomas

Napsin A is a sensitive and specific marker for pulmonary adenocarcinoma versus squamous cell carcinoma. However, studies have shown that napsin A is also positive in approximately 5% of papillary thyroid carcinomas. The prevalence of napsin A in more aggressive types of thyroid carcinoma is unknown. Napsin A positivity in metastatic thyroid carcinoma, especially in conjunction with thyroid transcription factor-1 (TTF-1), could be misdiagnosed as lung adenocarcinoma. We investigated napsin A, TTF-1, and PAX8 expression in 26 anaplastic, 16 poorly differentiated, and 2 micropapillary pattern thyroid carcinomas. A focal micropapillary component was also present in 3 poorly differentiated and 3 anaplastic thyroid carcinomas. Four of 26 (15%) anaplastic, 2/16 (13%) poorly differentiated, and 2/2 (100%) micropapillary pattern thyroid carcinomas were napsin A positive. Three of the 6 cases (50%) with a focal micropapillary component were napsin A positive (1 of these 3 cases was positive only in the micropapillary component). All napsin A-positive cases were also positive for TTF-1, and all but 1 micropapillary pattern carcinoma were also PAX8 positive. In 1 case, napsin A was positive in the micropapillary component, but PAX8 was only positive in the adjacent poorly differentiated carcinoma. In summary, a minority of anaplastic and poorly differentiated thyroid carcinomas are napsin A positive. More importantly, napsin A expression is more common in carcinomas with a micropapillary component, a pattern shared in common with some lung adenocarcinomas. PAX8 may be diagnostically useful to distinguish these napsin A-positive thyroid carcinomas from lung adenocarcinomas, which are PAX8 negative.