RESUMO
BACKGROUND: Aim of the present study was to evaluate the clinical impact of fluorine-18F-fluorodeoxyglucose PET/CT (18F-FDG-PET/CT) concurrent with post-therapeutic whole-body radioiodine scan (TxWBS) after first radioiodine (RAI) treatment in patients with high-risk differentiated thyroid carcinoma (DTC). METHODS: This was a retrospective, single-center study including 39 patients with DTC (22 females, 17 males, median age 54; IQR: 35-60 years, 87% papillary thyroid cancer, 13% follicular thyroid cancer). All patients underwent 18F-FDG-PET/CT and RAI treatment, both performed off L-T4 about 3 months after total thyroidectomy. TxWBS was obtained 3 days afterwards using planar technique and SPECT/CT of neck and thorax regions. Semiquantitative analysis was performed on positive 18F-FDG-PET/CT scans to assess SUV
Assuntos
Tireoglobulina , Neoplasias da Glândula Tireoide , Masculino , Feminino , Humanos , Pessoa de Meia-Idade , Fluordesoxiglucose F18 , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada , Radioisótopos do Iodo/uso terapêutico , Estudos Retrospectivos , Neoplasias da Glândula Tireoide/diagnóstico por imagem , Neoplasias da Glândula Tireoide/radioterapia , Neoplasias da Glândula Tireoide/cirurgiaRESUMO
This study investigated the peripheral blood lymphocytes (PBL) response to a dose of γ-rays in patients treated with radioiodine (I-131) for hyperthyroidism vs. healthy controls, to gain information about the individual lymphocytes' radio-sensitivity. Blood samples were taken from 18 patients and 10 healthy donors. Phosphorylated histone variant H2AX (γ-H2AX) and micronuclei (MN) induction were used to determine the change in PBL radio-sensitivity and the correlations between the two types of damage. The two assays showed large inter-individual variability in PBL background damage and in radio-sensitivity (patients vs. healthy donors). In particular, they showed an increased radio-sensitivity in 36% and 33% of patients, decrease in 36% and 44%, respectively. There was a scarce correlation between the two assays and no dependence on age or gender. A significant association was found between high radio-sensitivity conditions and induced hypothyroidism. PBL radio-sensitivity in the patient group was not significantly affected by treatment with I-131, whereas there were significant changes inter-individually. The association found between clinical response and PBL radio-sensitivity suggests that the latter could be used in view of the development of personalized treatments.
Assuntos
Hipertireoidismo , Radioisótopos do Iodo , Relação Dose-Resposta à Radiação , Humanos , Hipertireoidismo/radioterapia , Radioisótopos do Iodo/uso terapêutico , Linfócitos , Testes para Micronúcleos , Tolerância a RadiaçãoRESUMO
Nuclear medicine plays an increasingly important role in several neoplasms management through a theragnostic approach by which targeted molecular imaging and radiotherapy are obtained with the use of radionuclide pairs with similar characteristics. In some cases, nuclear theragnostic use a pair of agents with identical chemical and biological characteristics while in others are employed theragnostic molecules which are not chemically or biologically identical but show similar biodistribution (so-called "twins in spirit" radiopharmaceuticals). This strategy was developed for the first time over 75 years ago, when iodine-131 was used for diagnostic imaging, confirmation of target expression and radionuclide therapy of thyroid cancer. Other theragnostic approaches were subsequently introduced with significant clinical results and some of them are currently considered standard treatment for different cancers. However, as any other therapy, also nuclear theragnostic treatment carries the potential risk of early deterministic and late stochastic off-target adverse effects, generally minimal and easily managed. This article reviews the reported side effects and risks of the main radiopharmaceuticals used for nuclear theragnostic in oncology for the treatment of thyroid cancer, neuroendocrine neoplasms, adrenergic tumors, metastatic prostate cancer, and liver tumors. Selecting appropriate patients using a multidisciplinary approach, meticulous pretreatment planning and knowledge of methods permit to decrease the incidence of these potential side effects.
Assuntos
Medicina Nuclear , Neoplasias da Próstata , Humanos , Radioisótopos do Iodo , Masculino , Compostos Radiofarmacêuticos , Distribuição TecidualRESUMO
Hybrid imaging procedures such as single-photon emission computed tomography/computed tomography (SPECT/CT) and positron emission tomography/computed tomography (PET/CT) showed a rapid diffusion in recent years because of their high sensitivity, specificity, and accuracy, due to a more accurate localization and definition of scintigraphic findings. However, hybrid systems inevitably lead to an increase in patient radiation exposure because of the added CT component. Effective doses due to the radiopharmaceuticals can be estimated by multiplying the administered activities by the effective dose coefficients, while for the CT component the dose-length product can be multiplied by a conversion coefficient k. However, the effective dose value is subject to a high degree of uncertainty and must be interpreted as a broad, generic estimate of biologic risk. Although the effective dose can be used to estimate and compare the risk of radiation exposure across multiple imaging techniques, clinicians should be aware that it represents a generic evaluation of the risk derived from a given procedure to a generic model of the human body. It cannot be applied to a single individual and should not be used for epidemiologic studies or the estimation of population risks due to the inherent uncertainties and oversimplifications involved. Practical ways to reduce radiation dose to patients eligible for hybrid imaging involve adjustments to both the planning phase and throughout the execution of the study. These methods include individual justification of radiation exposure, radiopharmaceutical choice, adherence to diagnostic reference levels (DLR), patient hydration and bladder voiding, adoption of new technical devices (sensitive detectors or collimators) with new reconstruction algorithms, and implementation of appropriate CT protocols and exposure parameters.
Assuntos
Imagem Multimodal/efeitos adversos , Medicina Nuclear , Doses de Radiação , Exposição à Radiação/prevenção & controle , Compostos Radiofarmacêuticos/efeitos adversos , Humanos , Imagem Multimodal/métodos , Imagem Multimodal/estatística & dados numéricos , Imagem Multimodal/tendências , Medicina Nuclear/estatística & dados numéricos , Medicina Nuclear/tendências , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada/efeitos adversos , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada/estatística & dados numéricos , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada/tendências , Editoração/estatística & dados numéricos , Editoração/tendências , Compostos Radiofarmacêuticos/administração & dosagem , Risco , Sensibilidade e Especificidade , Tomografia Computadorizada com Tomografia Computadorizada de Emissão de Fóton Único/efeitos adversos , Tomografia Computadorizada com Tomografia Computadorizada de Emissão de Fóton Único/estatística & dados numéricos , Tomografia Computadorizada com Tomografia Computadorizada de Emissão de Fóton Único/tendências , Tomografia Computadorizada por Raios X/efeitos adversosRESUMO
Positron emission tomography (PET) and PET/computed tomography (PET/CT) with different tracers have been increasingly used in patients with thyroid tumours. The aim of this article is to perform an overview based on literature data about the usefulness of PET imaging in this setting. The role of Fluorine-18-Fluorodeoxyglucose (FDG) PET and PET/CT in differentiated thyroid carcinoma (DTC) is well established, particularly in patients presenting with elevated serum thyroglobulin levels and negative radioiodine whole-body scan. Iodine-124 PET and PET/CT may serve a role in staging DTC and obtaining lesional dosimetry for a better and more rationale planning of treatment with Iodine-131. FDG-PET and PET/CT are useful in the post-thyroidectomy staging of high-risk patients with less differentiated histological subtypes. PET and PET/CT with different tracers seem to be useful methods in localizing the source of elevated calcitonin levels in patients with recurrent medullary thyroid carcinoma. Incorporation of FDG-PET or PET/CT into the initial workup of patients with indeterminate thyroid nodules at fine needle aspiration biopsy deserves further investigation. FDG-PET report should suggest further evaluation when focal thyroid incidentalomas are described because these findings are associated with a significant risk of cancer.
Assuntos
Imagem Multimodal , Tomografia por Emissão de Pósitrons , Neoplasias da Glândula Tireoide/diagnóstico por imagem , Tomografia Computadorizada por Raios X , Biomarcadores Tumorais/sangue , Biópsia por Agulha Fina , Fluordesoxiglucose F18 , Humanos , Estadiamento de Neoplasias , Compostos Radiofarmacêuticos , Neoplasias da Glândula Tireoide/patologia , Neoplasias da Glândula Tireoide/terapia , Tireoidectomia , Imagem Corporal TotalRESUMO
AIM: This guideline (GL) is aimed at providing a reference for the management of non-functioning, benign thyroid nodules causing local symptoms in adults outside of pregnancy. METHODS: This GL has been developed following the methods described in the Manual of the National Guideline System. For each question, the panel appointed by Associazione Medici Endocrinology (AME) identified potentially relevant outcomes, which were then rated for their impact on therapeutic choices. Only outcomes classified as "critical" and "important" were considered in the systematic review of evidence and only those classified as "critical" were considered in the formulation of recommendations. RESULTS: The present GL contains recommendations about the respective roles of surgery and minimally invasive treatments for the management of benign symptomatic thyroid nodules. We suggest hemithyroidectomy plus isthmectomy as the first-choice surgical treatment, provided that clinically significant disease is not present in the contralateral thyroid lobe. Total thyroidectomy should be considered for patients with clinically significant disease in the contralateral thyroid lobe. We suggest considering thermo-ablation as an alternative option to surgery for patients with a symptomatic, solid, benign, single, or dominant thyroid nodule. These recommendations apply to outpatients, either in primary care or when referred to specialists. CONCLUSION: The present GL is directed to endocrinologists, surgeons, and interventional radiologists working in hospitals, in territorial services, or private practice, general practitioners, and patients. The available data suggest that the implementation of this GL recommendations will result in the progressive reduction of surgical procedures for benign thyroid nodular disease, with a decreased number of admissions to surgical departments for non-malignant conditions and more rapid access to patients with thyroid cancer. Importantly, a reduction of indirect costs due to long-term replacement therapy and the management of surgical complications may also be speculated.
Assuntos
Neoplasias da Glândula Tireoide , Nódulo da Glândula Tireoide , Adulto , Humanos , Itália/epidemiologia , Neoplasias da Glândula Tireoide/patologia , Nódulo da Glândula Tireoide/diagnóstico , Nódulo da Glândula Tireoide/cirurgia , Tireoidectomia , Resultado do TratamentoRESUMO
BACKGROUND: Although papillary thyroid microcarcinoma (PTMC) is diagnosed with increasing frequency, the best therapeutic option and follow-up protocol have not been established yet, especially in the case of incidental diagnosis. We reviewed our series of patients with PTMC to determine risk factors for recurrence in an area where there is a high prevalence of goiter. METHODS: The medical records of all patients who underwent thyroidectomy with a final pathology report of PTMC between October 2002 and June 2007 were reviewed. PTMC was defined as a papillary thyroid carcinoma 10 mm or less in diameter. Follow-up evaluation was obtained by outpatient consultation and/or telephone interview. RESULTS: In a series of 2,220 patients who underwent thyroidectomy for a thyroid carcinoma, 933 had a PTMC. Diagnosis was incidental in 704 patients (75.5%). Upon multivariate analysis, tumor size, nonincidental diagnosis, and neck node metastases at diagnosis were independent risk factors for extracapsular spread (ECS), while ECS, multifocal disease, and number of removed lymph nodes were independent risk factors for lymph node metastases at diagnosis. Follow-up evaluation was completed in 287 patients, 9 (3.1%) of whom experienced recurrence. The number of removed and metastasized nodes at first operation and the length of the follow-up were independent risk factors for recurrent disease. CONCLUSIONS: Incidental diagnosis of PTMC is frequent in a high prevalence of goiter area. PTMC shows a variable degree of aggressiveness. Management protocols should be based on patient- and tumor-related prognostic factors, as for larger tumors.
Assuntos
Carcinoma Papilar/patologia , Neoplasias da Glândula Tireoide/patologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Carcinoma Papilar/epidemiologia , Carcinoma Papilar/cirurgia , Distribuição de Qui-Quadrado , Criança , Feminino , Bócio/epidemiologia , Humanos , Itália/epidemiologia , Modelos Lineares , Excisão de Linfonodo , Metástase Linfática , Masculino , Pessoa de Meia-Idade , Invasividade Neoplásica , Recidiva Local de Neoplasia , Prevalência , Prognóstico , Fatores de Risco , Neoplasias da Glândula Tireoide/epidemiologia , Neoplasias da Glândula Tireoide/cirurgia , TireoidectomiaRESUMO
Struma ovarii is a rare monodermal ovarian teratoma composed predominantly of mature thyroid tissue. We describe herein the case of a 22-year-old woman who underwent a right salpingo-oophorectomy for struma ovarii at the age of 12 years, who was admitted 8 years later with signs and symptoms of a left pelvic tumor. Laparoscopy detected a left ovarian endometriotic cyst and multiple nodules on the pelvic peritoneum, right lateral abdominal wall, diaphragm, vesical plica and liver. The diagnosis was abdominal and pelvic widespread dissemination of recurrent struma ovarii, with features consistent with the follicular variant of papillary thyroid carcinoma. The patient was treated with a combination of conservative surgery and two 131I administrations (cumulative activity of 350 mCi after dosimetric evaluation). Because of the high degree of hormonogenesis shown by the metastases, the first administration was performed following use of recombinant human (rh) thyroid-stimulating hormone (TSH) to reach adequate TSH levels. To avoid the 'stunning effect' and to obtain high-quality scintigraphy, a whole-body scan was performed with 123I after rh-TSH and before the 131I therapy. We also discuss the potential role and the possible benefit of using gonadotropin-releasing hormone analogs and ovarian tissue cryopreservation to preserve fertility in women treated with 131I for pelvic metastases from malignant struma ovarii.
Assuntos
Radioisótopos do Iodo/uso terapêutico , Recidiva Local de Neoplasia/radioterapia , Recidiva Local de Neoplasia/cirurgia , Neoplasias Ovarianas/radioterapia , Neoplasias Ovarianas/cirurgia , Estruma Ovariano/radioterapia , Estruma Ovariano/cirurgia , Adulto , Feminino , Fertilidade , Humanos , Metástase Neoplásica , Cintilografia , Tireotropina/uso terapêuticoRESUMO
A 72-year-old man underwent total thyroidectomy and radioiodine remnant ablation for papillary thyroid cancer in 2016. The posttherapy whole-body scan showed uptake in the neck, classified as residual thyroid tissue. Two years later, the patient came to our observation to perform a second radioiodine therapy for high levels of thyroglobulin. The planar posttherapy scan showed a focal radioiodine area in the neck. SPECT/CT diagnosed a voluminous esophageal diverticulum located in the upper third of the esophagus. A CT performed to discover the source of thyroglobulin excluded locoregional or distant metastases and confirmed the presence of a Zenker diverticulum.
Assuntos
Divertículo Esofágico/diagnóstico por imagem , Divertículo Esofágico/metabolismo , Radioisótopos do Iodo/metabolismo , Tomografia Computadorizada com Tomografia Computadorizada de Emissão de Fóton Único , Idoso , Transporte Biológico , Carcinoma Papilar/radioterapia , Carcinoma Papilar/cirurgia , Humanos , Masculino , Câncer Papilífero da Tireoide , Neoplasias da Glândula Tireoide/radioterapia , Neoplasias da Glândula Tireoide/cirurgia , Tireoidectomia , Imagem Corporal TotalRESUMO
The classical therapeutic approach to patients with differentiated thyroid cancer (DTC) is based on total or near-total thyroidectomy, followed by (131)I treatment and thyroid-stimulating hormone suppressive therapy. This approach allows complete cure in many patients, especially when the tumour is diagnosed at an early stage; it also allows long-term survival in patients with locoregional recurrences or distant metastases if they can be treated with (131)I. In contrast, when metastatic DTC deposits lose their ability to trap (131)I (non-functioning metastases), a worse prognosis is expected. Nevertheless, in patients with locoregional non-functioning recurrences, an early diagnosis and prompt surgical extirpation can lead to a favourable prognosis. In these cases, radical surgery is needed. This can be achieved with radio-guided surgery using a hand-held gamma probe and a tumour-seeking radiotracer to detect, intraoperatively, the smallest metastatic lesions. In this paper, we discuss the two principal techniques proposed in the literature for radio-guided surgery of non-functioning DTC metastatic recurrences, the first using high doses of (131)I and the second using low doses of 99mTc-Sestamibi.
Assuntos
Radioisótopos do Iodo , Recidiva Local de Neoplasia/diagnóstico por imagem , Recidiva Local de Neoplasia/prevenção & controle , Tecnécio Tc 99m Sestamibi , Neoplasias da Glândula Tireoide/diagnóstico por imagem , Neoplasias da Glândula Tireoide/cirurgia , Tireoidectomia , Ensaios Clínicos como Assunto , Humanos , Prognóstico , Cintilografia , Compostos Radiofarmacêuticos , Neoplasias da Glândula Tireoide/radioterapia , Resultado do TratamentoRESUMO
UNLABELLED: BACKGROUND/MATERIAL AND METHODS: The aim of this study was to assess the reliability of radioiodine ((131)I) and a gamma probe for radio-guided surgery (RGS) to detect and radically dissect lymph node recurrence (LNR) in 15 patients with differentiated thyroid cancer (DTC). The major inclusion criterion was the presence of a radioiodine-positive LNR after previous total thyroidectomy and at least two ineffective (131)I treatments. The protocol was designed as follows: Day 0--all patients were hospitalized and received 3.7 GBq of (131) I while clinically hypothyroid. Day 3--pre-surgery whole-body scan with a therapeutic (131)I dose (TxWBS) was acquired. Day 5--neck surgery using a gamma probe (Navigator GPS, AutoSuture, Italy), recording the absolute counts and the lesion/background (L/B) counts ratio was performed. Day 7--post-surgery TxWBS was performed using the remaining radioactivity. RESULTS AND CONCLUSIONS: This protocol permitted us to identify neoplastic foci with high sensitivity and specificity, enabling us to remove lymph node metastases resistant to radioiodine therapy in a single session. The protocol also allowed detection of some additional tumoural foci in sclerotic areas or behind vascular structures that were not seen at the pre-surgery TxWBS evaluation.
Assuntos
Radioisótopos do Iodo , Recidiva Local de Neoplasia/diagnóstico por imagem , Recidiva Local de Neoplasia/cirurgia , Cirurgia Assistida por Computador/métodos , Neoplasias da Glândula Tireoide/diagnóstico por imagem , Neoplasias da Glândula Tireoide/cirurgia , Adulto , Idoso , Feminino , Humanos , Radioisótopos do Iodo/uso terapêutico , Metástase Linfática , Masculino , Pessoa de Meia-Idade , Recidiva Local de Neoplasia/radioterapia , Prognóstico , Cintilografia , Compostos Radiofarmacêuticos/uso terapêutico , Neoplasias da Glândula Tireoide/radioterapia , Tireoidectomia/métodos , Resultado do TratamentoAssuntos
Exposição Ambiental/efeitos adversos , Medicina Nuclear , Proteção Radiológica/métodos , Cuidadores , Família , Humanos , Corpo Clínico , Tomografia por Emissão de Pósitrons/efeitos adversos , Protetores contra Radiação/farmacologia , Radiometria , Risco , Tomografia Computadorizada por Raios X/efeitos adversosAssuntos
Adenocarcinoma Folicular/radioterapia , Carcinoma Papilar/radioterapia , Radioisótopos do Iodo/uso terapêutico , Radiometria/métodos , Compostos Radiofarmacêuticos/uso terapêutico , Doenças da Glândula Tireoide/radioterapia , Neoplasias da Glândula Tireoide/radioterapia , Adenocarcinoma Folicular/diagnóstico por imagem , Carcinoma Papilar/diagnóstico por imagem , Relação Dose-Resposta à Radiação , Humanos , Hipertireoidismo/radioterapia , Radioisótopos do Iodo/administração & dosagem , Radioisótopos do Iodo/farmacocinética , Tomografia por Emissão de Pósitrons , Compostos Radiofarmacêuticos/administração & dosagem , Compostos Radiofarmacêuticos/farmacocinética , Dosagem Radioterapêutica , Proteínas Recombinantes/farmacologia , Proteínas Recombinantes/uso terapêutico , Doenças da Glândula Tireoide/diagnóstico por imagem , Neoplasias da Glândula Tireoide/diagnóstico por imagem , Tireotropina/farmacologia , Tireotropina/uso terapêuticoRESUMO
A case is presented of a posterior mediastinal mass arising in a 57-year-old woman with severe compressive cervical symptoms and hyperthyroidism. Computed tomography showed intrathoracic thyroid tissue that displaced the trachea towards the front and the right and invaded the posterior mediastinum. Pathological examination showed features of a poorly differentiated (insular) thyroid carcinoma. To the best of our knowledge, this is the first reported case of a posterior mediastinal insular thyroid carcinoma with thyroid hyperfunction.
Assuntos
Carcinoma , Hipertireoidismo/etiologia , Neoplasias do Mediastino , Neoplasias da Glândula Tireoide , Carcinoma/complicações , Carcinoma/diagnóstico , Carcinoma/cirurgia , Diagnóstico Diferencial , Feminino , Bócio Nodular/complicações , Humanos , Neoplasias do Mediastino/complicações , Neoplasias do Mediastino/diagnóstico , Neoplasias do Mediastino/cirurgia , Pessoa de Meia-Idade , Neoplasias da Glândula Tireoide/complicações , Neoplasias da Glândula Tireoide/diagnóstico , Neoplasias da Glândula Tireoide/cirurgiaRESUMO
In recent years, 2-[(18)F]-fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography (FDG-PET/CT) has emerged as an important tool for the postoperative management of patients with differentiated thyroid cancer (DTC) and it is widely used in selected clinical situations. The most valuable role that FDG-PET/CT plays in clinical practice is that it can be used to obtain prognostic information in patients with increasing thyroglobulin (Tg) levels and negative (131)I whole-body scan post-thyroidectomy and radioiodine (RAI) ablation. FDG-PET/CT may also have a potential role in the initial staging and follow-up of high-risk patients with aggressive histological subtypes, in the identification of patients who are at the highest risk of disease-specific mortality, in the management of patients with RAI-refractory disease, in clinical trials of novel targeted therapies in patients with advanced metastatic disease, and in the evaluation of thyroid nodules with indeterminate fine-needle aspiration for cytology. However, several controversies remain to be resolved, namely: the cutoff value of Tg in the selection of DTC patients for FDG-PET/CT, whether FDG-PET/CT scanning should be performed under thyrotropin stimulation or suppression, and the clinical significance of thyroid FDG-PET/CT incidentalomas. The aim of the present article is to provide an overview of the data about the molecular basis for, clinical indications of, and controversies related to the use of FDG-PET/CT in patients with DTC.
Assuntos
Carcinoma/diagnóstico , Neoplasias da Glândula Tireoide/diagnóstico , Carcinoma/metabolismo , Carcinoma/terapia , Fluordesoxiglucose F18/metabolismo , Humanos , Radioisótopos do Iodo/metabolismo , Radioisótopos do Iodo/uso terapêutico , Imagem Multimodal , Tomografia por Emissão de Pósitrons , Compostos Radiofarmacêuticos/metabolismo , Compostos Radiofarmacêuticos/uso terapêutico , Neoplasias da Glândula Tireoide/metabolismo , Neoplasias da Glândula Tireoide/terapia , Tireoidectomia , Tomografia Computadorizada por Raios X , Imagem Corporal TotalRESUMO
BACKGROUND: Papillary thyroid cancer accounts for approximately 80% of thyroid tumors and its incidence has increased over the past decades. Papillary thyroid microcarcinomas (PMCs), defined by the World Health Organization as less than 1.0 cm in size, are identified with greater frequency. The majority of patients with PMCs follows a benign clinical course, however a subgroup of these carcinomas is as aggressive as bigger tumors. Risk factors related with poor outcome have not been defined and the optimal treatment has not been proved. The authors investigated histologic prognostic factors predicting high risk patients considered for more aggressive treatment and propose reviewed therapeutic guidelines based on analysis of histopathologic features which determined the recurrence rate. STUDY DESIGN: One hundred forty nine patients with PMC who underwent surgery were retrospectively analyzed. Clinical and histopathologic parameters potentially predicting patient outcome and recurrent disease were statistically investigated, after a minimum follow-up of 5 years. RESULTS: After a median follow-up of 5.4 years 28 of 149 patients experienced recurrent disease. All of them were reoperated on and newly treated with radioiodine administration. The multivariate statistical analysis identified extrathyroidal invasion (Odds Ratio, OR, 58.54; P=0.013), the solid pattern (OR,25.77; P>0.001), the tumor multifocality (OR, 15.80; P= 0.005), and the absence of tumor capsule (OR, 9.74; P=0.015) as significant and indipendent risk factors for the appearance of PMCs recurrences. Of note, none of the PMC "incidentally" discovered at histopathological examination alone experienced recurrent disease during follow-up. CONCLUSIONS: Although most PMC have favourable long-term prognosis, some patients (19% in our series) presented aggressive clinical course strongly correlated with some histopathologic features (extrathyroidal invasion, tumor multifocality, solid pattern and absence of capsule) who need to be investigated and for whom a radical therapeutic approach is recommended based on total thyroidectomy and regional lymphadenectomy followed by radioiodine administration.