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

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.

Prediction of classical versus non classical papillary thyroid carcinoma subtypes from cytology of nodules classified according to TIRADS

PURPOSE

Our purposes were: 1) to estimate the prediction performance (PP) of cytology in identifying papillary thyroid carcinoma (PTC) subtypes; 2) to explore how the PTC subtypes distribute among the American College of Radiology (ACR) Thyroid Imaging Reporting and Data System (TI-RADS) categories.

METHODS

Nodules were included if both the histology with the PTC subtype report and the cytology report with the possible PTC subtype were available. The PP was calculated by making the proportion of True positives/False positives+false negatives.

RESULTS

309 cytologically "suspicious for malignancy" and "malignant" thyroid nodules with PTC histology were evaluated. ACR TI-RADS categorization for classical PTC was significantly different from non-classical PTC (p-value 0.02). For the whole cohort the PP of cytologically classical cases was 0.74, while that of cytologically non classical cases was 0.41. ACR TI-RADS categorization was not significantly different for aggressive vs non-aggressive PTC subtypes (p-value 0.1). When considering only aggressive or non-aggressive PTC subtypes, the PP of cytologically classical cases was respectively 0.86 and 0.87, while that of cytologically non classical cases was respectively 0.27 and 0.22. The PP of cytologically classical cases was 0.73 and 0.79, respectively for macroPTCs and microPTCs, while that of cytologically non classical cases was 0.55 and 0.33, respectively for macroPTCs and microPTCs.

CONCLUSION

Cytology examination reliably performed in predicting classical PTC versus non classical PTC subtypes. ACR TI-RADS categorization was significantly different among classical PTC versus non classical PTC subtypes.

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.

FNA cytology of columnar cell variant of papillary thyroid carcinoma: A case report with review of literature

Cytological features such as papillary configuration, pseudostratification, and large rosette‐like clusters without any nuclear features of PTC hint at the CCVPTC diagnosis.

The presence of papillary configuration, pseudostratification, and large rosette‐like clusters without any nuclear features of PTC hint at CCVPTC.

Rare Columnar Cell Variant Papillary Thyroid Carcinoma with Metastasis to Pancreas and Lungs at Initial Presentation: A Case Report and Review of Literature

Papillary thyroid cancer (PTC) is the most common endocrine malignancy, accounting for 85% of differentiated thyroid cancers. A small percentage of PTC variants are considered more aggressive, such as the tall cell variant associated with the V600E mutation in the BRAF gene and the rarer columnar variant, which is described in only 0.2% of cases and has a poor prognosis. Although locoregional metastases to neck lymph nodes are common, distant metastases of PTC are rare at presentation with only 5 to 7% reported in the literature. We present a very rare case of columnar cell variant PTC with synchronous metastasis to the lungs and indolent focus in the pancreas at initial diagnosis, which has never been reported in the literature. Our patient presented with non-radioactive iodine (RAI) responsive PTC with diffuse metastases to the lungs and one synchronous focal metastatic lesion in the pancreas. After multidisciplinary discussions, pancreatectomy/metastasectomy was deferred due to the disseminated PTC with multiple metastases to the lungs, lack of pancreas-related symptoms in the patient, and inherent complication risks. The patient was treated with systemic therapy using a tyrosine kinase inhibitor (lenvatinib), which is the standard of care for non-RAI responsive PTC and showed a complete radiologic resolution of the pancreatic lesion, however, with partial yet nonprogressive metastatic disease in the lungs.

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.

Update from the 2022 World Health Organization Classification of Thyroid Tumors: A Standardized Diagnostic Approach

The fifth edition of the World Health Organization (WHO) histologic classification of thyroid neoplasms released in 2022 includes newly recognized tumor types, subtypes, and a grading system. Follicular cell-derived neoplasms are categorized into three families (classes): benign tumors, low-risk neoplasms, and malignant neoplasms. The terms "follicular nodular disease" and "differentiated high-grade thyroid carcinoma" are introduced to account for multifocal hyperplastic/neoplastic lesions and differentiated thyroid carcinomas with high-grade features, respectively. The term "Hürthle cells" is replaced with "oncocytic cells." Invasive encapsulated follicular and cribriform morular variants of papillary thyroid carcinoma (PTC) are now redefined as distinct tumor types, given their different genetic alterations and clinicopathologic characteristics from other PTC subtypes. The term "variant" to describe a subclass of tumor has been replaced with the term "subtype." Instead, the term "variant" is reserved to describe genetic alterations. A histologic grading system based on the mitotic count, necrosis, and/or the Ki67 index is used to identify high-grade follicular-cell derived carcinomas and medullary thyroid carcinomas. The 2022 WHO classification introduces the following new categories: "salivary gland-type carcinomas of the thyroid" and "thyroid tumors of uncertain histogenesis." This review summarizes the major changes in the 2022 WHO classification and their clinical relevance.

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.

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.

The Extent of Therapeutic Central Compartment Neck Dissection in Unilateral cT1N1a or cT2N1a Papillary Thyroid Carcinoma

Purpose

Papillary thyroid carcinomas (PTCs) frequently metastasize to the central neck compartment. Therapeutic central compartment neck dissection (CCND) is a well-established treatment for PTC nodal metastases; however, the extent to which therapeutic CCND should be performed remains controversial. In this study, we investigated the predictive risk factors for contralateral paratracheal lymph node metastasis (LNM) in unilateral cT1N1a or cT2N1a PTC.

Patients and Methods

In this case–control study, which was conducted at a single center, demographic and pathological data from unilateral cT1N1a or cT2N1a PTC patients were collected from January 2017 to March 2019. All patients were treated with total thyroidectomy and bilateral CCND.

Results

Two hundred thirty-seven patients met the inclusion criteria. Forty-nine patients (20.7%) were diagnosed with positive lymph nodes in the contralateral paratracheal region. Male sex (p=0.003), T2 disease (21–40 mm) (p<0.001), inferior pole tumor (p=0.011), near isthmus tumor (p<0.001), aggressive pathology (p<0.001), intraglandular dissemination (p=0.009), pretracheal LNM (p<0.001), >5 metastatic lymph nodes (p<0.001) and extranodal invasion (p=0.003) were significantly associated with contralateral paratracheal LNM in univariate analysis. Multivariate analysis showed that male sex (p=0.005, OR=17.545), T2 disease (p=0.003, OR=34.317), inferior pole tumor (p=0.022, OR=8.289), near isthmus tumor (p=0.001, OR=40.229), aggressive pathology (p=0.027, OR=48.063), pretracheal LNM (p=0.002, OR=14.235) and >5 metastatic lymph nodes (p=0.025, OR=23.426) were independent risk factors for contralateral paratracheal LNM.

Conclusion

Male sex, T2 disease, a tumor located near the isthmus or inferior pole, aggressive pathology, pretracheal LNM and >5 metastatic lymph nodes were predictive factors for contralateral paratracheal LNM in unilateral cT1N1a or cT2N1a PTC. These data may be useful to identify targets for surveillance or develop therapeutic interventions for patients with CCND.

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.