Basal and stimulated calcitonin for the diagnosis of medullary thyroid cancer: updated thresholds and safety assessment.

PURPOSE: Reliable cut-offs for basal (bCT) and calcium stimulated calcitonin (casCT) are needed for an early and accurate diagnosis of medullary thyroid cancer (MTC). PATIENTS AND METHODS: Fifty-four new patients with nodular goiter were enrolled and analysed together with those previously published by our group for a total of 135 cases. bCT and casCT were measured by a highly sensitive method and the results compared with histological findings. In a subgroup of patients, cardiac rhythm was recorded before and during the calcium test. RESULTS: In both females (F) and males (M), there was a significant correlation between tumor size and bCT levels (P < 0.001). The receiver operating characteristic plot analyses showed that, for bCT, the new cut-off points able to separate non-MTC from MTC patients were > 30 (F) and > 34 pg/mL (M), whereas the best casCT thresholds were > 79 (F) and > 466 pg/mL (M). bCT was shown to harbour a high accuracy, though some cases were diagnosed only upon stimulation test. Importantly, combining bCT, below or above the cut-offs, with casCT above the cut-offs, all the MTC cases were correctly identified. A reversible sinus bradycardia was observed in 9% of cases during the test. CONCLUSIONS: Refined cut-offs for bCT and casCT in patients with nodular goiter are reported. Sensitive bCT was shown to have a high accuracy, but the combination with casCT data was needed to identify all MTC cases. The reliability and safety of calcium test strongly favour the routine use of CT determination in nodular thyroid disease.

Molecular markers for the classification of cytologically indeterminate thyroid nodules.

BACKGROUND: The diagnosis of indeterminate lesions of the thyroid is a challenge in cytopathology practice. Indeed, up to 30% of cases lack the morphological features needed to provide definitive classification. Molecular tests have been developed to assist in the diagnosis of these indeterminate cases. The first studies dealing with the preoperative molecular evaluation of FNA samples focused on the analysis of BRAFV600E or on the combined evaluation of two or three genetic alterations. The sensitivity of molecular testing was then improved through the introduction of gene panels, which became available for clinical use in the late 2000s. Two different categories of molecular tests have been developed, the 'rule-out' methods, which aim to reduce the avoidable treatment of benign nodules, and the 'rule-in' tests that have the purpose to optimize surgical management. The genetic evaluation of indeterminate thyroid nodules is predicted to improve patient care, particularly if molecular tests are used appropriately and with the awareness of their advantages and weaknesses. The main disadvantage of these tests is the cost, which makes them rarely used in Europe. To overcome this limitation, customized panels have been set up, which are able to detect the most frequent genetic alterations of thyroid cancer. CONCLUSIONS: In the present review, the most recent available versions of commercial molecular tests and of custom, non-commercial panels are described. Their characteristics and accuracy in the differential diagnosis of indeterminate nodules, namely Bethesda classes III (Atypical follicular lesion of undetermined significance, AUS/FLUS) and IV (Suspicious for follicular neoplasm, FN/SFN) are fully analyzed and discussed.

Italian consensus on diagnosis and treatment of differentiated thyroid cancer: joint statements of six Italian societies.

BACKGROUND: Thyroid nodules are a common clinical problem, and differentiated thyroid cancer is becoming increasingly prevalent. METHODS: Six scientific Italian societies entitled to cure thyroid cancer patients (the Italian Thyroid Association, the Medical Endocrinology Association, the Italian Society of Endocrinology, the Italian Association of Nuclear Medicine and Molecular Imaging, the Italian Society of Unified Endocrine Surgery and the Italian Society of Anatomic Pathology and Diagnostic Cytology) felt the need to develop a consensus report based on significant scientific advances occurred in the field. OBJECTIVE: The document includes recommendations regarding initial evaluation of thyroid nodules, clinical and ultrasound criteria for fine-needle aspiration biopsy, initial management of thyroid cancer including staging and risk assessment, surgical management, radioiodine remnant ablation, and levothyroxine therapy, short-term and long-term follow-up strategies, and management of recurrent and metastatic disease. The objective of this consensus is to inform clinicians, patients, researchers, and health policy makers about the best strategies (and their limitations) relating to the diagnosis and treatment of differentiated thyroid cancer.

Thyroid volume and serum calcitonin changes during pregnancy.

BACKGROUND: Pregnancy has a profound impact on thyroid homeostasis which results in change of thyroid function and thyroid volume (TV). Moreover, calcitonin (CT), and its gene-related peptide have been demonstrated to play an important role in the implantation process. PURPOSE: To evaluate changes in TV and serum CT levels during pregnancy. METHODS: One hundred and fifty-five pregnant women were consecutively enrolled at the first trimester of gestation and underwent clinical, biochemical and sonographic assessment at enrollment, at the second and third trimesters and at 6 months after delivery. RESULTS: Throughout gestation serum TSH exceeded the upper specific first trimester cut-off in 5% of patients. TV significantly increased at the third trimester of gestation and returned to baseline levels at 6 months after delivery, while serum CT levels did not show significant changes. TV directly correlated with BMI or gestational weight gain at each trimester of pregnancy, while no significant association between serum CT levels and either weight or TV were found. Finally, in none of the patients with nodular goiter an increase in the volume of the nodules was noted. The appearance of a nodule was recorded during the second trimester in one patient. CONCLUSION: This study confirms a prevalence of thyroid autoimmunity/hypertropinemia in 3-5% of pregnant women and shows that serum CT does not change in relation to the transient increase in TV occurring during gestation. An adequate daily iodine supplementation might be particularly useful during pregnancy to limit the TSH increase and the resulting thyroid gland and nodule enlargement.

Rewiring of the apoptotic TGF-ß-SMAD/NFκB pathway through an oncogenic function of p27 in human papillary thyroid cancer.

Papillary thyroid carcinoma (PTC), the most frequent thyroid cancer, is characterized by low proliferation but no apoptosis, presenting frequent lymph-node metastasis. Papillary thyroid carcinoma overexpress transforming growth factor-beta (TGF-ß). In human cells, TGF-ß has two opposing actions: antitumoral through pro-apoptotic and cytostatic activities, and pro-tumoral promoting growth and metastasis. The switch converting TGF-ß from a tumor-suppressor to tumor-promoter has not been identified. In the current study, we have quantified a parallel upregulation of TGF-ß and nuclear p27, a CDK2 inhibitor, in samples from PTC. We established primary cultures from follicular epithelium in human homeostatic conditions (h7H medium). TGF-ß-dependent cytostasis occurred in normal and cancer cells through p15/CDKN2B induction. However, TGF-ß induced apoptosis in normal and benign but not in carcinoma cultures. In normal thyroid cells, TGF-ß/SMAD repressed the p27/CDKN1B gene, activating CDK2-dependent SMAD3 phosphorylation to induce p50 NFκB-dependent BAX upregulation and apoptosis. In thyroid cancer cells, oncogene activation prevented TGF-ß/SMAD-dependent p27 repression, and CDK2/SMAD3 phosphorylation, leading to p65 NFκB upregulation which repressed BAX, induced cyclin D1 and promoted TGF-ß-dependent growth. In PTC samples from patients, upregulation of TGF-ß, p27, p65 and cyclin D1 mRNA were significantly correlated, while the expression of the isoform BAX-ß, exclusively transcribed in apoptotic cells, was negatively correlated. Additionally, combined ERK and p65 NFκB inhibitors reduced p27 expression and potentiated apoptosis in thyroid cancer cells while not affecting survival in normal thyroid cells. Our results therefore suggest that the oncoprotein p27 reorganizes the effects of TGF-ß in thyroid cancer, explaining the slow proliferation but lack of apoptosis and metastatic behavior of PTC.

Recommendations for post-surgical thyroid ablation in differentiated thyroid cancer: a 2015 position statement of the Italian Society of Endocrinology.

UNLABELLED: Post-surgical ablation of thyroid remnant with radioactive iodine (RAI) in differentiated thyroid cancer (DTC) is aimed to destroy any thyroid remnant in the thyroid bed (remnant ablation) and any microscopic foci of cancer cells eventually present within the thyroid remnant (adjuvant therapy). The present text is an attempt to offer practice guidelines for the indication of thyroid ablation and the preparation of DTC patients considering the latest achievement in the field and the changing epidemiology of DTC observed in the last 10 years. METHODOLOGY: The executive committee of the Italian Society of Endocrinology appointed a task force of thyroid cancer expert including Nuclear Medicine Physicians and Endocrinologists to provide a consensus on the post-surgical ablation in thyroid cancer patients. The task force had no conflict of interest and had no commercial support. A number of specific topics were selected and the members selected relevant papers by searching in the Pubmed for articles published from 2000 to January 2015. Selected studies were categorized by level of evidence, and the recommendations were graded according to the level of evidence as high (A), moderate (B), or low (C).

Rare diseases in clinical endocrinology: a taxonomic classification system.

PURPOSE: Rare endocrine-metabolic diseases (REMD) represent an important area in the field of medicine and pharmacology. The rare diseases of interest to endocrinologists involve all fields of endocrinology, including rare diseases of the pituitary, thyroid and adrenal glands, paraganglia, ovary and testis, disorders of bone and mineral metabolism, energy and lipid metabolism, water metabolism, and syndromes with possible involvement of multiple endocrine glands, and neuroendocrine tumors. Taking advantage of the constitution of a study group on REMD within the Italian Society of Endocrinology, consisting of basic and clinical scientists, a document on the taxonomy of REMD has been produced. METHODS AND RESULTS: This document has been designed to include mainly REMD manifesting or persisting into adulthood. The taxonomy of REMD of the adult comprises a total of 166 main disorders, 338 including all variants and subtypes, described into 11 tables. CONCLUSIONS: This report provides a complete taxonomy to classify REMD of the adult. In the future, the creation of registries of rare endocrine diseases to collect data on cohorts of patients and the development of common and standardized diagnostic and therapeutic pathways for each rare endocrine disease is advisable. This will help planning and performing intervention studies in larger groups of patients to prove the efficacy, effectiveness, and safety of a specific treatment.

The clinical and molecular characterization of patients with dyshormonogenic congenital hypothyroidism reveals specific diagnostic clues for DUOX2 defects.

CONTEXT: Mutations in the DUOX2 gene have been associated with transient or permanent congenital hypothyroidism due to a dyshormonogenic defect. OBJECTIVE: This study aimed to verify the prevalence of DUOX2 mutations and the associated clinical features in children selected by criteria supporting a partial iodide organification defect (PIOD). PATIENTS AND METHODS: Thirty children with PIOD-like criteria were enrolled and genotyped. A detailed clinical characterization was undertaken together with the functional analysis of the DUOX2 variations and the revision of the clinical and molecular data of the literature. RESULTS: In this large selected series, the prevalence of the DUOX2 mutations was high (37%). We identified 12 missense variants, one splice site, and three frameshift DUOX2 mutations. Functional analyses showed significant impairment of H2O2 generation with five missense variants. Stop-codon mutants were shown to totally abolish DUOX2 activity by nonsense-mediated RNA decay, exon skipping, or protein truncation. DUOX2 mutations, either mono- or biallelic, were most frequently associated with permanent congenital hypothyroidism. Moreover, the present data suggested that, together with goiter and PIOD, the most significant features to select patients for the DUOX2 analysis are the low free T4 and the high TSH concentrations at the first postnatal serum sampling, despite borderline blood spot TSH. Interestingly, the analysis of previously described DUOX2 mutated cases confirmed the validity of these findings. CONCLUSIONS: The defects in the peroxide generation system are common among congenital hypothyroidism patients with PIOD. The most robust clinical parameters for selecting patients for DUOX2 analysis have been identified, and several DUOX2 variants have been functionally characterized.

Genetic defects of hydrogen peroxide generation in the thyroid gland.

Hydrogen peroxide (H2O2) is a key element in thyroid hormone biosynthesis. It is the substrate used by thyroid peroxidase for oxidation and incorporation of iodine into thyroglobulin, a process known as organification. The main enzymes composing the H2O2-generating system are the dual oxidase 2 (DUOX2) and the recently described DUOX maturation factor 2 (DUOXA2). Defects in these reactions lead to reduced thyroid hormone synthesis and hypothyroidism, with consequent increased TSH secretion and goiter. Since the first report in 2002 of DUOX2 mutations causing congenital hypothryoidism (CH), to date 25 different mutations have been described. Affected patients show a positive perchlorate discharge test and high phenotypic variability, ranging from transient to permanent forms of CH. Up to now, only two cases of CH due to DUOXA2 defects have been published. They also suggest the existence of a great genotype-phenotype variability. The phenotypic expression is probably influenced by genetic background and environmental factors. DUOX and DUOXA constitute a redundant system in which DUOX1/DUOXA1 can at least partially replace the function of DUOX2/DUOXA2. Furthermore, increased nutritional iodide could ensure a better use of H2O2 provided by DUOX1.

The widened use of exogenous stimulation with recombinant human TSH to treat metastatic thyroid carcinoma in Italy.

Recently, in Italy, the reimbursement for the use of rhTSH in preparing patients for radiometabolic treatment of iodine-avid metastases from differentiated thyroid cancer has been made possible. Intramuscular administration of rhTSH increases the radioiodine uptake and thyroglobulin production by thyroid cells. In addition to the previous indications on the use of rhTSH (mainly: serum thyreoglobulin assay with or without 131I scintigraphy and ablation with 131I of remnants in low risk patients), the reimbursement is now allowed for the treatment with radioiodine of iodine-avid loco-regional and distant metastases, in subjects with inability to reach adequate TSH levels and/or severe clinical conditions which could be potentially worsened by other concurrent diseases (history of stroke or transient ischemic attack, severe cardiac disease, renal failure or major psychiatric disorders). The Italian Medicines Agency (AIFA) approved this use (and added this hormone in the special list of drugs regulated by the D.Lgs 648/96) on the basis of a series of scientific evidences, proposed by a "team of experts". In the present paper we illustrate the scientific background of the use of rhTSH (clinical usefulness, economic considerations, aspects related to a better quality of life) that allowed the modification of the reimbursement and how it was made possible in the Italian legislative context.

[Radiometabolic therapy for metastatic thyroid carcinoma: overview of the literature and rational bases for the use of recombinant human TSH]. / La terapia radiometabolica del carcinoma della tiroide metastatico: overview della letteratura e basi razionali all'utilizzo del TSH umano ricombinante.

The established treatment for differentiated thyroid carcinoma (DTC) is founded on total thyroidectomy and subsequent administration of radioiodine (131I) to ablate the thyroid remnant and to treat the metastatic disease. In the case of metastatic or recurrent disease, further cycles of 131I therapy are often necessary. The condition for maximizing the effectiveness of the treatment is to have an adequate stimulation from TSH, which must be >25-30 mIU/L. This elevation is achieved either discontinuing the hormone suppression therapy for an appropriate period, or administering recombinant human TSH (rhTSH). The latter has shown good clinical efficacy in patients with residual thyroid gland and is nowadays commonly employed since it is easy to use and allows to avoid the side effects of hypothyroidism. It thus represents a good alternative to thyroid hormone withdrawal for the remnant ablation, while is still open the question if its efficacy on the management of metastatic disease is superimposable to thyroid hormone withdrawal. To this purpose, a Panel of expert reviewed the literature, assessing the advantages and disadvantages for the patient, as well as the impact in terms of cost and benefit to the National Health Service. The work of the Panel concluded with a proposal for the use of rhTSH in selected patients with metastatic DTC, in which is considered the efficacy and safety of the product and is examined its use in terms of costs; this proposal was accepted by the Italian Drug Agency resulting in an update of the indications for rhTSH.

Increased risk for non-autoimmune hypothyroidism in young patients with congenital heart defects.

CONTEXT: Newborns with congenital hypothyroidism (CH) have an increased risk for congenital heart defects (CHD) due to a common embryonic developmental program between thyroid gland and heart and great vessels. OBJECTIVE: Our objective was to investigate the prevalence and origin of thyroid disorders in young patients with CHD. DESIGN AND SETTING: We conducted a prospective observational study between January 2007 and January 2009 in academic Pediatric Cardiosurgery and Endocrinology. PATIENTS: Patients included 324 children (164 males, 160 females, aged 0.2-15.4 yrs) with CHD. INTERVENTION: Subjects underwent hormonal and genetic screening. MAIN OUTCOME MEASURES: Serum TSH and thyroid hormone levels were assessed. RESULTS: Two CHD patients were diagnosed with CH at the neonatal screening (1:162). Mild hypothyroidism (serum TSH > 4.0 µU/ml) was diagnosed and confirmed 6 months later [TSH = 5.4 ± 1.5 µU/ml; free T(4) = 1.3 ± 0.2 ng/dl (normal values 0.8-1.9)] in 37 children (11.5%) who were negative at neonatal screening. Hypothyroidism was not related to type of CHD, whereas TSH levels positively correlated with serum N-terminal pro-type B natriuretic peptide levels. Biochemical and ultrasound findings consistent with thyroid autoimmunity were present in three of 37 hypothyroid children (8.1%). One patient had hemiagenesis (2.7%). Variations in candidate genes were screened in CHD patients. NKX2.5 coding sequence was normal in all samples. A 3-Mb microdeletion in 22q11.2 was detected in three patients (8.3%), whereas only known polymorphisms were identified in TBX1 coding sequence. CONCLUSIONS: CHD patients have an increased risk for both CH (10-fold higher) and acquired mild hypothyroidism (3-fold higher). Unrecognized mild hypothyroidism may negatively affect the outcome of CHD children, suggesting that thyroid function should be repeatedly checked. Thyroid autoimmunity and 22q11.2 microdeletions account for small percentages of these cases, and still unknown mechanisms underline such a strong association.

DUOXS defects: Genotype-phenotype correlations.

Congenital hypothyroidism (CH) is the most common congenital endocrine disorder, accounting for up to 1:1500 newborns per year. CH can be related to defects in either formation and migration of the thyroid gland (dysgenesis) or thyroid hormone synthesis. The pathogenesis of dysgenetic CH is still largely unknown. On the contrary, several mutations have been found in different genes involved in thyroid dyshormonogenesis (such as pendrin, thyroperoxidase-TPO, thyroglobulin). Recently, new genes involved in the etiology of dyshormonogenesis have been identified: dual oxidase 2 (DUOX2) and dual oxidase maturation factor 2 (DUOXA2). They are the principal elements generating the hydrogen peroxide needed for TPO function. Mutations in these genes have been associated to transient or permanent CH, with a high intra and interfamilial phenotypic variability. Some hypotheses have been drawn to explain the variability of the DUOX2/A2 phenotype. Among them, the existence of other H(2)0(2) generating systems, the different requirements for thyroid hormones according to age, the ethnicity, the intake of iodine. In the present paper, the genetic and clinical features of CH caused by defects in the peroxide generator system will be revised.

Absence of primary hypothyroidism and goiter in Slc26a4 (-/-) mice fed on a low iodine diet.

BACKGROUND: Mutations in the SLC26A4 gene, coding for the anion transporter pendrin, are responsible for Pendred syndrome, characterized by congenital sensorineural deafness and dyshormonogenic goiter. The physiological role of pendrin in the thyroid is still unclear and the lack of a thyroid phenotype in some patients with SLC26A4 mutations and in Slc26a4 (-/-) mice indicate the existence of environmental or individual modifiers able to compensate for pendrin inactivation in the thyroid. Since pendrin can transport iodide in vitro, variations in iodide supply have been claimed to account for the thyroid phenotype associated with pendrin defects. AIM: The Slc26a4 (-/-) mouse model was used to test the hypothesis that iodide supply may influence the penetrance and expressivity of SLC26A4 mutations. MATERIALS AND METHODS: Slc26a4 (-/-) and (+/+) mice were fed up to 6 months on a standard or low iodine diet and were evaluated for thyroid structural abnormalities or biochemical hypothyroidism. RESULTS: A 27-fold iodide restriction induced similar modifications in thyroid histology, but no differences in thyroid size, T4 or TSH levels were observed between between Slc26a4 (-/-) and (+/+) mice, either in standard conditions and during iodine restriction. CONCLUSIONS: Iodide restriction is not able to induce a thyroid phenotype in Slc26a4 (-/-) mice. These experimental data, together with those coming from a review of familial Pendred cases leaving in regions either with low or sufficient iodide supply, support the idea that the expression of thyroid phenotype in Pendred syndrome is more powerfully influenced by individual factors than by dietary iodide.

PKC-epsilon-dependent cytosol-to-membrane translocation of pendrin in rat thyroid PC Cl3 cells.

We studied the expression and the hormonal regulation of the PDS gene product, pendrin, which is, in thyrocytes, responsible for the iodide transport out of the cell. We show that PC Cl3 cells, a fully differentiated thyroid cell line, grown without TSH and insulin, express very low level of PDS mRNA; such expression is greatly increased after stimulation with insulin or TSH. (125)I pre-loaded cells showed an (125)I efflux accelerated in chloride-containing buffer with respect to chloride-free buffer, suggesting that this efflux is chloride dependent. By immunoblotting, pendrin was found in agonists-stimulated cells, whereas it was barely detectable in un-stimulated cells. An increase in both PDS mRNA and protein was also obtained using phorbol ester PMA, or using 8-Br-cAMP and forskolin. Stimulation with insulin (1 microg/ml; 0-40 min) provoked the cytosol-to-membrane translocation of pendrin and a decrease of intracellular I(-) content in (125)I pre-loaded cells. Insulin- or PMA-treated cells also showed a cytosol-to-membrane translocation of PKC-delta and -epsilon. Inhibition of both PKC-delta and -epsilon activities by GF109203X blocked pendrin translocation, whilst the inhibition of PKA did not. The selective inhibition of PKC-delta by rottlerin did not affect the insulin-provoked translocation of pendrin whilst it was inhibited by a PKC-epsilon translocation inhibitor peptide and also by PKC-epsilon downregulation using the small interfering RNA, thus indicating that such translocation was due to PKC-epsilon activity. In conclusion, our study demonstrates that, in PC Cl3 cells, pendrin expression and localisation are regulated by insulin and influenced by a PKC-epsilon-dependent intracellular pathway.

Expanding use of recombinant hTSH.

The clinical benefits of recombinant human thyroid-stimulating hormone (rhTSH; Thyrogen, Genzyme Corp., Cambridge, MA, USA) are well established as an alternative stimulation procedure to thyroid hormone withdrawal in the follow-up of thyroid cancer patients. rhTSH has the advantage to avoid both hypothyroidism, with a major impact on the quality of life, and the side effects on tumor growth related to the long-lasting TSH increase. More recently, alternative uses have been proposed, including treatment of nodular goiter, TSH stimulation to enhance PET scanning and chemotherapy treatment, and differential diagnosis of congenital hypothyroidism. In benign thyroid diseases, rhTSH administration increases thyroid uptake resulting in a more homogeneous distribution of the tracer, and allows to reduce the dose of 131I maintaining the same effects on thyroid shrinkage. Moreover, rTSH stimulation improves the detectability of occult thyroid metastases with FDG-PET, and promising results have been obtained in the response rate of poorly differentiated thyroid cancer submitted to chemotherapy after rhTSH stimulation. Finally, rhTSH testing has been proved to be safe and to lead, in association with ultrasound, to the differential diagnosis of congenital hypothyroidism during L-thyroxine, allowing the appropriate clinical/genetic management of the disease and thus representing a valuable alternative to L-thyroxine withdrawal.

Correlation between B-RAFV600E mutation and clinico-pathologic parameters in papillary thyroid carcinoma: data from a multicentric Italian study and review of the literature.

Recently, a somatic point mutation of the B-RAF gene (V600E) has been identified as the most common genetic event in papillary thyroid carcinoma (PTC), with a prevalence variable among different series. Since discordant data on the clinico-pathologic features of B-RAF mutated PTC are present in the literature, the aim of the present co-operative study was to establish the prevalence of this genetic alteration and to perform a genotype-phenotype correlation in a large cohort of patients with PTC. To this purpose, a series of 260 sporadic PTCs with different histological variants were included in the study. The mutational analysis of the B-RAF gene was performed either by RT-PCR followed by single-stranded conformational polymorphism or by PCR and direct sequencing. Statistical analyses were obtained by means of chi2/Fisher's exact test and t-test. Overall, a heterozygous T > A transversion at nucleotide 1799 (V600E) was found in 99 out of 260 PTCs (38%). According to the histological type of the tumor, the B-RAF (V600E) mutation was present in 48.3% of cases of classic PTCs (85 out of 176), in 17.6% (nine out of 51) of follicular variants of PTCs, in 21.7% (five out of 23) in other PTC variants and in none of the ten poorly differentiated tumors. B-RAF (V600E) was significantly associated with the classic variant of PTC (P = 0.0001) and with an older age at diagnosis (P = 0.01). No statistically significant correlation was found among the presence of B-RAF (V600E) and gender, tumor node metastasis (TNM), multicentricity of the tumor, stage at diagnosis and outcome. In conclusion, the present study reports the prevalence of B-RAF (V600E) (38%) in the largest series of sporadic PTCs, including 260 cases from three different Italian referring centers. This prevalence is similar to that calculated by pooling together all data previously reported, 39.6% (759 out of 1914 cases), thus indicating that the prevalence of this genetic event lies around 38-40%. Furthermore, B-RAF (V600E) was confirmed to be associated with the papillary growth pattern, but not with poorer differentiated PTC variants. A significant association of B-RAF mutation was also found with an older age at diagnosis, the mutation being very rare in childhood and adolescent PTCs. Finally, no correlation was found with a poorer prognosis and a worse outcome after a median follow-up of 72 months.

Medullary and papillary carcinoma of the thyroid gland occurring as a collision tumour: report of three cases with molecular analysis and review of the literature.

We report the simultaneous occurrence of medullary thyroid carcinoma (MTC) and papillary thyroid carcinoma (PTC), presenting as spatially distinct and well-defined tumour components, in three cases. In the first patient, histology, immunohistochemistry and electron microscopy demonstrated an MTC in the one nodule and PTC in two additional lesions. Non-neoplastic thyroid parenchyma separated the three nodules. Metastasis from PTC was diagnosed in a regional lymph node. Genetic analysis of both tumour components showed a distinctive mutational pattern: in the MTC a Cys634Arg substitution in exon 11 of the RET gene and in the two PTC foci a Val600Glu substitution in exon 15 of the BRAF gene. The other two patients are members of a large multigenerational family affected with familial MTC due to a germline mutation of the RET gene (Ala891Ser). Both patients harboured, besides medullary cancer and C-cell hyperplasia, distinct foci of papillary thyroid cancer, which was positive for Val600Glu BRAF mutation. Review of the literature disclosed 18 similar lesions reported and allowed the identification of different patterns of clinical presentation and biological behaviour. So far, the pathogenesis of these peculiar cases of thyroid malignancy has been completely unknown, but an underlying common genetic drive has been hypothesised. This is the first report in which two mutations, in the RET and BRAF genes, have been identified in three cases of MTC/PTC collision tumour, thus documenting the different genetic origin of these two coexisting carcinomas.

Monoallelic expression of mutant thyroid peroxidase allele causing total iodide organification defect.

Mutations in the thyroid peroxidase (TPO) gene lead to severe congenital hypothyroidism due to total iodide organification defect (TIOD). According to the recessive mode of inheritance, patients are homozygous or compound heterozygous for gene mutations. However, about 17% of cases with typical phenotype harbor a single TPO-mutated allele. We present a TIOD family in which the three affected siblings had a single genomic TPO mutation (R693W) inherited from the unaffected father. Other mutations were not found, although all TPO coding exons and exon/intron boundaries were sequenced. Eleven different polymorphisms were found in hetero- or homozygosity in all family members. On the contrary, using retrotranscribed thyroid tissue RNA, all heterozygous polymorphisms and the mutation were homozygous. The distribution of the polymorphisms indicated that only the mutant paternal allele is transcribed at the thyroid tissue level. We excluded the presence of major deletions involving the maternal chromosome at 2p25 and of maternal imprinting or mutations in part of the regulatory regions of the gene. In summary, we report one family with TIOD due to monoallelic expression of a mutant TPO allele in the thyroid. This mechanism might be generally involved in TIOD cases with a single TPO-mutated allele.