Combined Treatment with Laser Ablation and Tyrosine-Kinase Inhibitor as A Novel Multimodality Approach to Locally Advanced Thyroid Cancer: A Case Report.

BACKGROUND: Direct locoregional treatments were recently proposed for the local control of cervical and distant metastasis of thyroid cancer, but data on their use as part of a multimodality approach for primary thyroid tumors are poor. In this feasibility study, laser ablation (LTA) was successfully used for the initial debulking of unresectable radioiodine-refractory thyroid cancer in sequential therapy with Tyrosine-Kinase Inhibitors (TKI). CASE PRESENTATION: A 69-year-old woman underwent partial resection of papillary thyroid cancer with extensive tracheal infiltration. Post-treatment whole-body scan (131I, 8140 MBq) showed the absence of cervical thyroid uptake. The patient experienced a rapid increase in her cervical mass associated with dysphonia, dyspnea, and dysphagia. Due to a concomitant severe hypertensive state and cardiac failure, the patient was treated with LTA after a multidisciplinary consultation. After local anesthesia, two 300 nm optic fibers were inserted into the lesion through 21G spinal needles. Two illuminations with 4-watt output power and 3600 Joules energy delivery were performed with a diode-laser source. LTA resulted in rapid cancer debulking, and mass volume decreased from 23.9 to 7.5 mL resulting in significant improvement of pressure symptoms. Three months later, the patient was started on lenvatinib due to the initial regrowth of the tumor mass. The cervical tumor burden was controlled by TKI for 20 months when a rapid disease progression occurred, and the patient died. DISCUSSION: Locally advanced, unresectable, and radioiodine-refractory thyroid tumors can be managed with a novel multimodality approach. The initial debulking with LTA of the locally aggressive disease results in rapid control of the tumor burden threatening patients' life and is effectively followed by long-term control with TKI treatment. CONCLUSION: Based on this experience, sequential multimodality treatment with an initial locally directed laser ablation procedure followed by TKI therapy may be considered as a salvage option in patients with unresectable and rapidly progressive RR thyroid tumors.

High-intensity focused ultrasound (HIFU) therapy for benign thyroid nodules: a 3-year retrospective multicenter follow-up study.

BACKGROUND: Outcomes of high-intensity focused ultrasound (HIFU), as a non-surgical treatment option for benign symptomatic thyroid nodules, has mainly been based on single-center studies and short-term follow-up. Therefore, we assessed the safety, and long-term efficacy of HIFU in benign thyroid nodules among four centers with expertise in thyroid mini-invasive procedures. PATIENTS AND METHODS: Retrospective three year follow-up study in four European centers, treating solid benign thyroid nodules causing pressure symptoms and/or cosmetic concerns. Nodule volume reduction was assessed at 1, 3, 6, 12, 24, and 36 months post-treatment. Technical efficacy, defined as a volume reduction rate (VVR) >50% was evaluated at 6, 12, 24 and 36 months. Predictive factors of efficacy were assessed using logistic models. Complications and side effects were classified according to the Interventional Radiology Guidelines and changes in local symptoms were scored on a visual-analog scale. RESULTS: Sixty-five patients (mean age 51.1 ± 14.0 years; 86.2% women) with a single thyroid nodule and a mean baseline nodule volume of 9.8 ± 10.3 mL were treated with a mean energy of 7.1 ± 3.1 kJ (range: 2.0 to 15.5 kJ). Median nodule volume reduction was 31.5% (IQR: -38.6% to -23.1%) at 12 months and 31.9% (IQR: -36.4% to -16.1%) at 36 months. Technical efficacy was obtained in 17.2% of cases at 6 months, 17.8% at 12 months, 3.4% at 24 months, and 7.4% at 36 months. The number of treated pixels and the mean energy delivered were positively correlated to VRR at 1, 6 and 12 months. The risk of treatment failure decreased by 4.3% for each additional unit of energy delivered. The procedure duration was inversely correlated with treatment failure (OR 1.043, 95% CI: 1.011-1.083; p = 0.014). Improvement of cervical pressure symptoms or cosmetic complaints were observed in less than 15% of the cases at 12, 24 and 36 months. Horner's syndrome occurred in one case (1.5%) and minor complications, not requiring treatment, in three (4.6%) patients. No change in thyroid function was registered. CONCLUSIONS: HIFU carried a low risk of complications. A single treatment resulted in a 30-35% thyroid nodule volume decrease within one year, reduction that remained stable for 2 years. Outcomes varied significantly between centers with different HIFU expertise. Focus on improved HIFU technology, adequate training, and appropriate selection of patients is needed to achieve efficacy comparable to other thermal ablation procedures.

Inter- and Intraobserver Agreement in the Assessment of Thyroid Nodule Ultrasound Features and Classification Systems: A Blinded Multicenter Study.

Background: Single-center trials demonstrated moderate-substantial level of interobserver agreement in the evaluation of ultrasound (US) features of thyroid nodules. Multicenter studies on US agreement, however, are scanty, and data on intraobserver agreement are poor. Aim of the study was to assess inter- and intraobserver agreement between different thyroid centers and different specialists. Methods: A blinded analysis of 100 electronically recorded thyroid nodule US images was conducted in three large-volume thyroid centers by seven radiologists and endocrinologists. The evaluation was repeated after randomization 4 months later. The following US characteristics were evaluated: composition, echogenicity, margins, intranodular echogenic spots, vascularity, and shape. Thyroid nodules were also classified according to AACE/ACE/AME, EU-TIRADS, ATA, and ACR-TIRADS US classifications. Intra- and interobserver agreement was calculated using cross-tabulation expressed as mean Cohen's Kappa. Results: Interobserver agreement for US features: K-coefficient was 0.53 for composition, 0.47 for echogenicity, 0.46 for intranodular vascularity, and 0.33 for margins of the nodules. For echogenic foci, the K-coefficient was 0.47 for microcalcifications, 0.38 for macrocalcifications, 0.11 for the subcategory comet-tail artifacts, and 0.42 for shape. Operators resulted uncertain on hyperechoic foci definition in 16% of cases and described them as "hyperechoic foci of uncertain significance." Interobserver Cohen-K for US classification systems was 0.44 for AACE, 0.42 for ACR-TIRADS, 0.39 EU-TIRADS, and 0.34 for ATA. Intraobserver agreement: the K-coefficient for nodule US features was 0.62 for intranodular vascularity, 0.58 for composition, 0.60 for echogenicity, 0.54 for macrocalcifications, 0.55 for microcalcifications, 0.47 for comet tails, 0.39 for margins, and 0.35 for shape. Intraobserver Cohen-K for US classification systems was 0.54 for AACE, 0.49 for ACR-TIRADS, 0.38 for ATA, and 0.33 for EU-TIRADS. Conclusions: Intraobserver reproducibility for thyroid nodule US reporting and US classification systems appears fairly adequate, while the interobserver agreement between different centers is lower than that assessed in single-center trials. Reporting and rating ability of thyroid US examiners still appear not consistent. An unified lexicon of thyroid US features, a simplified method of classification, and a dedicated training in the description of thyroid US findings may increase the observers' agreement and the predictive value of US classification systems in real world practice.

Ultrasound-guided laser ablation for local control of neck recurrences of medullary thyroid cancer. A feasibility study.

BACKGROUND: Surgery is the standard treatment for cervical metastases of medullary thyroid cancer (MTC) diagnosed after initial surgical treatment. Repeated neck dissections, however, carry an elevated risk of complications, have an adverse impact on the quality of life, and sometimes do not achieve cure of the disease Clinical case: In a patient who had undergone two cervical neck dissections complicated by accessory nerve injury, an US-guided laser ablation (LA) of a lymph node metastasis of MTC was performed. LA was performed with two treatments during a five month period. The procedure was carried out with one optical fiber and an energy delivery of 3300 and 360 Joules. Treatments were well tolerated and resulted in complete structural and biochemical cure during a 12 month follow-up. No major complication was registered. CONCLUSIONS: LA is a promising tool for the management of relapsing cervical metastases that are localized in non- critical areas and are characterized by low progression rate. Advantages of LA are the outpatient setting, the absence of general anesthesia, the tolerability and the safety of the procedure. Thus, LA may be considered as an alternative approach to surgery or active surveillance for the management of local recurrences of MTC in selected patients.

Predictive Value of Malignancy of Thyroid Nodule Ultrasound Classification Systems: A Prospective Study.

Context: British Thyroid Association (BTA), American Thyroid Association (ATA), and American Association of Clinical Endocrinologists (AACE/ACE/AME) recommend for thyroid nodules an ultrasound (US)-based stratification of risk of malignancy. Aim of our study was to assess the diagnostic accuracy of US classification systems and their reliability for indication to fine-needle aspiration (FNA). Design: Prospective study on 987 thyroid nodules consecutively referred for FNA. US images were independently reviewed by four experts for assignment of malignancy risk. Cytologically benign nodules had confirmation with a second FNA, whereas Bethesda class IV, V, and VI nodules were operated upon. Class III nodules had surgery or follow-up on the basis of clinical, immunocytochemical, and US features. Results: BTA: Malignancy rate was 2.8% in benign, 10.0% in indeterminate, 51.3% in suspicion, and 80.9% in malignant US class. Sensitivity was 0.74, specificity was 0.92, and accuracy was 0.89. ATA: Malignancy rate was 0.0% in benign, 2.2% in very low suspicion, 3.0% in low suspicion, 5.8% in intermediate, and 55.0% in high suspicion US class. Sensitivity was 0.81, specificity was 0.87, and accuracy was 0.86. AACE/ACE/AME: Malignancy rate was 1.1% in low-risk, 4.4% in intermediate-risk, and 54.9% in high-risk US class. Sensitivity was 0.82, specificity was 0.87, and accuracy was 0.86. K correlation coefficient was 78.9%, 76.9%, and 82.0% for BTA, ATA, and AACE/ACE/AME classifications. Conclusions: Classification systems had elevated predictive value of malignancy in high-risk classes. ATA and AACE/ACE/AME systems were effective for ruling out indication to FNA in low-US-risk nodules. A similar diagnostic accuracy and a substantial interobserver agreement was provided by the three- and the five-category classifications.

Percutaneous ultrasound-guided laser ablation is effective for treating selected nodal metastases in papillary thyroid cancer.

CONTEXT: Mini-invasive procedures may be useful for control of local neck nodal metastases of papillary thyroid cancer (PTC) in high-risk patients. OBJECTIVE: Our objective was to assess the effectiveness and safety of ultrasound (US)-guided laser ablation (LA) for nonsurgical treatment of small-size neck metastases of PTC. DESIGN AND SETTING: We conducted a pilot study on a surgically controlled metastasis, followed by a prospective trial with a 12-month follow-up. PARTICIPANTS: Participants included five patients with previous total thyroidectomy and neck dissection for PTC, with eight new lymph node metastases in an area already treated with surgical dissection and lymph node volume less than 2 ml and absent radioiodine uptake. OUTCOME MEASURES: We evaluated thyroglobulin (Tg) and US changes of the lymph nodes 6 and 12 months after LA as well as tolerability and side effects of the procedure. RESULTS: A single LA treatment induced progressive volume reduction of the eight metastatic lymph nodes. Mean baseline volume decreased from 0.64 ± 0.58 to 0.07 ± 0.06 ml at 12-month control. Mean volume reduction was 64.4 ± 0.19% at 6 months (P < 0.02 vs. baseline) and 87.7 ± 0.11% at 12 months (P < 0.01 vs. baseline). No regrowth was registered. Mean serum Tg on LT4 decreased from 8.0 ± 3.2 ng/ml to 2.0 ± 2.5 ng/ml at 12-month control (P < 0.02 vs baseline). In three patients (60%) Tg levels were undetectable at 12-month control. Pain was tolerable in two cases and mild in three cases. Transient dysphonia in one patient was the only complication. After 1 yr, no cancer seeding was present. CONCLUSION: LA is a well-tolerated outpatient procedure that results in a rapid cytoreduction of cervical nodal metastases of PTC. Mini-invasive procedures may be used in lieu of surgery as an adjunctive therapy for small-burden local/regional disease recurrence. They are occasionally associated with an anatomical or biochemical cure, but long-term follow-up or controlled trials are needed.

Ultrasound-guided laser ablation of incidental papillary thyroid microcarcinoma: a potential therapeutic approach in patients at surgical risk.

BACKGROUND: Incidental papillary thyroid microcarcinoma (PTMC), a frequent clinical problem, is usually associated with a favorable outcome. During long-term follow-up, only a minority of cases show aggressive behavior with either lymph node or distant metastases. Recently, we had an opportunity to evaluate the efficacy of nonsurgical, ultrasound (US)-guided percutaneous laser ablation (PLA) for local treatment of PTMC in an otherwise inoperable patient. PATIENT AND METHODS: Neck US examination revealed an incidental, solitary, 8 × 7 × 7 mm hypoechoic nodule with microcalcifications of the right thyroid lobe. The patient suffered from decompensated liver cirrhosis, renal failure, and recent surgery followed by external beam radiation therapy for breast cancer. Cytologic diagnosis showed papillary thyroid carcinoma, but the patient declined surgery because of high risk of thyroid surgery. After local anesthesia with 2% xylocaine, PLA was performed according to the previously reported procedure with an Nd:YAG laser. SUMMARY: The procedure was well tolerated, without side effects, and the patient required no analgesics. US-guided fine-needle aspiration biopsy and core-needle biopsy were performed at 1 and 12 months after PLA, which demonstrated necrotic material and inflammatory cells with no viable neoplastic cell. At the 24 months US follow-up examination, the area of necrosis further decreased, demonstrating a 4 × 4 mm hypoechoic zone and a small hyperechoic area due to fibrotic changes. A fine-needle aspiration biopsy confirmed the absence of malignant cells. CONCLUSIONS: Laser-induced thermal ablation was a safe and effective ablative treatment for a patient with PTMC confined to the thyroid gland who was at high surgical risk. This approach should be considered only in elderly patients and/or in those with comorbidities that might expose the patients to an undue high surgical risk and only after the evaluation by neck US, computed tomography, magnetic resonance imaging, or positron emission tomography/computed tomography rules out lymph-node involvement or metastatic disease.

Fabrication and testing of l = 2 optical vortex phase masks for coronography.

In this paper we present the fabrication process and tests of two different types of l = 2 spiral phase plates (SPPs), designed for an Optical Vortex Coronagraph (OVC) in the visible wavelength regime. Each phase mask is realized dividing the spirals area in sectors respectively of 8 and 512 of levels using lithographic nanofabrication approach. The SPPs produces different optical vortices (OVs) with topological charge l that depends on the number of steps and on the wavelength. We found that the residual light in the central dark region of the OV tends to zero as the number of steps increases.

Treatment of benign cold thyroid nodules: a randomized clinical trial of percutaneous laser ablation versus levothyroxine therapy or follow-up.

AIM OF THE STUDY: To compare clinical and ultrasound (US) changes induced in cold thyroid nodules by US-guided percutaneous laser ablation (PLA) versus follow-up or levothyroxine (LT4) suppressive therapy. METHODS: 62 patients randomly assigned to a single PLA (Group 1), LT4 (Group 2), or follow-up (Group 3). Entry criteria: euthyroid patients with a solid thyroid nodule >5 mL and benign cytological findings. TREATMENT: Group 1: PLA was performed with a 1.064 mum neodymium yttrium-aluminum-garnet laser with output power of 3 W for 10 minutes; Group 2: the LT4 dose was adjusted to induce thyrotropin suppression; Group 3: no treatment. RESULTS: In Group 1 a significant nodule reduction was found 6 and 12 months after PLA (delta volume: -42.7 +/- 13.6%; p = 0.001). A reduction >50% was found in 33.3% of cases. In Group 2 a nonsignificant nodule shrinkage was observed. A nonsignificant volume increase was observed in Group 3. Improvement of local symptoms was registered in 81.2% of patients in Group 1 vs. 13.3% in Group 2 and 0.0% in Group 3 ( p = 0.001). No complications were noted. CONCLUSIONS: A single PLA induced significant volume reduction and improvement of local symptoms. PLA was more effective than LT4. Follow-up was associated with nodule growth and progression of local symptoms. PLA should be considered a potential mini-invasive alternative to surgery in symptomatic patients with benign cold thyroid nodules.

Analysis of factors predicting survival in patients with hepatocellular carcinoma treated with percutaneous laser ablation.

BACKGROUND/AIMS: The factors which predict the long-term outcome in patients with hepatocellular carcinoma who are treated with percutaneous laser ablation (PLA) are not well established. METHODS: We prospectively analyzed treatment and survival parameters of 148 cirrhotic patients with nonsurgical hepatocellular carcinoma who had undergone PLA at a single institution during an 11-year period. RESULTS: Single tumors were seen in 129 of 148 (87%) patients, and 2-3 nodules were seen in 19 (13%) patients, for a total of 169 tumors. The median overall time survival was 39 months (95% confidence interval [CI], 30-47 months). The 1-, 2-, 3-, 4-, and 5-year cumulative survival rates were 89, 75, 52, 43, and 27%, respectively. From multiple regression analysis, the independent predictors of survival were found to be tumor grading (P=0.002; risk ratio [RR] 0.37, 95% CI 0.20-0.70), bilirubin levels < or =2.5mg/dl (P=0.014; RR 1.58, 95% CI 1.09-2.28), and the achievement of complete tumor ablation (P=0.020; RR 0.53, 95% CI 0.31-0.90). An initial complete tumor ablation was the only factor associated with longer survival in patients with Child-Turcotte-Pugh class A cirrhosis (P=0.012; hazard ratio [HR] 0.48, 95% CI 0.23-1.03). CONCLUSIONS: A complete tumor ablation results in improved survival in all patients with nonsurgical hepatocellular carcinoma. Ideal candidates for PLA are those with a well-differentiated histology, and normal bilirubin levels.

Percutaneous laser ablation in the treatment of hepatocellular carcinoma with small tumors: analysis of factors affecting the achievement of tumor necrosis.

PURPOSE: To identify the factors that affect the achievement of tumor necrosis with percutaneous laser ablation (PLA) in patients with hepatocellular carcinoma (HCC) and tumor size no larger than 4.0 cm. MATERIALS AND METHODS: Ultrasound-guided biopsy results were retrospectively studied in 99 lesions (range, 0.5-4.0 cm; mean, 2.7 cm) from 82 patients (44 men, 38 women; age range, 50-80 years; median, 68 y) who had undergone PLA. RESULTS: Complete tumor ablation was obtained in 90 lesions (90.9%). Of the nine cases in which complete tumor necrosis was not achieved, six had tumors located in sites that did not allow the optimal placement of fibers, and five of these had a tumor diameter greater than 3 cm. Early discontinuation of PLA as a result of decompensation of liver cirrhosis was the reason for not achieving a complete tumor ablation in three other cases. There was a clear relationship between the energy delivered and the volume of necrosis achieved (r = 0.56; P < .001) regardless of the initial size of HCC tumors. The number of illuminations required, and consequently the amount of energy delivered, was also affected by tumor location. In fact, lesions adjacent to large vessels (> or = 3 mm) required a greater number of illuminations than the other lesions to achieve complete ablation (2.9 +/- 1.4 vs 2.3 +/- 0.9; P = .043). The eight cases with undifferentiated histology required more illuminations than the cases with other histologic types (3.4 +/- 0.9 vs 2.2 +/- 0.9; P < .001). However, these cases were located in sites that did not allow the optimal placement of fibers, therefore requiring multiple treatments. CONCLUSION: PLA is a highly effective treatment in HCC with a tumor size of 4.0 cm or smaller. In this setting, two variables, tumor size and tumor location, affect the achievement of complete tumor ablation and the number of treatments required to obtain tumor necrosis.

Thyroid tissue: US-guided percutaneous laser thermal ablation.

PURPOSE: To evaluate in vivo the safety and effectiveness of percutaneous laser thermal ablation (LTA) in the debulking of thyroid lesions. MATERIALS AND METHODS: Twenty-five adult patients at poor surgical risk with cold nodules (n = 8), autonomously hyperfunctioning thyroid nodules (n = 16), or anaplastic carcinoma (n = 1) underwent LTA. One to four 21-gauge spinal needles were inserted with ultrasonographic (US) guidance into the thyroid lesions. A 300-microm-diameter quartz optical fiber was advanced through the sheath of the needle. Nd:YAG laser was used with output power of 3-5 W. Side effects, complications, and clinical and hormonal changes were evaluated at the end of LTA and during follow-up. Linear regression analysis was used to investigate the correlation between energy delivered and reduction in nodule volume. Volume of induced necrosis and reduction in nodule volume were assessed with US or computed tomography. RESULTS: LTA was performed without difficulties in 76 LTA sessions. After treatment with 5 W, two patients experienced mild dysphonia, which resolved after 48 hours and 2 months. Improvement of local compression symptoms was experienced by 12 of 14 (86%) patients. Thyroid-stimulating hormone (TSH) was detectable in five of 16 (31%) patients with hyperfunctioning nodules at 6 months after LTA. Volume of induced necrosis ranged from 0.8 to 3.9 mL per session. Anaplastic carcinoma treated with four fibers yielded 32.0 mL of necrosis. Echo structure and baseline volume did not influence response. Energy load and reduction in nodule volume were significantly correlated (r(2) =.75, P <.001). Mean nodule volume reduction at 6 months in hyperfunctioning nodules was 3.3 mL +/- 2.8 (62% +/- 21.4 [SD]) and in cold nodules was 7.7 mL +/- 7.5 (63% +/- 13.8). CONCLUSION: LTA may be a therapeutic tool for highly selected problems in the treatment of thyroid lesions.

Percutaneous ethanol injection treatment in benign thyroid lesions: role and efficacy.

GOAL: To establish the role of percutaneous ethanol injection (PEI) treatment in benign thyroid lesions by evaluating: (1) the long-term efficacy and side effects of the treatment, (2) the factors predictive of efficacy of PEI, and (3) the cost effectiveness of the procedure. MATERIALS AND METHODS: Fifty-eight recurrent cystic nodules, 95 autonomously functioning nodules (AFTN), and 17 hyperfunctioning nodules causing thyrotoxicosis (toxic nodules) were treated by PEI from 1990 to 1996 in our center. Ultrasound (US) and color flow doppler (CFD) examinations were carried out before and after each treatment. In patients with AFTN, serum thyrotropin (TSH), free triiodothyronine (FT3), free thyroxine (FT4), thyroid peroxidase antibody (TPOAb) levels were tested before and after PEI. All patients were independently reexamined by two external reviewers after a minimum follow-up of 5 years (median, 6.9 years). RESULTS: The median number of treatments was 2.0 (range, 1.0-4.0) for cystic nodules, 4 (range, 2.0-6.0) for AFTN, and 5 (range, 3.0-7.0) for toxic nodules. At the 5-year evaluation cystic nodules showed a volume reduction greater than 75% versus baseline in 86.2% of cases and an improvement of local symptoms in 91.4% of cases. AFTN presented serum TSH within normal limits in 60.0% of patients. Toxic nodules showed a detectable serum TSH and normal FT3 and FT4 values in 35.3% of cases. Two cases of transient dysphonia were observed. In cystic lesions no significant correlation was found between the baseline and the final volume (r2 = 0.17) and no significant predictor of treatment efficacy was found. However, unilocularity was associated with a lower number of treatments than multilocularity (median, 2.0 vs. 3.0). Independent predictors of clinical efficacy in both AFTN and toxic nodules were a baseline volume less than 5.0 mL and a fluid component greater than 30% (odds ratio [OR] = 6.1 and 3.3, respectively). CONCLUSIONS: Most recurrent cystic lesions of the thyroid can be cured by PEI, which should become the first line of treatment. The majority of AFTN and toxic nodules with volume less than 5.0 mL presented a marked volume decrease and normal serum TSH levels when treated by PEI, which seems a valid alternative to clinical follow-up alone in patients refusing 131I. PEI is not indicated in large or toxic nodules, for which 131I is the treatment of choice.

Risk of malignancy in nonpalpable thyroid nodules: predictive value of ultrasound and color-Doppler features.

The aim of the study was to correlate the sonographic [ultrasound (US)] and color-Doppler (CFD) findings with the results of US-guided fine needle aspiration biopsy (FNA) and of pathologic staging of resected carcinomas to establish: 1) the relative importance of US features as risk factors of malignancy; and 2) a cost-effective management of nonpalpable thyroid nodules. Four hundred ninety-four consecutive patients with nonpalpable thyroid nodules (8-15 mm) were evaluated by US, CFD, and US-FNA. Ninety-two patients with inadequate cytology were excluded from the study. All patients with suspicious or malignant cytology underwent surgery, whereas subjects with benign cytology had clinical and US control 6 months later. Thyroid malignancies were observed in 18 of 195 (9.2%) solitary thyroid nodules and in 13 of 207 (6.3%) multinodular goiters. Cancer prevalence was similar in nodules greater or smaller than 10 mm (9.1 vs. 7.0%). Extracapsular growth (pT(4)) was present in 35.5%, and nodal involvement in 19.4% of neoplastic lesions, with no significant differences between tumors greater or smaller than 10 mm. At US cancers presented a solid hypoechoic appearance in 87% of cases, irregular or blurred margins in 77.4%, an intranodular vascular pattern in 74.2%, and microcalcifications in 29.0%. Irregular margins (RR 16.83), intranodular vascular spots (RR 14.29), and microcalcifications (RR 4.97) were independent risk factors of malignancy. FNA performed on hypoechoic nodules with at least one risk factor was able to identify 87% of the cancers at the expence of cytological evaluation of 38.4% of nonpalpable lesions. The majority of nonpalpable thyroid tumors can be identified by cytological evaluation of lesions presenting hypoechoic appearance in conjunction with one independent risk factor. Due to the nonnegligible prevalence of extracapsular growth and nodal metastasis, US-FNA should be performed on all 8-15 mm hypoechoic nodules with irregular margins, intranodular vascular spots or microcalcifications. Nonpalpable lesions of the thyroid without risk factors should be followed by means of clinical and US evaluation.