Cribriform-Morular Thyroid Carcinoma Is a Distinct Thyroid Malignancy of Uncertain Cytogenesis

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.

A Case of Cribriform-Morular Thyroid Carcinoma Presenting Without Thyroid Nodule

Cribriform-morular thyroid carcinoma is a rare type of thyroid cancer. It has a strong association with familial adenomatous polyposis (FAP), a hereditary genetic disorder that predisposes individuals to the development of numerous polyps in the colon and rectum. We describe the case of a young female patient who presented with an enlarging goiter, notably without detectable thyroid nodules or masses on ultrasound, who after total thyroidectomy was found to have cribriform-morular thyroid carcinoma. This diagnosis led to genetic testing and diagnosis of FAP syndrome. We demonstrate that this rare thyroid carcinoma may present with nonsuspicious findings on sonographic evaluation while being a valuable harbinger in the diagnosis of FAP syndrome.

Cribriform Morular Thyroid Carcinoma: A Rare Case and Associated Uncommon Features

Cribriform morular thyroid carcinoma has been added under tumors of uncertain histogenesis. Its peculiar clinical, histomorphological pattern, and immunohistochemical profile have been proved different from papillary thyroid carcinoma. A 59-year-old female patient had a lesion in the left lobe of the thyroid. Fine needle aspiration cytology was reported as medullary thyroid carcinoma. The total thyroidectomy specimen showed a predominantly solid tumor of size 9.5 cm in the left lobe. Microscopy showed a mixed growth pattern with the dominant cribriform and solid morular area. Nuclear features of papillary carcinoma were not seen. Squamoid morules had nuclear clearing. Marked stromal hyalinization and calcification were noted. Extrathyroidal extension, lymphovascular invasion, and lymph node metastasis were not identified. Immunohistochemically the tumor cells were diffuse and strong nuclear positive for β-catenin, TTF1, PAX8, estrogen receptor, focal, and weak positivity for CD5. Synaptophysin, calcitonin, thyroglobulin, and CDX2 were negative. We report this rare cribriform morular thyroid carcinoma case with its associated uncommon histological and immunohistochemical features.

Cribriform Morular Thyroid Carcinoma - Ultimobranchial Pouch-Related? Deep Molecular Insights of a Unique Case

A 44-year-old female patient with a familial adenomatous polyposis (FAP) was diagnosed with a cribriform morular thyroid carcinoma (CMTC). We observed within the very necrotic tumor a small but distinct poorly differentiated carcinomatous component. As expected, next generation sequencing of both components revealed a homozygous APC mutation and in addition, a TERT promoter mutation. A TP53 mutation was found exclusively in the CMTC part, while the poorly differentiated component showed a clonal evolution, harboring an activating PIK3CA mutation and copy number gains of BRCA2, FGF23, FGFR1, and PIK3CB-alterations which are typically seen in squamous cell carcinoma. The mutational burden in both components was low, and there was no evidence for microsatellite instability. No mutations involving the mitogen-activated protein kinase (MAPK) pathway, typically seen in papillary thyroid carcinomas, were detected. Immunohistochemically, all tumor parts were negative for thyroglobulin, providing further evidence that this entity does not belong to the follicular epithelial cell-derived thyroid carcinoma group. CD5 was negative in the poorly differentiated component, making a relation to intrathyroidal thymic carcinoma rather unlikely. However, since this marker was seen in the morules, a loss in the poorly differentiated component and a relation to the ultimobranchial body cannot be excluded either. After total thyroidectomy and radioiodine ablation, the patient was disease-free with no residual tumor burden on 2-year follow-up.

The First Case of Cribriform-Morular Thyroid Carcinoma and FAP with APC Gene Mutation in China: A Case Report and Brief Review

The cribriform-morular variant of papillary thyroid carcinoma (CMV-PTC) is now designated as morular cribriform thyroid carcinoma (CMTC) according to the 5^th edition of the World Health Organization (WHO) Classification of Thyroid Tumors. CMTC can appear within a familial adenomatous polyposis (FAP) or be sporadic. We report the first case of a young female patient in China who was diagnosed with FAP and CMTC with a mutation in exon 16 of the APC gene underlying the disease. The main purpose of this case report is to provide a special pathological type of thyroid tumors, which is expected to be helpful for clinical work in the future.

Cribriform morular thyroid carcinoma: a case report with pathological, immunohistochemical, and molecular findings suggesting an origin from follicular cells (or their endodermal precursors)

Cribriform morular thyroid carcinoma (CMTC) is a rare malignant thyroid tumor with a peculiar growth pattern secondary to permanent activation of the WNT/β-catenin pathway. CMTC may be associated with familial adenomatous polyposis or sporadic; it shares morphological features with papillary thyroid carcinoma (PTC) and was considered a variant of PTC in the 2017 WHO classification of tumors of endocrine organs. The new 5th edition of the WHO classification of endocrine and neuroendocrine tumors considered CMTC an independent thyroid neoplasm of uncertain histogenesis. A thymic/ultimobranchial pouch-related differentiation in CMTC has been recently postulated. We, however, have used the pathological and immunohistochemical features of this case of CMTC with 2 novel oncogenic somatic variants (c.3428_3429insA, p.(Tyr1143Ter) and c.3565del, p. (Ser1189Hisfs*76) of the APC gene to propose an origin from follicular cells (or their endodermal precursors). As usual in CMTC, the morular component of this tumor was positive for CDX2. Given the fact that WNT/β-catenin signaling, through CDX2, activates large intestine and small intestine gene expression, we postulate that in CMTC, the tumor cells have their terminal differentiation blocked, thus showing a peculiar primitive endodermal (intestinal-like) phenotype negative for sodium-iodide symporter, thyroperoxidase, and thyroglobulin. Establishing the histogenesis of CMTC is very relevant for the development of appropriate therapies of redifferentiation, particularly in patients where the tumor cannot be controlled by surgery.

The 2022 WHO classification of thyroid tumors: novel concepts in nomenclature and grading

The fifth edition of the Classification of Endocrine and Neuroendocrine Tumors has been released by the World Health Organization. This timely publication integrates several changes to the nomenclature of non-neoplastic and neoplastic thyroid diseases, as well as novel concepts that are essential for patient management. The heterogeneous group of non-neoplastic and benign neoplastic lesions are now collectively termed as 'thyroid follicular nodular disease' to better reflect the clonal and non-clonal proliferations that clinically present as multinodular goiter. Thyroid neoplasms originating from follicular cells are distinctly divided into benign, low-risk and malignant neoplasms. The new classification scheme stresses that papillary thyroid carcinoma (PTC) should be subtyped based on histomorphologic features irrespective of tumor size to avoid treating all sub-centimeter/small lesions as low-risk disease. Formerly known as the cribriform-morular variant of PTC is redefined as cribriform-morular thyroid carcinoma since this tumor is now considered a distinct malignant thyroid neoplasm of uncertain histogenesis. The 'differentiated high-grade thyroid carcinoma' is a new diagnostic category including PTCs, follicular thyroid carcinomas and oncocytic carcinomas with high-grade features associated with poorer prognosis similar to the traditionally defined poorly differentiated thyroid carcinoma as per Turin criteria. In addition, squamous cell carcinoma of the thyroid is now considered a morphologic pattern/subtype of anaplastic thyroid carcinoma. In this review, we will highlight the key changes in the newly devised fifth edition of the WHO classification scheme of thyroid tumors with reflections on its applicability in patient management and future directions in this field.

Cribriform-morular thyroid carcinoma: A case report with review of the literature

Cribriform-morular thyroid carcinoma (CM-TC) is a rare entity that usually occurs in association with familial adenomatous polyposis (FAP) but may be sporadic. Herein, we present a new case of cribriform-morular thyroid carcinoma occurring in a 28-year-old woman with no history of FAP.

The Classic, the Trendy, and the Refashioned: A Primer for Pathologists on What Is New in Familial Endocrine Tumor Syndromes

Familial endocrine tumor syndromes are continuously expanding owing to the growing role of genetic testing in routine clinical practice. Pathologists are usually the first on the clinical team to encounter these syndromes at their initial presentation; thus, recognizing them is becoming more pivotal in routine pathology practice to help in properly planning management and further family testing. Our increasing knowledge about them is reflected in the newer syndromes included in the new World Health Organization classification and in the evolving discovery of new endocrine tumors and new familial associations. In many of these syndromes, the clinical features and co-occurrence of multiple neoplasia are the only clues (multiple endocrine neoplasia syndromes). In other syndromes, specific morphologic findings (pituitary blastoma and DICER1 syndrome, cribriform morular thyroid carcinoma, and AFP syndrome) and available ancillary studies (SDHB in SDH-deficient tumor syndromes) can aid pathologists. The aim of this review is to provide a primer on recent updates on familial endocrine tumor syndromes and related tumors, focusing on recent classification changes or tumor syndromes where a clearer role for pathologists is at play.

Post-radiotherapy cribriform-morular thyroid carcinoma

BACKGROUND

According to the new 2022 World Health Organization classification of endocrine tumors, thyroid malignancy, formerly known as the cribriform-morular variant of papillary thyroid carcinoma, is now categorized as differentiated thyroid malignancy; it is, at present, called cribriform-morular thyroid carcinoma and classified as a tumor of unknown histogenesis.

CASE REPORT

In this case report, we report on a 15-year-old patient who underwent external radiotherapy to the neck for Hodgkin's disease and developed cribriform-morular thyroid carcinoma 5 years after radiotherapy.

CONCLUSIONS

We believe that cribriform-morular thyroid carcinoma with diffuse nuclear beta-catenin expression has exciting and unresolved uncertainties that may affect disease prognosis and follow-up for cytopathologists and endocrinologists.

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.

Management of thyroid nodules

In the past 30 years, there has been a substantial rise in the detection of thyroid nodules. Largely asymptomatic, thyroid nodules are most often incidental findings that typically pose minimal risk. Data supporting these findings show a rapid rise in the incidental detection of thyroid nodules and cancer, but minimal effect on mortality rates, despite treatment. These data imply that historical approaches to thyroid nodule and cancer care might at times include unnecessary or excessive care. To address this issue, the past decade has witnessed an increasingly conservative approach to nodule management, seeking to individualise care and provide the most focused intervention that leads to favourable outcomes. Benign nodules can be safely monitored with minimal, or long-interval follow-up imaging. Molecular testing should be considered for cytologically indeterminate nodules because of its ability to improve preoperative cancer risk determination and reduce unnecessary surgery. The treatment of biopsy-proven malignant nodules has become increasingly nuanced, since recommendations for near-total thyroidectomy are no longer routine. Hemithyroidectomy is now commonly considered when operative intervention is favoured. Some patients with small volume, isolated cancerous nodules are safely managed non-operatively with active monitoring. In summary, modern management strategies for thyroid nodular disease seek to incorporate the growing amount of available diagnostic and prognostic data, inclusive of demographic, radiological, pathological and molecular findings. Once obtained, an individualised management plan can be effectively formulated.

Overview of the 2022 WHO Classification of Thyroid Neoplasms

This review summarizes the changes in the 5th edition of the WHO Classification of Endocrine and Neuroendocrine Tumors that relate to the thyroid gland. The new classification has divided thyroid tumors into several new categories that allow for a clearer understanding of the cell of origin, pathologic features (cytopathology and histopathology), molecular classification, and biological behavior. Follicular cell-derived tumors constitute the majority of thyroid neoplasms. In this new classification, they are divided into benign, low-risk, and malignant neoplasms. Benign tumors include not only follicular adenoma but also variants of adenoma that are of diagnostic and clinical significance, including the ones with papillary architecture, which are often hyperfunctional and oncocytic adenomas. For the first time, there is a detailed account of the multifocal hyperplastic/neoplastic lesions that commonly occur in the clinical setting of multinodular goiter; the term thyroid follicular nodular disease (FND) achieved consensus as the best to describe this enigmatic entity. Low-risk follicular cell-derived neoplasms include non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP), thyroid tumors of uncertain malignant potential, and hyalinizing trabecular tumor. Malignant follicular cell-derived neoplasms are stratified based on molecular profiles and aggressiveness. Papillary thyroid carcinomas (PTCs), with many morphological subtypes, represent the BRAF-like malignancies, whereas invasive encapsulated follicular variant PTC and follicular thyroid carcinoma represent the RAS-like malignancies. This new classification requires detailed subtyping of papillary microcarcinomas similar to their counterparts that exceed 1.0 cm and recommends not designating them as a subtype of PTC. The criteria of the tall cell subtype of PTC have been revisited. Cribriform-morular thyroid carcinoma is no longer classified as a subtype of PTC. The term "Hürthle cell" is discouraged, since it is a misnomer. Oncocytic carcinoma is discussed as a distinct entity with the clear recognition that it refers to oncocytic follicular cell-derived neoplasms (composed of > 75% oncocytic cells) that lack characteristic nuclear features of PTC (those would be oncocytic PTCs) and high-grade features (necrosis and ≥ 5 mitoses per 2 mm²). High-grade follicular cell-derived malignancies now include both the traditional poorly differentiated carcinoma as well as high-grade differentiated thyroid carcinomas, since both are characterized by increased mitotic activity and tumor necrosis without anaplastic histology and clinically behave in a similar manner. Anaplastic thyroid carcinoma remains the most undifferentiated form; squamous cell carcinoma of the thyroid is now considered as a subtype of anaplastic carcinoma. Medullary thyroid carcinomas derived from thyroid C cells retain their distinct section, and there is a separate section for mixed tumors composed of both C cells and any follicular cell-derived malignancy. A grading system for medullary thyroid carcinomas is also introduced based on mitotic count, tumor necrosis, and Ki67 labeling index. A number of unusual neoplasms that occur in the thyroid have been placed into new sections based on their cytogenesis. Mucoepidermoid carcinoma and secretory carcinoma of the salivary gland type are now included in one section classified as "salivary gland-type carcinomas of the thyroid." Thymomas, thymic carcinomas and spindle epithelial tumor with thymus-like elements are classified as "thymic tumors within the thyroid." There remain several tumors whose cell lineage is unclear, and they are listed as such; these include sclerosing mucoepidermoid carcinoma with eosinophilia and cribriform-morular thyroid carcinoma. Another important addition is thyroblastoma, an unusual embryonal tumor associated with DICER1 mutations. As in all the WHO books in the 5th edition, mesenchymal and stromal tumors, hematolymphoid neoplasms, germ cell tumors, and metastatic malignancies are discussed separately. The current classification also emphasizes the value of biomarkers that may aid diagnosis and provide prognostic information.

Update from the 5th Edition of the World Health Organization Classification of Head and Neck Tumors: Familial Tumor Syndromes

The initiative of the 5th edition of the WHO classification of the Head and Neck Tumours establishing a new section dedicated to familial/heritable tumor syndromes with tumors and lesions in the head and neck region was much needed to better understand the tumours, diseases, and associated syndromes, as well as establish recommendations for monitoring and treating these patients. (WHO Classification of Tumours Editorial Board. Head and Neck tumours. Lyon (France): International Agency for Research on Cancer; 2022. https://publications.iarc.fr/ ). Within the newly established chapter on genetic tumor syndromes, we have described the main manifestations on the head and neck region in 15 syndromes. This review highlights the important findings within these syndromes, especially on the update on syndromes with tumors involving the head and neck region, as Gorlin syndrome/nevoid basal cell carcinoma syndrome associated with odontogenic keratocysts; Brooke-Spiegler syndrome/familial cylindromatosis and the associated membranous-type salivary gland basal cell adenoma, PTEN hamartoma tumor syndrome/Cowden syndrome with associated facial skin and mucosal lesions and characteristic multinodular thyroid lesions, Von Hippel Lindau syndrome and the associated middle ear endolymphatic sac tumor, as well as the fascinating genetic aspects of the diverse Head and Neck Paragangliomas. We will also discuss hyperparathyroidism-jaw tumor syndrome is characterized by parathyroid tumors in association with fibro-osseous jaw tumors, as well as head and neck desmoid tumors associated with familial adenomatous polyposis with Gardner syndrome variant familial, multicentric head and neck squamous cell carcinoma, tuberous sclerosis and neurofibromatosis type 1-associated head and neck lesions.

Overview of the 2022 WHO Classification of Familial Endocrine Tumor Syndromes

This review of the familial tumor syndromes involving the endocrine organs is focused on discussing the main updates on the upcoming fifth edition of the WHO Classification of Endocrine and Neuroendocrine Tumors. This review emphasizes updates on histopathological and molecular genetics aspects of the most important syndromes involving the endocrine organs. We describe the newly defined Familial Cancer Syndromes as MAFA-related, MEN4, and MEN5 as well as the newly reported pathological findings in DICER1 syndrome. We also describe the updates done at the new WHO on the syndromic and non-syndromic familial thyroid diseases. We emphasize the problem of diagnostic criteria, mention the new genes that are possibly involved in this group, and at the same time, touching upon the role of some immunohistochemical studies that could support the diagnosis of some of these conditions. As pathologists play an important role in identifying tumors within a familial cancer syndrome, we highlight the most important clues for raising the suspicious of a syndrome. Finally, we highlight the challenges in defining these entities as well as determining their clinical outcome in comparison with sporadic tumors. Instead of the usual subject review, we present the highlights of the updates on familial cancer syndromes by answering select questions relevant to practicing pathologists.

Cribriform-morular variant of papillary thyroid carcinoma with poorly differentiated features: report of a case and review of the literature

Introduction

Cribrifrom-morular variant of papillary thyroid carcinoma (CMVPTC) is an uncommon thyroid neoplasm that occurs predominantly in women and is sometime associated with familial adenomatous polyposis (FAP). Some of these tumors may undergo dedifferentiation to poorly differentiated thyroid carcinoma (PDTC). We describe a rare case of this carcinoma in a women without a history of FAP.

Case presentation

A 49-year-old woman with a history of breast carcinoma presented with a thyroid mass. A CMVPTC was diagnosed after excision. There was no history of FAP. Histological examination showed classical features of CMVPTC in most areas, but about 20% of the carcinoma showed features of a poorly differentiated carcinoma with a solid pattern of growth, increase mitotic activity and a high Ki-67 proliferative index (25%). Immunohistochemical stains were positive for nuclear and cytoplasmic beta catenin staining. These special studies supported the diagnosis.

Conclusion

CMVPTC with dedifferentiation to PDTC is a rare carcinoma with only 4 previous documented cases in the literature. This aggressive variant of thyroid carcinoma is more common in females, as is CMVPTC, and is often associated with an aggressive biological course. The cases usually express nuclear beta catenin and estrogen, progesterone and androgen receptors have been reported in some cases. Some cases may have somatic alterations of the APC gene and TERT promoter mutations. These carcinomas may metastasize to lung, bones and lymph nodes. Because of its aggressive behavior, patient with this diagnosis should be treated aggressively to control disease spread and mortality from the carcinoma.

Squamous Differentiation in the Thyroid: Metaplasia, Neoplasia, or Bystander?

Background. Squamous differentiation within the thyroid is seen in a variety of settings. Squamous epithelium is non-native to the thyroid, and its debated origins span reactive metaplasia and developmental/embryologic remnants. Despite a lack of clarity as to its evolution, squamous epithelium may be associated with both neoplastic and non-neoplastic processes. Methods. Thyroid pathology reports spanning a 30-year period were reviewed for terms indicating squamous features. Associated diagnostic and clinical information was collated. Results. Four hundred and twenty seven of 17,452 (2.4%) thyroid surgical pathology cases during this period utilized terminology indicating squamous differentiation including 243 malignant (58%) and 178 benign (42%) diagnoses. There were 111 (26%) primary thyroid malignancies with squamous differentiation, 116 (28%) malignancies of non-thyroid origin including local extension from nearby cancers, and 16 (4%) malignancies of uncertain primary. Most benign lesions were non-neoplastic (84%). The minor subset representing benign neoplasia was interpreted as secondary reactive changes. Conclusion. While squamous differentiation is seen routinely in the thyroid, it is most commonly reported in malignancy. For primary thyroid malignancies reported to demonstrate a squamous component, biologically aggressive tumors were overrepresented. Available evidence suggests that multiple pathways may contribute to the presence of squamous epithelium in the thyroid including metaplasia of mature follicular cells, development from established embryonic remnants, or inception in putative, incompletely characterized stem-like cells. Our retrospective review presents an institutional landscape from which further investigation into the frequency and unique histologic and molecular context of intrathyroidal squamous differentiation as a driver or terminal event in thyroid pathophysiology.