An overview of the contemporary diagnosis and management approaches for anaplastic thyroid carcinoma.

Thyroid carcinoma is a complex disease with several types, the most common being well-differentiated and undifferentiated. The latter, "undifferentiated carcinoma", also known as anaplastic thyroid carcinoma (ATC), is a highly aggressive malignant tumor accounting for less than 0.2% of all thyroid carcinomas and carries a poor prognosis with a median survival of 5 months. BRAF gene mutations are the most common molecular factor associated with this type of thyroid carcinoma. Recent advances in targeted biological agents, immunotherapy, stem cell therapy, nanotechnology, the dabrafenib/trametinib combination therapy, immune checkpoint inhibitors (ICI) and artificial intelligence offer novel treatment options. The combination therapy of dabrafenib and trametinib is the current standard treatment for patients with BRAF-V600E gene mutations. Besides, the dabrafenib/trametinib combination therapy, ICI, used alone or in combination with targeted therapies have raised some hopes for improving the prognosis of this deadly disease. Younger age, earlier tumor stage and radiotherapy are all prognostic factors for improved outcomes. Ultimately, therapeutic regimens should be tailored to the individual patient based on surveillance and epidemiological data, and a multidisciplinary approach is essential.

Current status of anaplastic thyroid carcinoma.

In this editorial we comment on the article by Pavlidis et al, published in the recent issue of the World Journal of Oncology. We focus on the recent contributions in the management of anaplastic thyroid carcinoma, highlighting the importance of surgery and radiotherapy as first line therapies in its management and the introduction of new systemic therapies beyond chemotherapy, focused on molecular alterations, an essential step in the diagnosis and included in clinical guidelines for the selection of the ideal treatment. In contrast to other neoplasms, immunotherapy, is still beginning in studies of this pathology with encouraging results. Therefore, multimodal management of the pathology together with new drugs seems to be the logical step to increase the survival of this neoplasm.

Comprehensive genomic profiling from C-CAT database unveiled over 80% presence of oncogenic drivers in anaplastic thyroid carcinoma including BRAF, RAS family, NF1, and FGFR1.

OBJECTIVE: Anaplastic thyroid carcinoma (ATC) is considered a very aggressive carcinoma and has been difficult to treat with therapeutic strategies. This study examines the landscape of genomic alteration in ATC, including the BRAF V600E mutation, and its clinical implications. DESIGN, PATIENTS AND MESUREMENT: A retrospective observational study was conducted using collected at the Center for Cancer Genomics and Advanced Therapeutics (C-CAT) in Japan, utilizing comprehensive genomic profiling data from 102 ATC cases. Additionally, AACR-GENIE data from 267 cases were analysed for validation. Statistical methods, including the conditional Kendall tau statistic and χ2 tests, were employed for survival analysis and gene mutation comparisons. RESULTS: Among 102 ATCs, BRAF, RAS, and other driver mutations were found in 83 cases (81.2%). The prevalence of BRAF V600E mutations was as high as 60%. Co-mutation analysis identified different genomic profiles in the BRAF, RAS, and wild-type groups. Despite the diverse molecular backgrounds, no significant differences in clinical variables and overall survival were observed. The analysis considering left-side amputation suggested that RAS mutations had a poorer prognosis. In the BRAF/RAS wild-type group, FGFR1 and NF1 were identified as driver mutations, with an accumulation of copy number variations and less TERT promoter mutations. This molecular subgrouping was also supported by the AACR-GENIE data. CONCLUSIONS: Comprehensive genomic analysis of ATC in Japan revealed distinct molecular subgroups, highlighting the importance of BRAF V600E mutations, particularly V600E, as potential therapeutic targets and suggest the relevance of tailor-made therapeutic strategies based on genomic profiling.

Macrophage-Induced Carboxypeptidase A4 Promotes the Progression of Anaplastic Thyroid Cancer.

Background: The density of tumor-associated macrophages in the tumor microenvironment of anaplastic thyroid cancer (ATC) is associated with poor prognosis. However, the crosstalk between macrophages and ATC cells is poorly understood. This study aimed to examine the impact of macrophages on cancer cell phenotypes. We found a new mediator between M2 macrophages and ATC cells through proteomics analysis. Methods: The role of macrophages in proliferation, migration, and invasion of ATC cells was evaluated using coculture assay and conditioned medium (CM). Secretory factors in the CM from single or coculture were identified using liquid chromatography-tandem mass spectrometry proteomics analysis. We evaluated the role of the secretory factor in proliferation, migration, and invasion of cancer cells. In vivo xenograft model was used to evaluate the effect of the factor. Results: M2 macrophages significantly increased the proliferation, migration, and invasion of ATC cells, whereas M1 macrophages decreased the proliferation, migration, and invasion of ATC cells. Based on proteomic analysis of CM, we identify carboxypeptidase A4 (CPA4) as a mediator of the crosstalk between macrophages and ATC cells. CPA4 was only detected in the coculture media of M2 macrophage/8505C, and its expression in cancer cells increased by M2 macrophage. The expression of CPA4 protein was significantly higher in human thyroid cancers, particularly in ATCs, than normal and benign tissues. A bioinformatics analysis of public data revealed that CPA4 expression was associated with poor prognosis and dedifferentiation of thyroid cancer. Knockdown of CPA4 suppressed proliferation, colony formation, migration, and invasion of ATC cells, consistent with the decrease of STAT3, ERK, and AKT/mTOR phosphorylation and epithelial-mesenchymal transition (EMT) marker expression. In addition, the increased expression of CPA4 in cancer cells by M2 macrophage stimulation induced the polarization of macrophages to the M2 phenotype, which formed a positive feedback loop. Xenograft tumors did not develop after CPA4 knockdown. Conclusions: Our data suggest that CPA4 stimulates the progression of thyroid cancer by mediating between M2 macrophages and ATC cells. CPA4 can be a new therapeutic target for the treatment of patients with ATC.

Anaplastic Carcinoma Arising From a Mural Nodule in Benign Mucinous Cystadenoma.

Giant abdominopelvic tumors continue to present a diagnostic and therapeutic challenge for all surgeons despite all the advances in the world of imaging. Particularly, one of the most important challenges is to determine its probable origin for adequate surgical planning. Even though mostly all of these tumors are benign ovarian tumors, extraordinarily, malignant mural nodules may develop from the wall of these benign tumors, carrying an invariable unfavorable prognosis for the patient. This case highlights the importance of a correct diagnostic approach using ultrasound and abdominal computed tomography scans and confirming the diagnosis through a histopathologic examination. The treatment for these cases is surgical resection and posterior oncological treatment if needed. This case shows how timely treatment is one of the principal determinators of morbidity and mortality.

Surgical Excision of an Extratesticular Anaplastic Carcinoma in a Variable Kingsnake (Lampropeltis mexicana).

An adult male variable kingsnake (Lampropeltis mexicana) was presented for examination due to a three-week history of anorexia and obvious body deformities. On objective examination the animal was in poor condition, and on palpation, an intracoelomic mass was noted approximately in the distal third of the body, cranial to the cloaca. In agreement with the owner, an exploratory celiotomy was planned and performed and the mass was surgically removed. Modified Wright-Giemsa stain impression smears were taken, which were consistent with an undifferentiated tumour. Histological examination revealed the presence of a solid proliferation composed of highly tubular anaplastic cells and abundant multinucleated cells. The neoplastic cells were positive for cytokeratin (AE1/AE3), but not for vimentin. Periodic acid-Schiff (PAS) staining revealed the presence of large granular cells, which can be identified as the characteristic cells of the efferent ducts. Based on the morphological and immunohistochemical findings, the diagnosis of extratesticular anaplastic carcinoma was made. To the authors' knowledge, this type of neoplasm has never been reported in the male genital apparatus of snakes.

Clinicopathological profile and management of thyroid carcinoma: a Sub-Saharan country experience.

BACKGROUND: In Sudan, there is limited knowledge on the epidemiology, clinical characteristics and pathological patterns of thyroid cancer. To address this shortcoming, we studied the clinical, pathological and treatment patterns of thyroid cancer at the National Cancer Institute ‒ University of Gezira (NCI-UG), Sudan. METHODS: We performed a retrospective health facility-based study of patients with thyroid cancer who were treated at NCI-UG from January 2009 to December 2017. RESULTS: A total of 139 patients with thyroid cancer were identified during the study period. Tumors were more common among women (69%). Goiter was the main presenting symptom (85%). The most common type of thyroid cancer was follicular carcinoma (41%), followed by papillary carcinoma (24%), then anaplastic carcinoma (20%). The mean age of the women was 56.3 years (SD ± 14.7), compared to 52.5 years (SD ± 16.6) for the men. The frequencies of stage I, II, III, and IV were 17%, 22%, 16%, and 45%, respectively. Different types of thyroidectomies were performed in 79% of the cases, lobectomy in 4%, and no surgery in 17%. Only 28% of the cases received radioactive iodine. Palliative chemotherapy and radiotherapy were prescribed to 17% and 37% of the cases, respectively. CONCLUSION: Thyroid cancer is more prevalent among women and most patients present at later stages. The dominance of follicular type suggests that the majority of this population is iodine-deficient.

Anaplastic (undifferentiated) carcinoma of pancreas, an uncommon variant: Diagnosed on endoscopic-guided fine needle aspiration.

Anaplastic carcinoma of pancreas (ACP) are rare pancreatic neoplasms. They are well known to be associated with more aggressive tumor behavior and less favorable prognosis than usual pancreatic ductal adenocarcinoma. Endoscopic-guided fine needle aspiration (EUS-FNA) is now a widely accepted modality in diagnosis of pancreatic lesions. However, only a few reports are available describing cytological features of anaplastic carcinoma. Here, we report two cases of ACP diagnosed on EUS-FNA.

A mural nodule of anaplastic carcinoma with sarcomatoid differentiation in a background of ovarian borderline mucinous cystadenoma.

Ovarian mucinous cystic tumours with mural nodules are rare tumours of the ovary that are often missed out during diagnosis. They are classified under the ovarian mucinous surface epithelial-stromal tumours. These mural nodules can be sarcoma-like (benign), anaplastic carcinoma, sarcomas, or mixed malignant (carcinosarcoma). However, very few cases of anaplastic malignant mural nodules have been reported. Here, we present a case of a borderline ovarian mucinous cystadenoma with anaplastic mural nodule that has sarcomatoid differentiation, in a 39-year-old woman who presented with a 1-year history of progressive abdominal swelling and pain. There were intraoperative findings of huge right ovarian cystic tumour with omental and umbilical deposits. Differential diagnosis of possible germ cell tumours, vascular tumours, melanoma, sarcoma and sarcoma-like nodules were ruled out with routine histology (Haematoxylin & Eosin), histochemical (reticulin) and immunohistochemical stains (CK AE1/3+, CD30+, AFP-, HCG-, EMA-, S100 protein-, CD31-, and CD34-) and the final diagnosis of a mural nodule of anaplastic carcinoma with sarcomatoid differentiation in a borderline ovarian mucinous cystadenoma established. Unfortunately, due to the aggressive nature of the tumour and disease progression, the patient passed on a few months after the surgery. This rare tumour, especially the ones with anaplastic carcinoma or mixed tumours, usually has an aggressive clinical course with most patients presenting late when the disease is advanced with poor clinical outcomes as is seen with the index patient. A high index of suspicion of this tumour with early detection and a multidisciplinary approach to its management is advised.

Comprehensive review of undifferentiated carcinoma of the pancreas: from epidemiology to treatment.

Undifferentiated carcinoma (UC) of the pancreas is a rare subtype of pancreatic cancer displaying no definitive direction of differentiation. UC has been reported as a highly aggressive malignant neoplasm, with a median overall survival of <1 year, except for several surgical series. On the other hand, UC tissue sometimes contains non-neoplastic osteoclast-like giant cells (OGCs), and such cases have been reported to have relatively longer survival. Thus, the World Health Organization (WHO) classification histologically distinguishes UC with OGCs (UCOGCs) from UC, and UCs were subclassified into three subtypes: anaplastic UC, sarcomatoid UC and carcinosarcoma. However, still less is known about UC due to its rarity, and such situations lead to further difficulties in treatment for UC. To date, only surgical resection can offer curative treatment for patients with UC, and no clear evidence for chemotherapy exists for them. However, a retrospective cohort study and case reports showed that relatively promising results paclitaxel-containing regimens for treatment of patients with unresectable UC. Furthermore, high programmed cell death protein 1 expression has been reported in sarcomatoid UCs and UCOGCs, and promising responses to anti-programmed death-ligand 1 therapy have been described in case reports of UCOGCs. Recent advances in chemotherapeutic agents and molecular technologies are opening up the possibilities for expanded treatments.

Immunomorphological Patterns of Chaperone System Components in Rare Thyroid Tumors with Promise as Biomarkers for Differential Diagnosis and Providing Clues on Molecular Mechanisms of Carcinogenesis.

Hurthle cell (HC), anaplastic (AC), and medullary (MC) carcinomas are low frequency thyroid tumors that pose several challenges for physicians and pathologists due to the scarcity of cases, information, and histopathological images, especially in the many areas around the world in which sophisticated molecular and genetic diagnostic facilities are unavailable. It is, therefore, cogent to provide tools for microscopists to achieve accurate diagnosis, such as histopathological images with reliable biomarkers, which can help them to reach a differential diagnosis. We are investigating whether components of the chaperone system (CS), such as the molecular chaperones, can be considered dependable biomarkers, whose levels and distribution inside and outside cells in the tumor tissue could present a distinctive histopathological pattern for each tumor type. Here, we report data on the chaperones Hsp27, Hsp60, and Hsp90. They presented quantitative levels and distribution patterns that were different for each tumor and differed from those of a benign thyroid pathology, goiter (BG). Therefore, the reported methodology can be beneficial when the microscopist must differentiate between HC, AC, MC, and BG.

Genomic landscape and clinical features of rare subtypes of pancreatic cancer: analysis with the national database of Japan.

BACKGROUND: Special subtypes of pancreatic cancer, such as acinar cell carcinoma (ACC), adenosquamous carcinoma (ASC), and anaplastic carcinoma of the pancreas (ACP), are rare, and so data on them are limited. Using the C-CAT database, we analyzed clinical and genomic characteristics of patients with these and evaluated differences on comparison with pancreatic ductal adenocarcinoma (PDAC) patients. METHODS: We retrospectively reviewed data on 2691 patients with unresectable pancreatic cancer: ACC, ASC, ACP, and PDAC, entered into C-CAT from June 2019 to December 2021. The clinical features, MSI/TMB status, genomic alterations, overall response rate (ORR), disease control rate (DCR), and time to treatment failure (TTF) on receiving FOLFIRINOX (FFX) or GEM + nab-PTX (GnP) therapy as first-line treatment were evaluated. RESULTS: Numbers of patients with ACC, ASC, ACP, and PDAC were 44 (1.6%), 54 (2.0%), 25 (0.9%), and 2,568 (95.4%), respectively. KRAS and TP53 mutations were prevalent in ASC, ACP, and PDAC (90.7/85.2, 76.0/68.0, and 85.1/69.1%, respectively), while their rates were both significantly lower in ACC (13.6/15.9%, respectively). Conversely, the rate of homologous recombination-related (HRR) genes, including ATM and BRCA1/2, was significantly higher in ACC (11.4/15.9%) than PDAC (2.5/3.7%). In ASC and ACP, no significant differences in ORR, DCR, or TTF between FFX and GnP were noted, while ACC patients showed a trend toward higher ORR with FFX than GnP (61.5 vs. 23.5%, p = 0.06) and significantly more favorable TTF (median 42.3 vs. 21.0 weeks, respectively, p = 0.004). CONCLUSIONS: ACC clearly harbors different genomics compared with PDAC, possibly accounting for differences in treatment efficacy.

Anaplastic thyroid carcinoma:a clinicopathological study of 15 cases / 临床与实验病理学杂志

Purpose To investigate and summarize the clinicopathological features,immunophenotype,diagnosis and differential diagnosis of anaplastic thyroid carcinoma(ATC).Methods The clinicopathological features and follow-up data of 15 patients with ATC were reviewed and retrospectively ana-lyzed,and the histological features,immunophenotypic,and molecular features were observed.Results There were 8 males and 7 females with a mean age of 63.5 years.The largest tumor diameter was 45.9 mm(range,20-73 mm).Macroscopically,the tumors appeared nodular or lobulated,mostly firm to hard,with a cut surface of gray-white or gray-yellow in color,and were accompanied by hemorrhage,necrosis,and cystic changes.Mi-croscopically,the tumor exhibited diverse structures and cellular morphology mainly composed of epithelioid,spindle,multinu-cleated giant cells,rarely rhabdoid morphology(2 cases)and heterologous osteosarcomtoid differentiation(1 case).Two cases showed squamous cell carcinoma morphology as well.Among them,there were pure ATC in 11 cases while three cases had mixed papillary thyroid carcinoma components and one case had coexisting high-grade differentiated thyroid carcinoma compo-nent.Cervical lymph node metastasis was present in 6 cases.CK(AE1/AE3)expression was observed in 80%of the cases while PAX8 expression was seen in53.3%.Varying degrees of BRAF(VE1)expression were found in 42.9%whereas weak focal TTF-1 expression occurred only in two cases;and all cases did not express TG.Overall,genetic testing was performed in 8 cases(53.3%).The TP53 gene was the most frequently muta-ted gene(5/8,62.5%),followed by the RAS(3/8,37.5%)and BRAF(3/8,37.5%)genes,while the TERT combined with PIK3CA gene was mutated in only one case.Moreover,multiple gene mutations occurred simultaneously in five cases.Of the total fourteen patients who underwent follow-up,the mean and median survival times were 13.9 and 5.0 months,respec-tively.The disease-specific mortality rate reached 78.6%.Conclusion ATC is extremely rare,displaying unique histolog-ical characteristics,often accompanied by various gene muta-tions.It has a poor prognosis;therefore,establishing a defini-tive pathological diagnosis provides valuable evidence for predic-ting patient outcomes and guiding clinical management.

Defferential diagnosis and prognostic significance of squamous cell components in papillary thyroid carcinoma / 临床与实验病理学杂志

Purpose To investigate the diagnostic criteria and prognostic significance of squamous cell components in pa-pillary thyroid carcinoma(PTC).Methods Twenty-three cases of PTC containing squamous cell components were collect-ed,and pathological sections were reviewed.p40,CK5/6,Ki-67,BRAF V600E,p53,PD-L1(22C3),PAX8,and CD10,markers related to diagnosis,prognosis,and treatment,were de-tected by immunohistochemistry.Histological characteristics and immunophenotype of squamous cell components were comprehen-sively evaluated.The squamous cell components were classified histologically.The relationship between squamous cell classifica-tion and clinicopathological parameters,and their prognostic im-pact were analyzed.Results The squamous cell components were divided into squamous differentiation(19 cases)and ana-plastic carcinoma(4 cases).In the latter,the squamous cell components were diffusely distributed in sheets;the cell atypia was moderate to severe;and the Ki-67 index was at least 30%.High expression of p53 was found only in anaplastic carcinoma.Compared with squamous differentiation,anaplastic carcinoma had a larger diameter,higher BRAF V600E positive rate,high PD-L1 combined positive score,and extremely worse progression-free survival and overall survival.Squamous differentiation had inconspicuous impact on survival,and only one case relapsed af-ter secondary surgery.Conclusion The cell atypia,distribu-tion,maximum diameter,Ki-67 and p53 expression of squamous cell components are helpful in differentiating squamous compo-nents from anaplastic carcinoma.Positive BRAF V600E and PD-L1 expression suggest the feasibility of targeted therapy and im-munotherapy for anaplastic carcinoma.

Update on current diagnosis and management of anaplastic thyroid carcinoma.

Well-differentiated thyroid carcinoma has a favorable prognosis with a 5-year survival rate of over 95%. However, the undifferentiated or anaplastic type accounting for < 0.2%, usually in elderly individuals, exhibits a dismal prognosis with rapid growth and disappointing outcomes. It is the most aggressive form of thyroid carcinoma, with a median survival of 5 mo and poor quality of life (airway obstruction, dysphagia, hoarseness, persistent pain). Early diagnosis and staging are crucial. Diagnostic tools include biopsy (fine needle aspiration, core needle, open surgery), high-resolution ultrasound, computed tomography, magnetic resonance imaging, [(18)F]fluoro-D-glucose positron emission tomo-graphy/computed tomography, liquid biopsy and microRNAs. The BRAF gene (BRAF-V600E and BRAF wild type) is the most often found molecular factor. Others include the genes RET, KRAS, HRAS, and NRAS. Recent management policy is based on surgery, even debulking, chemotherapy (cisplatin or doxorubicin), radiotherapy (adjuvant or definitive), targeted biological agents and immunotherapy. The last two options constitute novel hopeful management modalities improving the overall survival in these otherwise condemned patients. Anti-programmed death-ligand 1 antibody immunotherapy, stem cell targeted therapies, nanotechnology achievements and artificial intelligence imple-mentation provide novel promising alternatives. Genetic mutations determine molecular pathways, thus indicating novel treatment strategies such as anti-BRAF, anti-vascular endothelial growth factor-A, and anti-epidermal growth factor receptor. Treatment with the combination of the BRAF inhibitor dabrafenib and the MEK inhibitor trametinib has been approved by the Food and Drug Administration in cases with BRAF-V600E gene mutations and is currently the standard care. This neoadjuvant treatment followed by surgery ensures a two-year overall survival of 80%. Prognostic factors for improved outcomes have been found to be younger age, earlier tumor stage and radiation therapy. A multidisciplinary approach is necessary, and the therapeutic plan should be individualized based on surveillance and epidemiology end results.

Rapid recurrence of a ruptured mucinous borderline ovarian tumor harboring K-RAS mutation followed by progression into anaplastic carcinoma with TP53 mutation.

We describe the case of a young patient with a borderline mucinous ovarian tumor that progressed into ipsilateral ovarian anaplastic carcinoma in only 3 months with metastasis to the contralateral ovary and extensive spread in the pelvic and abdominal regions. The mucinous tumor harbored micro-foci of intraepithelial carcinoma, but no mural nodules, microinvasion, or invasive adenocarcinoma were detected. Notably, a rupture on the ovarian mass and low-grade pseudomyxoma peritonei were present. Next-generation sequencing identified an identical KRAS mutation in the mucinous tumor and anaplastic carcinoma, while the latter had KRAS gene amplification and CDKN2A, MPL and TP53 mutations. These findings indicate the anaplastic carcinoma might have arisen via recurrence, malignant transformation and dedifferentiation of the former low-grade mucinous tumor. We consider that the mass rupture and pseudomyxoma peritonei were high-risk factors for recurrence, while genetic mutations were key drivers of progression. Accordingly, such cases may benefit from active surgical treatment and early chemotherapy.

Ovarian mucinous tumor with mural nodules of anaplastic carcinoma: Three case reports.

BACKGROUND: Anaplastic carcinoma mural nodules in ovarian mucinous tumors are very rare. This study aimed to report the morphological characteristics, molecular detection results, clinical treatment and prognosis of three ovarian mucinous tumors with mural nodules of anaplastic carcinoma. CASE SUMMARY: The pathomorphological features, molecular detection results, clinical treatment and prognosis of anaplastic carcinoma mural nodules were described in three cases. In case 1, sarcoma-like mural nodules (SLMNs) coexisted with anaplastic carcinoma mural nodules. No mutation was found in mucinous tumors. KRAS mutation was found in anaplastic carcinoma nodules and heterotypic cells were found in SLMNs. In case 2, KRAS mutation occurred in the mucinous epithelium and BRAF mutation occurred in mural nodules. In case 3, both mural nodules and mucinous tumors had the same KRAS mutation and a morphological transition between them was observed. All three patients died within 2 years, whether receiving chemotherapy or not. CONCLUSION: Anaplastic carcinoma mural nodules may develop from dedifferentiation of mucinous tumors or are unrelated to mucinous tumors.

A case of osteoclastic variant of anaplastic thyroid carcinoma: Diagnostic and prognostic marker studies by cytology.

Anaplastic thyroid carcinoma is an infrequent, but aggressive fatal subtype of thyroid cancer. The osteoclastic variant of anaplastic carcinoma is a rare subtype of anaplastic carcinoma with rare cases reported in the literature. Molecular targeted therapies have emerged for the anaplastic carcinoma, necessitating accurate pathologic diagnosis with additional ancillary testing for directing clinical management. We present here the cytological diagnosis of an anaplastic thyroid carcinoma-osteoclastic variant on fine-needle aspiration (FNA), with emphasis on the novelty of utilizing the least invasive procedure (aspiration cytology) for rendering pathological diagnosis as well as identifying potential prognostic markers for targeted immunotherapy.

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.