The Long Journey towards Personalized Targeted Therapy in Poorly Differentiated Thyroid Carcinoma (PDTC): A Case Report and Systematic Review

BACKGROUND

Poorly differentiated thyroid carcinoma (PDTC) has an intermediate prognosis between indolent well-differentiated thyroid carcinoma (TC) and anaplastic carcinoma. Herein, we present a case report with a PDTC component, along with a systematic review of the literature.

CASE REPORT

We report a case of a 45-year-old man diagnosed with a PDTC component, along with hobnail and tall-cell variant features positive for BRAFV600E mutation, after a total thyroidectomy and neck dissection. Radioactive iodine (RAI)-131 therapy was applied, but an early recurrence led to complementary surgeries. The anti-Tg rise, the presence of new lymph nodes, and the negative whole-bodyradioiodine scan were suggestive of a radioiodine-resistant tumor. Lenvatinib, sorafenib, dabrafenib/trametinib, cabozantinib and radiotherapy were all administered, controlling the tumor for a period of time before the patient ultimately died post-COVID infection. Systematic Review: We searched PubMed, Scopus, and WebofScience to identify studies reporting clinicopathological characteristics, molecular marker expression, and management of non-anaplastic TC with any proportion of PDTC in adult patients. Of the 2007 records retrieved, 82were included in our review (PROSPERO-ID545847).

CONCLUSIONS

Our case, together with the systematic review, imply that a combination of molecular-targetedtreatments may be safe and effective in patients with RAI-resistantBRAF-mutated advanced PDTC when surgery has failed to control tumor progression.

Columnar Cell Thyroid Carcinoma: A Heterogeneous Entity Demonstrating Overlap Between Papillary Thyroid Carcinoma and Follicular Neoplasms

BACKGROUND

Columnar cell papillary thyroid carcinoma (CC-PTC) is a morphologic subtype of papillary thyroid carcinoma with a variable prognosis. It is characterized by neoplastic thyroid follicular-derived cells with pseudostratified columnar morphology arranged in papillary or follicular structures with supranuclear or subnuclear vacuoles. The molecular profile of this subtype has only recently come under scrutiny, with mixed results. The aim of this study is to further explore the morphologic, immunohistochemical, and genetic profile of CC-PTC, as well as to correlate these features with clinical outcomes.

METHODS

CC-PTC cases were identified from 3 institutions. Immunohistochemistry (ER, CDX2) and molecular testing (DNA and RNA sequencing) were performed. Clinicopathologic parameters and patient outcomes were recorded.

RESULTS

Twelve cases (2006-2023) were identified, all in adults (age 45-91). Two presented with disease outside the thyroid gland (neck and mediastinum) and two presented with distant metastasis. Four were high-grade differentiated thyroid carcinomas (necrosis or mitoses), one of which died of disease. Four were noninvasive or minimally invasive, one of which locally recurred. Three patients had lymph node metastases. ER and CDX2 were positive in 73% and 50%, respectively. Pathogenic mutations were found in TERT promoter (n = 3), RAS (n = 2), ATM, NOTCH1, APC, and ESR1, along with cases bearing AGK::BRAF fusion (n = 1), BRAF VE1 expression (n = 1), and NF2 loss (n = 1).

CONCLUSIONS

This study represents the largest molecularly defined cohort of non-oncocytic thyroid carcinomas with columnar cell morphology. These tumors represent a genetically and behaviorally heterogeneous group of neoplasms, some of which have RAS-like or follicular neoplasm-like genetics, some of which have BRAF-p.V600E-like or classic papillary thyroid carcinoma-like genetics, and some of which remain unclear. Noninvasive or minimally invasive tumors showed an indolent course compared to those with angioinvasion, gross extrathyroidal growth, or high-grade morphology. Consideration could be given to reclassification of this neoplasm outside of the subtyping of papillary thyroid carcinoma in light of its genetic diversity, distinct morphology, and clinical behavior more closely aligned with follicular thyroid neoplasms.

Management of aggressive variants of papillary thyroid cancer

PURPOSE OF REVIEW

The aim of this study was to provide a timely and relevant review of the latest findings and explore appropriate management of aggressive variants of papillary thyroid cancer (AVPTC).

RECENT FINDINGS

In general, AVPTCs tend to exhibit more invasive characteristics, a lack of responsiveness to radioiodine, increased occurrences of regional spreading, distant metastases and higher mortality rates. Meanwhile, each variant showcases unique clinical and molecular profiles.

SUMMARY

Given the elevated risk of recurrence postsurgery, a more aggressive strategy may be necessary when suspected preoperatively, particularly for those presenting with invasive features. Decision on the extent of surgical treatment and adjuvant therapy is individualized and made by experienced clinicians and multidisciplinary teams based on the clinical presentation, presence of aggressive features and molecular profile. Future studies on development of personalized medicine and molecular target therapy may offer tailored treatment options.

Prognostic scoring system for surgical treatment of intramedullary spinal cord metastases

Although rare, intramedullary spinal cord metastases (ISCMs) are on the rise, most likely due to prolonged survival and improved outcomes as a result of the advances in cancer treatment for cancer patients. While the management of these lesions remains controversial, surgery for ISCM has recently been advocated for selected patients. We performed a retrospective analysis on 30 patients who were surgically treated for intramedullary spinal cord metastases in order to determine a preoperative prognostic scoring system to guide patient selection for surgical interventions. The scoring system was designed to decide between surgery or other therapeutic procedures. The five parameters selected and employed in the assessment system were: 1) patient's general condition, 2) age, 3) primary site of the cancer, 4) number of other extramedullary metastases and 5) severity of neurologic symptoms. Prognosis could not be predicted from a single parameter. These five factors were added together to give a prognostic score between 1 and 10. The average survival period of patients with a prognostic score between 1 and 3 points was 3 months; 11 patients with a score of 4 and 5 points had a mean survival of 7.63 months, while patients with a prognostic score between 6 and 10 was 14.8 months. According to our prognostic scoring system for surgical treatment of ISCM, surgery should be performed in those patients who score above 6 points, while radiotherapy/chemotherapy or palliative care is recommended for those who score between 1 and 3 points. A prognostic score of 4 and 5 represents a grey area where surgeons must use their judgment on whether to intervene either medically or surgically. This scoring system could facilitate decision-making in the management of patients with intramedullary spinal cord metastases.

Aggressive subtypes of papillary thyroid carcinoma smaller than 1 cm

PURPOSE

Tumor size is important in determining the range of surgery in papillary thyroid carcinomas (PTCs), especially those smaller than 1 cm. We aimed to analyze the features of small PTCs with aggressive subtypes based on histological characteristics.

METHODS

In this retrospective study, we reviewed the medical records of 11,570 patients with PTCs ≤ 1 cm who underwent thyroidectomy between January 2009 and December 2016. Aggressive subtypes included diffuse sclerosing, solid, tall cell, columnar cell, and hobnail subtypes.

RESULTS

Among the 11,570 patients with PTCs ≤ 1 cm, 177 aggressive PTC subtypes were identified. Propensity score matching revealed 110 tumors (62.1%) with extrathyroidal extension of aggressive PTC subtypes and 451 (51.1%) non-aggressive PTC subtypes (95% confidence interval [CI], 0.41-0.80, P < 0.001). Metastatic central and lateral neck lymph nodes constituted 3.06 ± 3.67 and 3.81 ± 5.39 of aggressive PTC subtypes and 1.22 ± 2.14 and 2.85 ± 3.79 of non-aggressive PTC subtypes, respectively (central neck nodes: 95% CI, 1.42-2.26, P < 0.001; lateral neck nodes: 95% CI, 2.9-5.90, P < 0.001). Seven patients with aggressive PTC subtypes (3.95%) and 12 with non-aggressive PTC subtypes (1.7%) exhibited recurrence.

CONCLUSION

Aggressive subtypes of small PTC tumors ≤ 1 cm exhibited more extrathyroidal extension and neck node metastasis. This study suggests that surgeons should consider the aggressive subtypes as important factors when deciding the range of surgery in PTCs smaller than 1 cm.

Aggressive variants of follicular cell-derived thyroid carcinoma: an overview

PURPOSE

The incidence of thyroid carcinoma has increased globally in the past years. Papillary thyroid carcinoma (PTC) is the most frequent neoplasm of the thyroid gland comprehending the 90% of the thyroid carcinoma and has an indolent clinical behaviour. However, some variants of follicular cell-derived thyroid carcinoma, including variants of classic of PTC, have been identified that show a more aggressive biological behaviour. An accurate diagnosis of these entities is crucial for planning a more aggressive treatment and improving patients' prognosis of patients. The aim of this review is to present the main clinical, histological, and molecular features of aggressive variants of follicular cell-derived thyroid carcinoma, and to provide useful histological parameters for determining the most suitable therapeutic strategy for patients affected by these forms.

RESULTS

Variants of classic PTC such as the diffuse sclerosing variant (DSV), the tall cell variant (TCV), the columnar cell variant (CCV), the solid/trabecular variant (STV) and the hobnail variant (HV), and other variants of follicular cell-derived thyroid carcinoma, such as poorly differentiated thyroid carcinoma (PDTC), and anaplastic thyroid carcinoma (ATC), are associated with aggressive behaviour.

CONCLUSIONS

The correct identification and diagnosis of aggressive variants of follicular cell-derived thyroid carcinoma is important, as they allow the clinician to adopt the most refined therapeutic strategies in order to the survival of the patients.

Predictive Factors Indicative of Hemithyroidectomy and Close Follow-Up versus Bilateral Total Thyroidectomy for Aggressive Variants of Papillary Thyroid Cancer

Simple Summary

This study evaluated the need for additional surgical treatment in patients diagnosed with aggressive variants of papillary thyroid cancer after lobectomy. With the increase in the frequency of early diagnosis, the detection of papillary thyroid cancer pathologically belonging to the aggressive variant is also increasing. Therefore, there is growing concern regarding the aggressive treatment of encapsulated aggressive variants of papillary thyroid cancer without invasive features. We suggest that close follow-up can be performed without any additional surgical treatment in patients with low-risk aggressive variants of papillary thyroid cancer incidentally detected after hemithyroidectomy. The patients should be provided sufficient consultation with clinicians.

Abstract

The diagnostic and treatment rates of early thyroid cancer have been increasing, including those of aggressive variants of papillary thyroid cancer (AVPTC). This study aimed to analyze the need for completion total thyroidectomy after lobectomy for clinically low-to-intermediate-risk AVPTC. Overall, 249 patients who underwent hemithyroidectomy (HT, n = 46) or bilateral total thyroidectomy (BTT, n = 203) for AVPTC between November 2005 and December 2019 at our single institution were examined. The average follow-up period was 14.9 years, with a recurrence rate of 4.3% and 10.8% in the HT and BTT groups, respectively. Multivariate Cox analysis revealed that palpable tumor on the neck during evaluation (HR, 2.7; 95% CI, 1.1–6.4; p = 0.025), clinical N1b (HR, 8.3; 95% CI, 1.1–63.4; p = 0.041), tumor size (cm) (HR, 1.3; 95% CI, 1.0–1.7; p = 0.036), gross extrathyroidal extension (HR, 3.1; 95% CI, 1.4–7.0; p = 0.007), and pathologic T3b (HR, 3.4; 95% CI, 1.0–11.4; p = 0.045) or T4a (HR, 6.0; 95% CI, 1.9–18.8; p = 0.002) were associated with an increased risk of recurrence. Incidentalomas identified during diagnosis had a significantly lower risk of recurrence (HR, 0.4; 95% CI, 0.2–0.9; p = 0.033). Close follow-up may be performed without completion total thyroidectomy for AVPTC found incidentally after HT.

Papillary Thyroid Carcinoma with High-Grade Features Versus Poorly Differentiated Thyroid Carcinoma: An Analysis of Clinicopathologic and Molecular Features and Outcome

Background: Similar to poorly differentiated thyroid carcinoma (PDTC), papillary thyroid carcinoma with high-grade features (PTC HGF) demonstrates increased mitotic activity and/or necrosis; however, PTC HGF is excluded from the World Health Organization (WHO) definition of PDTC based on maintained nuclear features of PTC. Methods: Consecutive tumors that met criteria for PTC HGF, defined as tumors with maintained nuclear features of PTC and mitoses numbering 5 or more per 10 contiguous high-power fields and/or tumor necrosis, and PDTC (defined as per the WHO criteria) were identified. Clinicopathologic characteristics, follow-up data, and targeted next-generation sequencing results were compared between groups. Results: There were 15 PTC HGF and 47 PDTC. PTC HGF was associated with a higher rate of pT4 disease (53% vs. 13%, p = 0.0027) and lymph node metastases (73% vs. 38%, p = 0.049). The disease-specific survival was worse for patients with PTC HGF compared with those with PDTC using Kaplan-Meier estimation (p < 0.001) and was worse in subgroup analysis evaluating patients with widely invasive PDTC (i.e., those with a similar rate of pT4 disease) and PTC HGF (p = 0.040). PTC HGF had a higher BRAF^V600E mutation rate (42% vs. 3%; p = 0.003), a trend toward more gene fusions (25% vs. 3%; p = 0.052), and a higher rate of relative gain of 1q (67% vs. 15%; p = 0.002) than PDTC. Conclusions: Our results demonstrate that PTC HGF are important to recognize based on their aggressive behavior. The molecular differences between PTC HGF and PDTC suggest that PTC HGF should be considered a distinct group from PDTC.

Genomic profile of columnar cell variant of papillary thyroid carcinoma

BACKGROUND AND AIMS

Columnar cell variant (CCV) is a rare papillary thyroid carcinoma subtype. The majority of CCV occur in older patients and are large, invasive tumours that pursue an aggressive clinical course. Rare well-circumscribed CCV occur in younger female patients and are comparatively indolent.

METHODS AND RESULTS

We retrospectively identified CCV with material available to perform targeted next-generation sequencing and correlated molecular results with clinicopathological features and outcome. Our cohort was comprised of nine CCV. Nearly all were aggressive tumours; however, one was predominantly well-circumscribed and arose in a thyroglossal duct cyst of a 26-year-old woman who had no evidence of disease at last follow-up. Seven (78%) cases demonstrated activating oncogenic driver alterations in BRAF, including BRAF V600E, an activating N486_P490del deletion, and BRAF-AGK fusions. Activating RAS mutations were seen in two (22%) cases. Additionally, three (33%) cases had TERT promoter mutations, four (44%) had loss of the tumour suppressor CDKN2A and one (11%) case had a loss of function TP53 mutation. Most cases (89%) also demonstrated copy number alterations, including recurrent gain of chromosome 1q (five cases) and losses of chromosome 9p (three cases) and 22q (four cases). The one case without secondary pathogenic mutations or copy number alterations was the tumour in the 26-year-old woman.

CONCLUSIONS

We found that CCV is primarily a BRAF-driven tumour, with most also harbouring secondary oncogenic mutations and multiple chromosomal gains and losses. Moreover, our findings suggest that molecular analysis could potentially be used to help risk stratify CCV.

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.

Surgical treatment of intramedullary spinal cord metastases: functional outcome and complications-a multicenter study

Intramedullary spinal cord metastasis (ISCM) is a rare event in the course of advanced malignancy. Management of these lesions remains controversial. Recently, surgery for ISCM has been advocated for selected patients. We performed a retrospective analysis of the clinical course, complications, and outcome of 30 patients surgically treated for ISCM. Patients' age, histopathological diagnoses of primary cancer, tumor size, spinal location, and extramedullary tumor dissemination were collected. Preoperative functional status, pre- and postoperative neurological status, and extent of the tumor resection were also analyzed. Predominant tumor location was thoracic, followed by cervical and conus medullaris. Lung cancer constituted the majority of primary malignancies. In 9 cases, one of the indications for spinal surgery was to obtain a histopathological diagnosis. On admission, all patients presented with neurological symptoms suggestive of myelopathy. After surgery, 18 patients exhibited improvement of symptoms in terms of pain relief and partial recovery of motor and/or sensory deficits; 6 patients were unchanged, while 6 patients exhibited postoperative deterioration. Median survival time after surgery was 9.9 months. Age > 70 years old, presence of systemic metastases, preoperative neurological non functional status, and lung cancer as primary tumor were all factors associated with a worse survival prognosis. This study did not show a clear survival difference between gross total and subtotal ISCM tumor resection. Patients who underwent gross total resection had a worse functional outcome with respect to patients with only partial resection. Gross total resection with low morbidity must be the surgical target, but when not possible, subtotal resection and adjuvant therapy are a valid therapeutic option.

Tall Cell Variant versus Conventional Papillary Thyroid Carcinoma: A Retrospective Analysis in 351 Consecutive Patients

Background: The aim of this retrospective study was to investigate clinical and pathological characteristics of the tall cell variant of papillary thyroid carcinoma compared to conventional variants. Methods: The clinical records of patients who underwent surgical treatment between 2009 and 2015 were analyzed. The patients were divided into two groups: those with a histopathological diagnosis of tall cell papillary carcinoma were included in Group A, and those with a diagnosis of conventional variants in Group B. Results: A total of 35 patients were included in Group A and 316 in Group B. All patients underwent total thyroidectomy. Central compartment and lateral cervical lymph node dissection were performed more frequently in Group A (42.8% vs. 18%, p = 0.001, and 17.1% vs. 6.9%, p = 0.04). Angiolymphatic invasion, parenchymal invasion, extrathyroidal extension, and lymph node metastases were more frequent in Group A, and the data reached statistical significance. Local recurrence was more frequent in Group A (17.1% vs. 6.3%, p = 0.02), with two patients (5.7%) in Group A showing visceral metastases, whereas no patient in Group B developed metastatic cancer (p = 0.009). Conclusions: Tall cell papillary carcinoma is the most frequent aggressive variant of papillary thyroid cancer. Tall cell histology represents an independent poor prognostic factor compared to conventional variants.

Challenges in the Correct Assessment of a Case of Aggressive Thyroid Carcinoma with Synchronous Breast Cancer: A Case Report and Review of the Literature of Essential Role of Radiopharmaceuticals

Thyroid carcinoma represents a complex pathology that can still be considered a medical challenge, despite having a better prognosis and life expectancy than most other neoplasms; also the scenario of multiple malignancies involving thyroid cancer is nowadays a common reality.

MATERIALS AND METHODS

We reviewed the literature regarding the aggressive presentation of synchronous thyroid and breast cancer. In the current paper, we report the case of a 59 years-old woman, diagnosed with invasive ductal breast carcinoma and papillary thyroid carcinoma, presenting a natural history of both aggressive synchronous tumors. At the moment of hospitalization, the diagnosis was breast carcinoma with multiple secondary lesions, suggestive of lung and bone metastases, and nodular goiter.

RESULTS

Searching the literature in PUBMED with the terms "thyroid carcinoma and synchronous breast carcinoma, we found 86 studies; introducing the term "aggressive," the result included 4 studies, among which, none showed to be relevant to the terms aggressive and synchronous. A similar search was done in SCOPUS finding 92 documents and after introducing the term aggressive, the number of papers was 8, none including the literature on synchronous aggressive metastatic thyroid and breast carcinoma. A majority of imaging diagnostic tools were used in this particular medical case in order to ensure the best potential outcome. The final diagnosis was papillary thyroid carcinoma with lung and unusual multiple bone metastases and synchronous invasive ductal breast carcinoma with subcutaneous metastases.

CONCLUSION

The case illustrates the challenges in the correct assessment of oncologic patients, despite the advances in medical imaging and technologies and underlines the essential role of nuclear medicine procedures in the diagnostic and therapy protocols.

Papillary Thyroid Cancer-Aggressive Variants and Impact on Management: A Narrative Review

Introduction

Aggressive variants of papillary thyroid cancer (PTC) have been described with increasing frequency. These variants include diffuse sclerosing variant, tall cell variant, columnar cell variant, solid variant, and hobnail variant.

Methods

We have performed a review of the more aggressive variants of PTC with respect to main characteristics, histological and molecular features, and the consequences that the knowledge of these variants should have in the treatment of the patients.

Results

At the present time, we do not know the prognostic value of these aggressive PTC variants. The extent of the surgical treatment and adjuvant therapy necessary should be decided on the basis of the extent of the tumor at presentation and the opinion of experienced clinicians.

Conclusion

These aggressive variants should be known by clinicians, to avoid underdiagnosis, and treated according to the latest recommendations in the literature.

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.

Thyroid Tumors You Don't Want to Miss

This article examines more uncommon thyroid entities, including anaplastic thyroid carcinoma, poorly differentiated thyroid carcinoma, rare papillary thyroid carcinoma variants, medullary thyroid carcinoma, non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP), and multiple adenomatous nodules in the setting of Cowden syndrome. These entities were chosen based on their clinical significance and because they can be diagnostically challenging due to their morphologic diversity and overlap with other thyroid tumors. This article addresses the diagnostic features of each entity, focusing on how to avoid potential pitfalls and mimics while also highlighting the clinical implications of each diagnosis.

Does Aggressive Variant Histology Without Invasive Features Predict Overall Survival in Papillary Thyroid Cancer?: A National Cancer Database Analysis

OBJECTIVE

We aimed to clarify whether aggressive histology of papillary thyroid cancer (PTC) impacts overall survival (OS).

SUMMARY BACKGROUND DATA

Aggressive variants of PTC (AVPTC) are associated with invasive features. However, their behavior in the absence of these features is not well characterized.

METHODS

Patients treated from 2004 to 2015 for classic PTC (cPTC) or AVPTCs were identified from the National Cancer Database. Patients were further stratified based on presence of at least 1 invasive feature-extrathyroidal extension, multifocality, lymphovascular invasion, nodal or distant metastasis. Demographics, treatments, and OS were compared.

RESULTS

A total of 170,778 patients were included-162,827 cPTC and 7951 AVPTC. Invasive features were more prevalent in AVPTC lesions compared to cPTC (70.7% vs 59.7%, P < 0.001). AVPTC included tall cell/columnar cell (89.5%) and diffuse sclerosing (10.5%) variants. Patients with invasive features had worse OS irrespective of histology. Furthermore, when controlling for demographics, tumor size, and treatment variables in patients with noninvasive lesions, AVPTC histology alone was not associated with worse OS compared to cPTC (P = 0.209). In contrast, among patients who had at least 1 invasive feature, AVPTC histology was independently predictive of worse OS (P < 0.05) {TCV/Columnar hazard ratio [HR] 1.2; [95% confidence interval (CI) 1.1-1.3] and diffuse sclerosing HR 1.3; 95% CI 1.0-1.7]}. All invasive features, except multifocality, were independently associated with worse OS, with metastasis being the most predictive [HR 2.9 (95% CI 2.6-3.2) P < 0.001].

CONCLUSIONS

In the absence of invasive features, AVPTC histology has similar OS compared to cPTC. In contrast, diffuse sclerosing and tall cell/columnar variants are associated with worse OS when invasive features are present.

Cytologic features of aggressive variants of follicular-derived thyroid carcinoma

Certain carcinomas of the thyroid gland behave aggressively resulting in increased patient morbidity and poor patient prognosis. The diagnosis of these aggressive thyroid cancer subtypes is sometimes challenging and subject to increased interobserver variability. This review deals with the cytological features of such tumors including aggressive variants of papillary thyroid carcinoma, poorly differentiated thyroid carcinoma, and anaplastic thyroid carcinoma. These malignancies fall into 2 groups based on their cytomorphology: those that exhibit distinct microscopic features (eg, nuclear findings typical of classical papillary thyroid carcinoma or marked anaplasia) and those that present with more subtle cytologic features (eg, nuclear pseudostratification, "soap bubble" nuclei, supranuclear or subnuclear cytoplasmic vacuoles, rosette-like structures, hobnail cells). We review the literature regarding these aggressive thyroid cancers and highlight important phenotypic characteristics that can be useful for their diagnosis based on fine needle aspiration.

The Current Histologic Classification of Thyroid Cancer

Thyroid cancers of follicular cell derivation provide excellent phenotype-genotype correlations. Current morphologic classifications are complex and require simplification. Benign adenomas have follicular or papillary architecture and bland cytology. Well-differentiated thyroid carcinomas exhibit follicular architecture, expansile growth, and variable cytologic atypia and invasiveness; low-risk tumors have excellent prognosis after surgical resection whereas widely-invasive and angioinvasive tumors warrant total thyroidectomy and radioablation. Papillary carcinoma is less differentiated; indolent microcarcinomas can be managed by active surveillance, whereas clinical lesions with local or distant spread require therapy. Progression gives rise to poorly differentiated and anaplastic carcinomas that are less common but far more aggressive.

Clinically Relevant Prognostic Parameters in Differentiated Thyroid Carcinoma

Although differentiated thyroid carcinomas typically pursue an indolent clinical course, it is important to identify the subset of tumors that are most likely to behave aggressively so that patients with these tumors are counseled and treated appropriately. Extent of disease is fundamental to the prognostication for differentiated thyroid carcinoma; however, there are additional histologic features of the tumor separate from extent of disease that have been shown to affect clinical course. This review will start with a discussion of aggressive variants of papillary thyroid carcinoma, move to the prognostic significance of vascular invasion in follicular thyroid carcinoma, and finish with a discussion of Hürthle cell carcinoma, with an emphasis on why it is not considered a subtype of follicular thyroid carcinoma in the 2017 WHO Classification of Tumors of Endocrine Organs.

Survival of aggressive variants of papillary thyroid carcinoma in patients under 55 years old: a SEER population-based retrospective analysis

BACKGROUND

Patients younger than 55 years of age with papillary thyroid carcinoma (PTC) have excellent survival. Diffuse sclerosing variant (DSV) and tall cell variant (TCV) of PTC are associated with aggressiveness; the survival of patients <55 years of age with these variants is still unclear. We aim to investigate the clinicopathological features and survival of these variants in the age group <55 years.

METHODS

All adult patients (<55 years old) with DSV, TCV and conventional PTC (CPTC) came from the Surveillance, Epidemiology, and End Results program (1988-2013). Kaplan-Meier method and log-rank test were used to analyze the survival. Prognostic factors associated with survival were analyzed by Cox multivariate regression.

RESULTS

There were 280 DSV, 615 TCV, and 56287 CPTC in the age group <55 years. DSV and TCV were associated with multifocality, extrathyroidal extension, lymph node and distant metastasis (all p < 0.05). The 10-year disease-specific survival (DSS) of TCV was worse than CPTC (96.3 vs. 99.4%, p < 0.01), but there was no significant difference between DSV and CPTC (99.5 vs. 99.4%, p > 0.05). Cox multivariate regression showed TCV was the independent predictor of DSS (HR: 5.39, p < 0.01).

CONCLUSION

In the age group <55 years, DSV and TCV are more likely to exhibit aggressive characteristics than CPTC. Patient <55 years of age with DSV have excellent survival likewise, while patients <55 years of age with TCV carry worse survival. Further investigation for the recurrence risk of patients <55 years with these variants would contribute to optimal clinical management making.

Do aggressive variants of papillary thyroid carcinoma have worse clinical outcome than classic papillary thyroid carcinoma?

OBJECTIVE

Evidence for unfavorable outcomes of each type of aggressive variant papillary thyroid carcinoma (AV-PTC) is not clear because most previous studies are focused on tall cell variant (TCV) and did not control for other major confounding factors contributing to clinical outcomes.

DESIGN

Retrospective cohort study.

METHODS

This study included 763 patients with classical PTC (cPTC) and 144 with AV-PTC, including TCV, columnar cell variant (CCV) and hobnail variants. Disease-free survival (DFS) and dynamic risk stratification (DRS) were compared after two-to-one propensity score matching by age, sex, tumor size, lymph node metastasis and extrathyroidal extension.

RESULTS

The AV-PTC group had significantly lower DFS rates than its matched cPTC group (HR = 2.16, 95% CI: 1.12-4.16, P = 0.018). When TCV and CCV were evaluated separately, there was no significant differences in DFS and DRS between patients with TCV (n = 121) and matched cPTC. However, CCV group (n = 18) had significantly poorer DFS than matched cPTC group (HR = 12.19, 95% CI: 2.11-70.33, P = 0.005). In DRS, there were significantly more patients with structural incomplete responses in CCV group compared by matched cPTC group (P = 0.047). CCV was an independent risk factor for structural persistent/recurrent disease in multivariate analysis (HR = 4.28; 95% CI: 1.66-11.00, P = 0.001).

CONCLUSIONS

When other clinicopathological factors were similar, patients with TCV did not exhibit unfavorable clinical outcome, whereas those with CCV had significantly poorer clinical outcome. Individualized therapeutic approach might be necessary for each type of AV-PTCs.

Special types of thyroid carcinoma

This article reviews the small percentage of thyroid tumours that are not classified as classic papillary thyroid carcinoma, follicular thyroid carcinoma, and medullary thyroid carcinoma. It includes subtypes of papillary thyroid carcinoma, including, tall-cell, hobnail/micropapillary, columnar cell, diffuse sclerosing and solid variants. Poorly differentiated carcinoma, high-grade carcinoma and anaplastic thyroid carcinoma are reviewed. Also discussed are entities that are unusual but need to be recognized as primary thyroid neoplasms, i.e. mucoepidermoid carcinoma, sclerosing mucoepidermoid carcinoma with eosinophilia, and mammary analogue secretory carcinoma/secretory carcinoma. The pathological features and prognostic factors are described; a brief review of molecular correlates of these neoplasms is included.

Columnar Cell Variant of Papillary Thyroid Carcinoma: Ultrasonographic and Clinical Differentiation between the Indolent and Aggressive Types

Objective

To evaluate the ultrasonography (US) features and clinical characteristics of columnar cell variant of papillary thyroid carcinoma (CCV-PTC) that can predict disease progression.

Materials and Methods

Six cases of CCV-PTC were identified via surgical pathology analysis at our institution from 1994 to 2016. The histological, architectural, and cytological features met the diagnostic criteria of CCV-PTC. We reviewed the US features and clinicopathological findings in the six cases.

Results

An indolent clinical course was observed in four young female patients aged 27–34 years (median: 32 years), while two older patients aged 55 years or 70 years had an aggressive clinical course. All patients underwent total thyroidectomy and radioiodine therapy. The indolent group included patients with T1 and nodal metastasis, where the disease was not observed during the follow-up period (range: 8–17 years). On the other hand, a larger tumor size (1.8 cm and 6.0 cm), gross extrathyroidal extension to the muscle and lymph node, and distant metastasis were observed in the aggressive group. In one male patient, recurrence occurred immediately after operation, and this patient died 4 years after the diagnosis of thyroid cancer. Based on US, the individuals from the indolent group had a smooth margin, except for one. Both cases in the aggressive group had a microlobulated margin.

Conclusion

Favorable prognosis in CCV-PTC is observed in young patients with T1 staging and demonstrates a smooth margin at US. These US findings might help exclude the same treatment as the aggressive type in the indolent type of CCV-PTC.

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.

Intramedullary spinal cord metastasis from thyroid carcinoma: Case report and a systematic pooled analysis of the literature

Intramedullary spinal cord metastasis (ISCM) is rare and occurs most commonly in the setting of advanced malignancy. The optimal management pathways are not well defined and treatment outcomes from contemporary therapies remain variable. We report a case of a 49-year-old woman with known primary papillary thyroid carcinoma, who presented with rapidly progressive clinical features of Brown-Sequard syndrome. A detailed pooled analysis of the literature was conducted to characterise the clinical and demographic features, management options, and expected survival outcomes for cases of ISCM. We secondarily performed a subgroup analysis on the incidence, clinical and management characteristics of thyroid carcinoma ISCM.

"Noninvasive Follicular Thyroid Neoplasm With Papillary-Like Nuclear Features" With Focal Spindle Cell Metaplasia

"Noninvasive follicular thyroid neoplasm with papillary-like nuclear features" (NIFTP) is a recent reclassification of the encapsulated follicular variant of papillary thyroid carcinoma, which is supposed to reflect its indolent clinical behavior and to prevent overtreatment of patients with this neoplasm. The diagnosis of NIFTP can only be made histologically on the surgical specimen according to specific inclusion and exclusion criteria, which requires the examination of the whole nodule and its capsule. Spindle cell proliferations, especially of follicular cell origin, arising within thyroid follicular neoplasms are very rare and may cause diagnostic difficulties. Few reports described spindle cell proliferations arising in follicular thyroid adenoma and papillary thyroid carcinoma. To the best of our knowledge, only one case has been reported in NIFTP so far. In this article, we report a unique case of NIFTP associated with a spindle cell proliferation that was characterized immunohistochemically. Specific issues related to this case are discussed.

Risk prediction in children and adults less than 45 years old with papillary thyroid cancer

The incidence of papillary thyroid cancer is increasing faster than any other cancer in young patients. The purpose of this review is to discuss the most recent determinants of risk of recurrence and compromised outcomes in this population. Areas covered: This review discusses the most updated data on patient age, including children and young adults, extent of disease and subsequent dynamic staging over time, molecular markers for disease aggressiveness, adequacy of surgical resection and surgeon volume, and novel therapies for advanced non-resectable disease as predictors of patient outcomes. Expert commentary: Young patients enjoy excellent outcomes, with long-term survivorship, but face higher risks of short-term complications and disease recurrence. Thoughtful evaluation of the extent of disease, tumor features associated with more aggressive behavior, the presence of locoregional or distant metastases, and an understanding of molecular changes in their tumors are important areas of consideration. High-volume surgeons should work collaboratively with endocrinologists, radiologists, and pathologists specializing in thyroid cancer to help patients achieve excellent outcomes. Emerging data challenging the status quo regarding the relative importance of patient age, tumor features, and dynamic risk-adjustment for overall prognosis of these patients will likely impact future care and staging systems.

Defining Papillary Carcinoma of the Thyroid: A Short Review and Analysis

OBJECTIVES

To review how changes in the pathologic definitions for papillary tumors of the thyroid during recent decades have affected outcomes for patients with these tumors.

METHODS

Forty-nine previous reports or studies involving collectively 53,606 patients were reviewed, and new analyses were performed on the data to include analyses of agreement, incidence, survival, and diagnostic categories.

RESULTS

The past emphasis on cytologic features to define papillary tumors has not resulted in ideal pairwise agreement between pathologists and has produced incidence and survival data suggesting overdetection and overdiagnosis. Most recently, tissue patterns have been reemphasized.

CONCLUSIONS

With the recent reemphasis on diagnostic tissue patterns (over cytologic criteria), agreements between pathologists for the diagnosis of papillary tumors should improve, and the incidence of papillary carcinoma should decline. Nevertheless, updated survival analyses demonstrate excellent long-term survival for most of those diagnosed with papillary carcinomas.

Update on the cytologic features of papillary thyroid carcinoma variants

Papillary thyroid cancer (PTC), which accounts for 85-90% of all thyroid cancers, is generally an indolent tumor with long term survival rates >95%. A reliable definitive diagnosis of PTC is usually straightforward in fine needle aspirates of conventional PTC whenever the characteristic papillary and/or flat honeycomb sheet-like architecture and the typical nuclear features of chromatin pallor, nuclear enlargement, crowding, grooves and pseudoinclusions are encountered. Conventional PTC, however, has diminished in relative frequency as compared to PTC variants, especially the noninvasive follicular variant of PTC, an indolent tumor which has recently been reclassified as "noninvasive follicular thyroid neoplasm with papillary-like nuclear features" (NIFTP). These PTC variants are characterized by various architecture, cell type and shape, and stromal features, some of which can be recognized cytologically. Awareness of the cytomorphological spectrum and of the characteristic cytological features of these PTC variants is important to avoid diagnostic pitfalls. In this article, we review the different variants of PTC, including their cytomorphologic features, differential diagnosis, and salient molecular features. Diagn. Cytopathol. 2017;45:714-730. © 2017 Wiley Periodicals, Inc.

Prognostic indicators for papillary thyroid carcinoma

Differentiated thyroid cancer (DTC) includes more than 90% of all thyroid carcinoma and its incidence is growing, mainly due to an increase in the incidence of papillary thyroid cancer (PTC) for the widespread use of neck ultrasonography. Areas covered: Several prognostic factors should be considered during the management of PTC in order to provide the most effective treatment. The most important prognostic factors in PTC include personal and pathological features such as patient's age, gender, hystotype, tumor size, extrathyroidal extension, lymph node involvement, presence of local or distant metastases and molecular analyses. We performed a search in the PubMed database for studies published in English since 1960 using the terms: 'thyroid cancer', 'prognostic factors', 'age', 'gender', 'hystotype', 'tumor size', 'extrathyroidal extension', 'lymph node', 'metastases' and 'molecular analyses'. Expert commentary: Prognostic factors can guide clinicians during the treatment and follow-up of DTC patients, but it is now evident that the risk of recurrence or death must be evaluated periodically, on the basis of individual risk, according to the response to initial therapy or the subsequent therapy required during follow-up.

Current Guidelines for Postoperative Treatment and Follow-Up of Well-Differentiated Thyroid Cancer

Well-differentiated thyroid cancer is increasing in incidence but the disease-specific mortality remains very low. The only effective adjuvant treatment is radioactive iodine ablation. Guidelines regarding the use and dosage of radioactive iodine depend on pathologic features of the primary and metastatic tumor that define risk. Long-term treatment includes thyroid-stimulating hormone suppression and surveillance with serum thyroglobulin and radiologic assessment for nodal recurrence.

Sonographic and cytopathologic correlation of papillary thyroid carcinoma variants

Papillary thyroid carcinoma (PTC) is the most common thyroid cancer and constitutes more than 70% of thyroid malignancies. Although TNM staging is the most widely used parameter for determination of therapeutic plans, recent studies have suggested that different histopathologic variants of PTC can also have different clinical courses and patient prognoses. Sonographic criteria for PTC are well established and include a taller-than-wide shape, an irregular margin, microcalcifications, and marked hypoechogenicity. The role of sonography has expanded to enable the characterization of PTC variants based on their sonographic features. Tall cell and diffuse sclerosing variants appear to have more aggressive clinical courses with unfavorable prognoses, whereas the more recently described cribriform-morular and Warthin-like variants have relatively indolent clinical courses. The prognoses of patients with follicular, solid, columnar cell, and oncocytic variants are still controversial and may be similar to the prognosis of conventional PTC. Understanding the sonographic characteristics of PTC variants with clinicopathologic correlation may be helpful for suggesting an appropriate treatment plan.

Cytomorphology of columnar cell variant of papillary carcinoma thyroid: A case report and review of the literature

A 58 years old lady reported with history of progressively increasing lump in the neck. Patient had earlier undergone sub-total thyroidectomy (details not available) in a private institute one year back. Fine needle aspiration cytology (FNAC) of the present lump revealed features of papillary carcinoma thyroid. Patient subsequently underwent total thyroidectomy along with excision of a tumor nodule in the larynx. Gross examination of the specimen revealed a tumor nodule in the right lobe of the thyroid. Microscopic examination of the tumor nodule in the thyroid and larynx revealed a columnar cell variant of papillary carcinoma thyroid. Very few reports describing the cytomorphologic features of this variant of papillary carcinoma are available in the published literature. These reports highlight the absence or paucity of nuclear grooves and intranuclear inclusions in this variant. We describe a case of columnar cell variant of papillary carcinoma where nuclear grooves were prominently seen. In addition, we report the occurrence of rosette-like structures which were brought out better on FNA smears. These rosette-like structures have not been emphasized earlier in the published literature. The cytomorphologic features of this rare variant are also reviewed in this report.

Aggressive variants of follicular cell-derived thyroid carcinomas: a cytopathologist's perspective

Follicular cell-derived carcinomas of the thyroid gland comprise a heterogeneous group of malignant neoplasms of the thyroid gland with varied histologic appearance and molecular profiles. In most patients, these tumors represent relatively indolent neoplasms; however, certain subtypes/variants behave in an aggressive manner, and the recognition of this subset of tumors is essential because of their variable response to therapy and significant morbidity and mortality. Fine-needle aspiration is considered an essential tool for the diagnosis of suspicious thyroid nodules. In this review, the authors discuss the clinical, histologic, and molecular findings and the prognostic implications of aggressive thyroid neoplasms with emphasis on the characteristic cytomorphologic features on fine-needle aspiration smears.

Aggressive variants of follicular cell derived thyroid carcinoma; the so called 'real thyroid carcinomas'

The pathological diagnoses and classification schemes for thyroid carcinoma have changed over the past 20 years and continue to do so. New entities have been described and molecular analyses have suggested better characterisation and grouping of certain tumours. Because some of the lesions have been named differently by different authors, clinicians and patients may be confused as to what a specific patient's lesion represents. In this review, we discuss the thyroid tumours of follicular origin which are clinically unusual but important to recognise as their behaviour may be aggressive, they may not respond to radioiodine treatment and they may cause significant mortality. This paper describes these important but rare lesions, their pathological features, important clinicopathological correlations, molecular correlates and prognostic implications.

Clinicopathological and molecular characterization of nine cases of columnar cell variant of papillary thyroid carcinoma

The majority of papillary thyroid carcinoma is indolent and associated with long-term survival. The columnar cell variant, however, is a rare subtype that is variable in biological behavior; some are clinically aggressive, whereas others are more clinically indolent. Tumor size, tumor circumscription, and encapsulation may influence the behavior of columnar cell carcinomas. Other variables including genetic changes and putative biomarkers associated with malignant growth have not been thoroughly examined in these neoplasms. In this study, nine cases of columnar cell variant of papillary thyroid carcinoma from three institutions were classified as clinically indolent or aggressive based on pathological features, clinical history, and outcome. Indolent tumors were typically small, circumscribed or encapsulated, and from younger female patients, whereas aggressive tumors were large, locally aggressive, associated with regional and distant metastasis, and from older male patients. The missense mutation, V600E in the BRAF oncogene (BRAF(V600E)), was detected in three of nine of cases, of which two were clinically aggressive. Immunohistochemical evaluation of neoplasia-associated markers showed increased nuclear cyclin D1 expression, elevated Ki-67 proliferation indices, and predominantly weak nuclear p53 staining in both indolent and aggressive tumors. Expression of β-catenin was largely restricted to a membranous pattern in both tumor types. Cytoplasmic expression of bcl-2 was overall mildly reduced in indolent neoplasms. Nuclear expression of estrogen and progesterone receptors was increased in both indolent and aggressive neoplasms, but was without sex- or age-related differences; however, whereas progesterone receptor expression was diffuse and strong in clinically indolent carcinomas, its expression was diminished in aggressive neoplasms. Recognition of the clinicopathological characteristics and the molecular and immunophenotypic features of the columnar cell variant of papillary thyroid carcinoma may aid in characterizing neoplasms that behave indolently or aggressively.

Tumor margin histology predicts tumor aggressiveness in papillary thyroid carcinoma: a study of 514 consecutive patients

Histologic patterns at tumor margins may be related to prognosis in several malignancies. We investigated tumor aggressiveness with respect to tumor margin histology in patients with papillary thyroid carcinoma (PTC). Five hundred fourteen consecutive patients who underwent surgery for primary PTC between January and July 2009 were assigned to two groups, one with an infiltrative pattern (I-type, n = 347) at tumor margins and one with an expanding pattern (E-type, n = 167). Tumor aggressiveness was assessed by analyzing relationships between these patterns and known prognostic factors. The analysis showed that unfavorable prognostic factors such as tumor multiplicity (P = 0.002), extrathyroidal extension (P < 0.001), lateral neck lymph node metastasis (P < 0.001) and advanced TNM stage (P = 0.001) were significantly more prevalent in patients with I-type PTC than in those with the E-type. Central neck node metastases were more prevalent without statistical significance in the I-type patients (P = 0.376). Tumor margin histology was not related to gender or tumor size. These results suggest that histologic patterns at tumor margins predict aggressiveness in PTC.

Aggressive variants of papillary thyroid carcinoma

A number of histologic variants of well-differentiated papillary carcinoma have been found to be associated with more aggressive tumor behavior. Tall cell, columnar cell, diffuse sclerosing, solid/trabecular, and insular variants of well-differentiated papillary thyroid cancer are all potentially more aggressive than conventional papillary thyroid cancer. When subjected to multivariate analysis, however, evidence that the histologic subtype of tumor is an independent predictor of outcome is weak. Rather, the aggressive variants tend to present with features recognized by other staging systems as associated with a worse prognosis, including higher histologic grade, extracapsular spread, large tumor size, and the presence of distant metastases. Prognosis is directly related to the presence of these features. The state of our knowledge is limited by the relatively small number of cases that have been studied. The presence of an aggressive variant of papillary carcinoma should alert the surgeon that he is dealing with a potentially aggressive tumor. Clinical treatment decisions should be based on the stage of the disease, influenced by the knowledge that the aggressive variants tend to be associated with higher risk factors. The surgeon must be prepared to perform at the first, or second stage, a total thyroidectomy, central compartment neck dissection, additional lymphadenectomy, and/or resection of invaded surrounding structures, and search for distant metastasis. Postoperative radioactive iodine should generally be administered for these variants as they will generally be intermediate to advanced tumors. The tall cell variant is often refractory to such treatment but may be susceptible to treatment targeted against BRAF mutation. External beam irradiation may be used in cases of incomplete resection.