Merkel cell polyomavirus oncoproteins induce microRNAs that suppress multiple autophagy genes.

Viruses can inhibit host autophagy through multiple mechanisms, and evasion of autophagy plays an important role in immune suppression and viral oncogenesis. Merkel cell polyomavirus (MCPyV) T-antigens are expressed and involved in the pathogenesis of a large proportion of Merkel cell carcinoma (MCC). Yet, how MCPyV induces tumorigenesis is not fully understood. Herein, we show that MCPyV T-antigens induce miR-375, miR-30a-3p and miR-30a-5p expressions, which target multiple key genes involved in autophagy, including ATG7, SQSTM1 (p62) and BECN1. In MCC tumors, low expression of ATG7 and p62 are associated with MCPyV-positive tumors. Ectopic expression of MCPyV small T-antigen and truncated large T-antigen (LT), but not the wild-type LT, resulted in autophagy suppression, suggesting the importance of autophagy evasion in MCPyV-mediated tumorigenesis. Torin-1 treatment induced cell death, which was attenuated by autophagy inhibitor, but not pan-caspase inhibitor, suggesting a potential role of autophagy in promoting cell death in MCC. Conceptually, our study shows that MCPyV oncoproteins suppress autophagy to protect cancer cells from cell death, which contribute to a better understanding of MCPyV-mediated tumorigenesis and potential MCC treatment.

Parafibromin immunostainings of parathyroid tumors in clinical routine: a near-decade experience from a tertiary center.

The cell division cycle 73 gene is mutated in familial and sporadic forms of primary hyperparathyroidism, and the corresponding protein product parafibromin has been proposed as an adjunct immunohistochemical marker for the identification of cell division cycle 73 mutations and parathyroid carcinoma. Here, we present data from our experiences using parafibromin immunohistochemistry in parathyroid tumors since the marker was implemented in clinical routine in 2010. A total of 2019 parathyroid adenomas, atypical adenomas, and carcinomas were diagnosed in our department, and parafibromin staining was ordered for 297 cases with an initial suspicion of malignant potential to avoid excessive numbers of false positives. The most common inclusion criteria for immunohistochemistry were marked tumor weight (146 cases) and/or fibrosis (77 cases) and/or marked pleomorphism (58 cases). In total, 238 cases were informatively stained, and partial or complete loss of nuclear parafibromin immunoreactivity was noted in 40 cases; 10 out of 182 adenomas (5%), 27 out of 46 atypical adenomas (59%), and 7 out of 10 carcinomas (70%), with positive and negative predictive values of 85 and 90%, respectively for the detection of atypical adenomas/carcinomas versus adenomas, and 18 and 98%, respectively for carcinomas versus atypical adenomas/adenomas. Male patients with high-proliferative tumors were overrepresented among cases with aberrant parafibromin immunohistochemistry, and carcinomas more frequently harbored parafibromin aberrancies than atypical adenomas and adenomas (p < 0.001). We conclude that parafibromin immunohistochemistry is a useful marker in the clinical routine when applied on a pre-selected material of cases, with positive immunoreactivity as a confident rule out marker of malignancy.

Regional differences in somatostatin receptor 2 (SSTR2) immunoreactivity is coupled to level of bowel invasion in small intestinal neuroendocrine tumors.

OBJECTIVE: Somatostatin receptor (SSTR) expression constitutes a pivotal cornerstone for accurate radiological detection and medical treatment of small intestinal neuroendocrine tumors (SI-NETs), and the development of somatostatin analogues for these purposes have revolutionized the clinical work-up. Previous assessments of SSTR isoform expression in SI-NETs have found correlations to overall prognosis and treatment response, however these analyses usually report overall tumoral immunoreactivity, and little is reported regarding histo-regional differences in expressional patterns. METHODS: Thirty-seven primary SI-NETs (WHO grade I, n=32 and WHO grade II, n=5) were collected and assessed for SSTR2 immunohistochemistry. Samples were stratified with regards to histological level of bowel infiltration and spread (mucosal region, muscularis propria region, subserosal region) and each of these tumoral regions was separately scored by SSTR2 staining localization (membrane, cytoplasmic), overall staining intensity and local staining differences within each region. RESULTS: SSTR2 immunoreactivity was progressively weaker as the tumor cells advanced through the small intestinal layers. This was exemplified by a reduction in the amount of tumor samples with strong SSTR2 expression in the deeper histological levels of the section; 56% of tumors displayed strong SSTR2 expression in the mucosal region, as compared to 29% and 30% of tumors within muscularis propria and subserosal layers, respectively. CONCLUSIONS: This observation indicates a down-regulation of SSTR2 expression as the tumors progress through the intestinal wall, which might signify underlying biological processes of importance for SI-NET invasion behavior.

Characterization of the mutational landscape of anaplastic thyroid cancer via whole-exome sequencing.

Anaplastic thyroid carcinoma (ATC) is a frequently lethal malignancy that is often unresponsive to available therapeutic strategies. The tumorigenesis of ATC and its relationship to the widely prevalent well-differentiated thyroid carcinomas are unclear. We have analyzed 22 cases of ATC as well as 4 established ATC cell lines using whole-exome sequencing. A total of 2674 somatic mutations (121/sample) were detected. Ontology analysis revealed that the majority of variants aggregated in the MAPK, ErbB and RAS signaling pathways. Mutations in genes related to malignancy not previously associated with thyroid tumorigenesis were observed, including mTOR, NF1, NF2, MLH1, MLH3, MSH5, MSH6, ERBB2, EIF1AX and USH2A; some of which were recurrent and were investigated in 24 additional ATC cases and 8 ATC cell lines. Somatic mutations in established thyroid cancer genes were detected in 14 of 22 (64%) tumors and included recurrent mutations in BRAF, TP53 and RAS-family genes (6 cases each), as well as PIK3CA (2 cases) and single cases of CDKN1B, CDKN2C, CTNNB1 and RET mutations. BRAF V600E and RAS mutations were mutually exclusive; all ATC cell lines exhibited a combination of mutations in either BRAF and TP53 or NRAS and TP53. A hypermutator phenotype in two cases with >8 times higher mutational burden than the remaining mean was identified; both cases harbored unique somatic mutations in MLH mismatch-repair genes. This first comprehensive exome-wide analysis of the mutational landscape of ATC identifies novel genes potentially associated with ATC tumorigenesis, some of which may be targets for future therapeutic intervention.

Primary aldosteronism: functional histopathology and long-term follow-up after unilateral adrenalectomy.

OBJECTIVES: To investigate the long-term outcome after unilateral adrenalectomy in patients with primary aldosteronism (PA) and to establish the role of functional pathology for the final diagnosis of aldosterone-producing adenoma (APA) or hyperplasia. DESIGN: A single-centre, retrospective cohort study in a hospital setting. PATIENTS: Consecutive patients with PA, n = 120, who underwent unilateral adrenalectomy between 1985 and 2010. Preoperative and postoperative data were analysed. To indicate the site of aldosterone secretion in the resected adrenal, we added functional methods to routine histopathology, using in situ hybridization and immunohistochemistry to detect the presence of enzymes needed for aldosterone (CYP11B2) and cortisol (CYP11B1, CYP17A1) synthesis. RESULTS: The median follow-up was 5 years and the cure rate of PA 91%. Hypertension was improved in 97% and normalized in 38%. Functional histopathology changed the final diagnosis from APA to hyperplasia in 6 cases (7%). Five of these had no expression of or staining for aldosterone synthase in the adenoma, but only in nodules in the adjacent cortex. All except one APA patient were cured of PA. They had lower preoperative serum potassium and higher 24-h urinary aldosterone than patients with hyperplasia. Among patients with hyperplasia 16 of 26 were cured. CONCLUSIONS: Most patients were cured of PA by unilateral adrenalectomy. Almost all noncured benefitted from the operation as the blood pressure improved. Functional histopathology proved helpful in the distinction between APA and hyperplasia, and we recommend that functional histopathology should be added to routine histopathology to improve the diagnostic evaluation and aid in tailoring the follow-up.

TERT promoter mutation as an early genetic event activating telomerase in follicular thyroid adenoma (FTA) and atypical FTA.

BACKGROUND: The telomerase reverse transcriptase (TERT) promoter mutations C228T and C250T have been found in many malignancies, including in thyroid carcinomas. However, it is unclear how early these mutations occur in thyroid tumorigenesis. METHODS: The study included primary tumors from 58 patients initially diagnosed with follicular thyroid adenoma (FTA), a benign entity, 18 with atypical FTA (AFTA) having an uncertain malignant potential, and 52 with follicular thyroid carcinoma (FTC). Sanger sequencing was used to investigate the mutational status of the TERT promoter. Telomere length and TERT messenger RNA (mRNA) expression were determined using quantitative polymerase chain reaction (PCR). Telomerase activity was assessed using a Telomerase PCR enzyme-linked immunosorbent assay kit. RESULTS: The C228T mutation was identified in 1 of 58 FTA (2%) and 3 of 18 AFTA (17%) samples. These 4 tumors all expressed TERT mRNA and telomerase activity, whereas the majority of C228T-negative adenomas lacked TERT expression (C228T versus wild-type, P = .008). The C228T mutation was associated with NRAS gene mutations (P = .016). The patient with C228T-mutated FTA later developed a scar recurrence and died of FTC, whereas none of the remaining 57 patients with FTA had recurrence. No recurrence occurred in 3 patients with AFTA who carried C228T during the follow-up period (36-285 months). Nine of the 52 FTCs (17%) exhibited the TERT mutation (8 of 9 C228T and 1 of 9 C250T), and the presence of the mutation was associated with shorter patient survival. CONCLUSIONS: TERT promoter mutations may occur as an early genetic event in thyroid follicular tumors that have not developed malignant features on routine histopathological workup.

Lowering apolipoprotein CIII delays onset of type 1 diabetes.

Serum levels of apolipoprotein CIII (apoCIII) are increased in type 1 diabetic patients, and when ß cells are exposed to these diabetic sera, apoptosis occurs, an effect abolished by an antibody against apoCIII. We have investigated the BB rat, an animal model that develops a human-like type 1 diabetes, and found that apoCIII was also increased in sera from prediabetic rats. This increase in apoCIII promoted ß-cell death. The endogenous levels of apoCIII were reduced by treating prediabetic animals with an antisense against this apolipoprotein, resulting in a significantly delayed onset of diabetes. ApoCIII thus serves as a diabetogenic factor, and intervention with this apolipoprotein in the prediabetic state can arrest disease progression. These findings suggest apoCIII as a target for the treatment of type 1 diabetes.

Copy number alterations in small intestinal neuroendocrine tumors determined by array comparative genomic hybridization.

BACKGROUND: Small intestinal neuroendocrine tumors (SI-NETs) are typically slow-growing tumors that have metastasized already at the time of diagnosis. The purpose of the present study was to further refine and define regions of recurrent copy number (CN) alterations (CNA) in SI-NETs. METHODS: Genome-wide CNAs was determined by applying array CGH (a-CGH) on SI-NETs including 18 primary tumors and 12 metastases. Quantitative PCR analysis (qPCR) was used to confirm CNAs detected by a-CGH as well as to detect CNAs in an extended panel of SI-NETs. Unsupervised hierarchical clustering was used to detect tumor groups with similar patterns of chromosomal alterations based on recurrent regions of CN loss or gain. The log rank test was used to calculate overall survival. Mann-Whitney U test or Fisher's exact test were used to evaluate associations between tumor groups and recurrent CNAs or clinical parameters. RESULTS: The most frequent abnormality was loss of chromosome 18 observed in 70% of the cases. CN losses were also frequently found of chromosomes 11 (23%), 16 (20%), and 9 (20%), with regions of recurrent CN loss identified in 11q23.1-qter, 16q12.2-qter, 9pter-p13.2 and 9p13.1-11.2. Gains were most frequently detected in chromosomes 14 (43%), 20 (37%), 4 (27%), and 5 (23%) with recurrent regions of CN gain located to 14q11.2, 14q32.2-32.31, 20pter-p11.21, 20q11.1-11.21, 20q12-qter, 4 and 5. qPCR analysis confirmed most CNAs detected by a-CGH as well as revealed CNAs in an extended panel of SI-NETs. Unsupervised hierarchical clustering of recurrent regions of CNAs revealed two separate tumor groups and 5 chromosomal clusters. Loss of chromosomes 18, 16 and 11 and gain of chromosome 20 were found in both tumor groups. Tumor group II was enriched for alterations in chromosome cluster-d, including gain of chromosomes 4, 5, 7, 14 and gain of 20 in chromosome cluster-b. Gain in 20pter-p11.21 was associated with short survival. Statistically significant differences were observed between primary tumors and metastases for loss of 16q and gain of 7. CONCLUSION: Our results revealed recurrent CNAs in several candidate regions with a potential role in SI-NET development. Distinct genetic alterations and pathways are involved in tumorigenesis of SI-NETs.

Anaplastic carcinoma of the thyroid gland: treatment and outcome over 13 years at one institution.

BACKGROUND: Anaplastic thyroid carcinoma (ATC) is a highly aggressive malignancy of the thyroid gland. Patients at our institution are treated with external radiotherapy up to 46 Gray (Gy) and low-dose doxorubicin prior to surgery. We retrospectively evaluated the outcome of ATC patients over a 13-year period. METHODS: Clinical, histopathological, and follow-up data for 59 patients diagnosed between 1997 and 2010 were collected and analyzed. RESULTS: Median age at diagnosis was 77 years. Female-male ratio was 2.5:1. Median survival from time of diagnosis was 3.3 months. Thirty-six patients completed the treatment protocol (including surgery), of whom one succumbed due to local tumor growth. In multivariate analysis, the only factor significantly associated with longer survival among operated patients was absence of metastases at diagnosis (P = 0.031). No impact on survival time was found for gender, extent of surgical resection, and absence of extrathyroidal invasion. CONCLUSIONS: Despite aggressive treatment, survival rates in ATC patients remain low. Locoregional control is feasible for most patients, underscoring the importance of an intense, multimodal treatment regimen. Further oncological intervention is of crucial importance to achieve a better prognosis for ATC patients.

Metastatic Neuroendocrine Neoplasms of Unknown Primary: Clues from Pathology Workup.

Neuroendocrine neoplasms (NENs) are diverse tumors arising in various anatomical locations and may therefore cause a variety of symptoms leading to their discovery. However, there are instances in which a NEN first presents clinically as a metastatic deposit, while the associated primary tumor is not easily identified using conventional imaging techniques because of small primary tumor sizes. In this setting (which is referred to as a "NEN of unknown primary"; NEN-UP), a tissue biopsy is often procured to allow the surgical pathologist to diagnose the metastatic lesion. If indeed a metastatic NEN-UP is found, several clues can be obtained from morphological assessment and immunohistochemical staining patterns that individually or in concert may help identify the primary tumor site. Herein, histological and auxiliary analyses of value in this context are discussed in order to aid the pathologist when encountering these lesions in clinical practice.

Prognostic Utility of the Ki-67 Labeling Index in Follicular Thyroid Tumors: a 20-Year Experience from a Tertiary Thyroid Center.

Follicular thyroid tumors pose a diagnostic challenge on the preoperative level, as the discrimination between follicular thyroid carcinoma (FTC) and adenoma (FTA) demands careful histopathological investigation. Moreover, prognostication of FTCs is mostly based on tumor size and extent of invasive properties, while immunohistochemical markers pinpointing high-risk cases are lacking. We have routinely established a Ki-67 labeling index for follicular thyroid tumors since 1999. To assess the potential value of Ki-67 as an adjunct tool to (1) correctly separate FTCs from FTAs and (2) help identify poor-prognosis FTCs, we collected histopathological and clinical data from 818 follicular thyroid tumors with a histological Ki-67 labeling index established in clinical routine practice (516 FTAs, 252 FTCs, and 50 follicular thyroid tumors of uncertain malignant potential (FT-UMPs)). The Ki-67 labeling index was higher in FTCs (mean 5.8%) than in FTAs (mean 2.6%) (P < 0.001), and a receiver operating characteristic curve analysis revealed a cut-off value of 4% to separate FTC from FTA with a sensitivity and specificity of 65% and 83%, respectively. Similarly, a Ki-67 labeling index above 4% was found to identify FTCs that later metastasized from clinically indolent FTCs with a sensitivity and specificity of 80% and 48%, respectively. Ki-67 constituted an independent predictor of future FTC metastases/recurrence and death of disease, and a value > 4% was a reliable prognostic marker within individual pT staging groups. We conclude that Ki-67 is a potentially valuable marker for the prognostication of FTCs, and future implementation in the histopathological assessments of follicular thyroid tumors could be beneficial if reproduced in international series.

Altered expression of the IGF2­H19 locus and mitochondrial respiratory complexes in adrenocortical carcinoma.

Abnormalities of the insulin­like growth factor 2 (IGF2)­H19 locus with the overexpression of IGF2 are frequent findings in adrenocortical carcinoma (ACC). The present study assessed the expression of RNAs and microRNAs (miRNAs/miRs) from the IGF2­H19 locus using PCR­based methods in ACC and adrenocortical adenoma (ACA). The results were associated with proteomics data. IGF2 was overexpressed in ACC, and its expression correlated with that of miR­483­3p and miR­483­5p hosted by IGF2. The downregulated expression of H19 in ACC compared to ACA correlated with miR­675 expression hosted by H19. Several proteins exhibited an inverse correlation in expression and were predicted as targets of miR­483­3p, miR­483­5p or miR­675. Subsets of these proteins were differentially expressed between ACC and ACA. These included several proteins involved in mitochondrial metabolism. Among the mitochondrial respiratory complexes, complex I and IV were significantly decreased in ACC compared to ACA. The protein expression of NADH:ubiquinone oxidoreductase subunit C1 (NDUFC1), a subunit of mitochondrial respiratory complex I, was further validated as being lower in ACC compared to ACA and normal adrenals. The silencing of miR­483­5p increased NDUFC1 protein expression and reduced both oxygen consumption and glycolysis rates. On the whole, the findings of the present study reveal the dysregulation of the IGF2­H19 locus and mitochondrial respiration in ACC. These findings may provide a basis for the further understanding of the pathogenesis of ACC and may have potential values for diagnostics and treatment.

Perithyroidal Salivary Gland Acinic Cell Carcinoma: Morphological and Molecular Attributes of a Unique Lesion.

Rarely, salivary gland tumors such as mucoepidermoid carcinoma, mammary analogue secretory carcinoma and mucinous carcinoma arise as primary tumors from ectopic or metaplastic salivary gland tissue adjacent to or within the thyroid gland. We report for the first time a case of primary salivary acinic cell carcinoma (AcCC) adjacent to the thyroid gland in a 71-year-old female patient with Crohns disease and a previous history of malignant melanoma. Following the development of a nodule adjacent to the left thyroid lobe, a fine-needle aspiration biopsy was reported as consistent with a follicular lesion of undetermined significance (Bethesda III). A left-sided hemithyroidectomy was performed. A circumscribed lesion measuring 33 mm was noted adjacent to the thyroid and trapping parathyroid, it was composed of solid nests and glands with microcystic and follicular patterns. The tumor was negative for thyroid, parathyroid and paraganglioma markers, but positive for pan-cytokeratins, CK7, CD10, CD117, androgen receptor and HNF-beta. A metastasis of a thyroid-like renal cell carcinoma was suspected but ruled out, and the patient had no evident lesions on extensive radiology of the urogenital, pulmonary and GI tracts. Based on the morphology, a diagnosis of AcCC was suggested, and confirmed with DOG1 and PAS-diastase staining. Molecular analyses pinpointed a constitutional ASXL1 variant of uncertain significance, but no fusion events. The patient had no radiological or clinical evidence of parotid, submandibular or sublingual tumors postoperatively, and the excised lesion was therefore assumed to be a primary tumor. We here detail the morphological and immunophenotypic profile of this previously undescribed perithyroidal tumor.

Nuclear-specific accumulation of telomerase reverse transcriptase (TERT) mRNA in TERT promoter mutated follicular thyroid tumours visualised by in situ hybridisation: a possible clinical screening tool?

AIMS: Upregulation of the telomerase reverse transcriptase (TERT) gene is a frequent finding in follicular thyroid carcinomas (FTCs) with metastatic features. The augmented expression is usually caused by TERT promoter mutations. As TERT protein immunohistochemistry might not correlate to TERT mRNA levels in follicular thyroid tumours, we therefore sought to determine if visualisation of TERT mRNA through in situ hybridisation could highlight high-risk cases. METHODS: We collected formalin-fixated paraffin-embedded tissues from 26 follicular thyroid tumours; 7 FTCs, 2 follicular thyroid tumours of uncertain malignant potential (FT-UMPs) and a single Hürthle cell carcinoma with established TERT promoter mutations and gene expression, as well as 16 FTCs with no TERT gene aberrancy or gene expression, and assessed them using RNA Scope in situ hybridisation (ISH) and TERT probes targeting the two main TERT transcripts (TERT1 and TERT2). RESULTS: TERT 1 and/or 2 mRNA was found by ISH in 8/10 cases with established promoter mutations and mRNA expression, whereas all 16 cases without TERT gene aberrancies or gene expression were negative (Fisher's exact p<0.001). Strikingly, TERT mRNA was visualised in the nuclear compartment only, thereby corroborating earlier studies suggesting a non-conventional role for TERT in tumour biology. Moreover, TERT mRNA expression was scattered across the tissue sections and only found in a few percentages of tumour nuclei. CONCLUSIONS: TERT mRNA seems to be focally expressed and localised exclusively to the nucleus in TERT promoter mutated follicular thyroid tumours, possibly reflecting a true biological and unorthodox phenomenon worthy of further investigations.

Clinical Routine Application of the Second-generation Neuroendocrine Markers ISL1, INSM1, and Secretagogin in Neuroendocrine Neoplasia: Staining Outcomes and Potential Clues for Determining Tumor Origin.

Neuroendocrine neoplasms (NENs) have traditionally been identified via expression of proteins associated to the regulation of secretory vesicles and granules. We report the clinical usage of the "second-generation" proteins ISL LIM homeobox 1 (ISL1), INSM transcriptional repressor 1 (INSM1), and secretagogin (SECG) as immunohistochemical markers of neuroendocrine differentiation since their introduction in clinical routine and compare the results with the established proteins chromogranin A (CGA) and synaptophysin (SYP). In total, 161 tumors, including 139 NENs and 22 "non-NENs" (unrelated tumors with an initial suspicion of NEN), were informatively stained for ISL1, and subsets were also interrogated for INSM1 and/or SECG. Diffuse or focal positive immunoreactivity was noted for ISL1 in 91/139 NENs (65%) and in 6/22 (27%) non-NENs, for INSM1 in 76/85 NENs (89%) and in 2/5 (40%) non-NENs, and for SECG in 49 out of 64 NENs (77%) and in 0/5 non-NENs (0%). Generally, ISL1, INSM1, and SECG exhibited sensitivities in line with or slightly below that of CGA and SYP-largely attributable to tissue-specific patterns regarding tumoral origin. Moreover, for pancreatic and small intestinal NENs, the two largest subgroups, ISL1 staining results were consistent irrespectively of tumor source and WHO grade. We verify previously suggested immunohistochemical schemes of neuroendocrine markers of first- and second-generations to facilitate the diagnostic process for NENs and confirm that the second-generation neuroendocrine markers display tissue-specific patterns. We therefore recommend their implementation in tertiary endocrine pathology centers, not least to aid in the identification of primary tumors when analyzing metastases.

Lipoadenoma of the Parathyroid Gland: Characterization of an Institutional Series Spanning 28 Years.

Parathyroid lipoadenomas (PLAs) are rare tumors, and case descriptions are limited, < 80 to date. As a consequence, scarce information regarding the etiology of these enigmatic lesions is available. We searched our departmental pathology database for PLAs diagnosed between 1992 and 2020, reexamined the histology of each case, and recorded clinical parameters from the patients' medical charts. As the diagnostic criteria of this lesion vary over this time period, we defined PLA as an enlarged parathyroid gland with > 50% fat on histologic examination with preoperative evidence of primary hyperparathyroidism (PHPT). A total of 8 bona fide PLA cases and 2 equivocal PLAs (close to 50% fat) were included. As approximately 4000 conventional parathyroid adenomas were diagnosed at our department during the same time interval, the prevalence of PLA was 0.20%. PLA patients were predominately female (63%) and presented with classical PHPT-related symptoms. Majority of cases were successfully located preoperatively and had an average tumor weight of 445 mg. Histologically, all PLAs consisted of > 50% mature adipose tissue, except a single case with brown fat. Of note, PLA patients exhibited a body mass index in line with PHPT patients in general, but a relatively high, near-significant prevalence of arterial hypertension was observed when compared to tumors with less fat (P = 0.0584). Future studies on this finding might be warranted. To summarize, we present one of the largest institutional PLA case series to date, and conclude that PLAs are rare, sporadic tumors mirroring many clinical aspects of conventional adenomas-with a potential coupling to hypertension worthy of follow-up studies.

Loss of expression for the Wnt pathway components adenomatous polyposis coli and glycogen synthase kinase 3-beta in parathyroid carcinomas.

The development of parathyroid carcinoma has been associated with inactivating mutations of the Hyperparathyroidism type 2 (HRPT2) gene encoding parafibromin, a member of the human RNA Polymerase II-Associated Factor Complex (hPAF) and functionally linked to the Wingless type (Wnt) pathway. In this study, we characterized the expression of Wnt pathway molecules in parathyroid benign and malignant tumors. Tumors were investigated by immunohistochemistry supplemented with Western blot analyses using monoclonal antibodies. The study comprised 13 tumors from 12 cases of unequivocal parathyroid carcinoma, 18 cases of parathyroid adenoma, as well as non-tumorous parathyroid tissue. Adenomatous polyposis coli (APC) was uniformly expressed in non-tumorous parathyroid tissue and adenomas, but absent in carcinomas from 9 of 12 patients (75%). Expression of glycogen synthase kinase 3-beta (GSK3-beta) was lost in 4/12 carcinomas and in 1/18 adenomas. The loss of APC and GSK3-beta did not lead to augmentation of the Wnt target protein cyclin D1 or the Wnt oncoprotein beta-catenin. Active beta-catenin showed cytoplasmic and nuclear expression in all non-tumorous tissues and tumors. Loss of APC immunoreactivity was significantly associated with parathyroid carcinoma as compared to adenomas (p<0.001), giving a high specificity (100%) and sensitivity (75%) for the detection of parathyroid malignancy. The results suggest the involvement of Wnt-pathway members APC and GSK3-beta in parathyroid carcinoma development. In addition, APC immunohistochemistry could become a useful tool for improved recognition of parathyroid carcinoma together with immunohistochemistry for parafibromin and proliferation index. Furthermore, the involvement of APC related pathways in the disease development opens possibilities to explore therapeutic routes complementary to surgery.

Diagnostic and prognostic potential of MIB-1 proliferation index in thyroid fine needle aspiration biopsy.

Fine needle aspiration biopsy (FNAB) is the preferred technique for the initial diagnostic evaluation of thyroid lesions, which nevertheless poses a diagnostic challenge for all clinicians involved. The latter necessitates the use of molecular markers on thyroid cytology. MIB-1 is a molecular marker already used in the cytological evaluation of various tumors. In this study, we assessed whether MIB-1 proliferation index adds diagnostic information to the conventional cytological analysis of thyroid nodules and prognostic information in thyroid cancers. MIB-1 index for various thyroid lesions was retrospectively reviewed in a series of 504 patients. Furthermore, the prognostic value of MIB-1 index was investigated for 183 of the patients with papillary thyroid cancer (PTC). MIB-1 index was significantly higher in anaplastic thyroid cancer (ATC) compared to other tumor types (p<0.01). No significant difference in MIB-1 index was observed between thyroid adenomas and follicular carcinomas. In PTC, MIB-1 index equal to or >4% was found to be an independent factor significantly associated with higher risk of distant metastasis and disease-related mortality (p<0.05). Conclusively, this study shows that preoperative MIB-1 index assessment in FNAB of thyroid nodules offers little diagnostic information as far as follicular tumors are concerned. In cases of PTC, though, MIB-1 may serve as a prognostic indicator of disease spreading and poor survival and hence influence the planning of the overall treatment scheme.

Clear Cell Variant of Papillary Thyroid Carcinoma With Associated Anaplastic Thyroid Carcinoma: Description of an Extraordinary Case.

Clear cell change is a rare observation in thyroid cancer, resulting from aberrant cytoplasmic accumulation of lipids, glycogen, or thyroglobulin in the tumor cells. The phenomenon is most common for follicular thyroid neoplasia, with no definite coupling to patient outcome. The clear cell variant of papillary thyroid carcinoma (ccPTC) is even more infrequent-making conclusions regarding prognosis difficult. Single reports describe distant metastases of ccPTCs as well as co-occurrence with anaplastic thyroid carcinoma (ATC). In this report, a case of a therapy-resistant ccPTC dedifferentiating into an ATC is characterized from morphological and immunohistochemical standpoints. The patient was a 79-year-old female presenting with a 45-mm nodule in her right thyroid lobe. A first round of cytology raised the suspicion of PTC, but a repeated biopsy verified an ATC diagnosis. Neoadjuvant doxorubicin and external irradiation therapy was administered, and the patient developed lung metastases concomitantly. A palliative lobectomy was performed, and the final diagnosis was a ccPTC with focal dedifferentiation into an ATC. Intriguingly, the ccPTC component was viable and dominated the lesion. The clear cell morphology stemmed from an accumulation of glycogen, while the anaplastic component was devoid of evident clear cell changes. The case is one of exceedingly few descriptions of a ccPTC that dedifferentiates to an ATC, suggesting that this PTC subtype is not without potential for development of a highly lethal tumor component. Moreover, the partial lack of response to neoadjuvant therapy suggests a possible underlying resistance to aggressive treatment modalities in this particular case.

Clear Cell Variant of a Follicular Thyroid Tumor With Uncertain Malignant Potential: A Case Report.

Follicular neoplasms of the thyroid gland are most often characterized by follicular-patterned thyrocytes with a neutrally stained cytoplasm, while a minority of cases present with oncocytic differentiation (Hürthle cell tumors). Exceedingly rare variants with a clear cell phenotype have also been reported, both as clear cell follicular thyroid adenomas (ccFTAs) and clear cell follicular carcinomas (ccFTCs). We present a patient with a 30-mm lesion in the thyroid isthmus in which the preoperative cytology proposed a follicular tumor. On postoperative histopathological evaluation, the tumor surprisingly displayed uniform clear-cell differentiation. No nuclear features suggestive of papillary thyroid carcinoma were observed, and differential diagnoses such as medullary thyroid carcinoma, metastatic renal cell, and parathyroid carcinoma were ruled out. The histological investigation revealed intracapsular collections of tumor cells displaying a debatable relation to the surrounding capsule and blood vessels, and the final diagnosis was a follicular tumor of uncertain malignant potential (FT-UMP) as defined by the WHO 2017 classification. As subsets of FT-UMPs with TERT promoter mutations do recur as advanced malignant tumors, a sequencing analysis was undertaken but could not identify TERT promoter mutations at position C228 or C250. To our knowledge, no previous literature has described a clear cell phenotype in an FT-UMP. We therefore advocate that endocrine pathologists should be aware of this entity in addition to ccFTAs and ccFTCs.