Thyroid lesions incidentally detected by (18)F-FDG PET-CT - a two centre retrospective study

Clinical implications of non-breast cancer related findings on FDG-PET/CT scan prior to neoadjuvant chemotherapy in patients with breast cancer

PURPOSE

Breast cancer (BC) patients undergoing FDG-PET/CT scans for neoadjuvant chemotherapy (NAC) may have additional non-BC related findings. The aim of this study is to describe the clinical implications of these findings.

METHODS

We included BC patients who underwent an FDG-PET/CT scan in our institute between 2011-2020 prior to NAC. We focused on patients with an additional non-BC related finding (i.e. BC metastases were excluded) for which diagnostic work-up was performed. Information about the diagnostic work-up and the clinical consequences was retrospectively gathered. A revision of all FDG-PET/CT scans was conducted by an independent physician to assess the suspicion level of the additional findings.

RESULTS

Of the 1337 patients who underwent FDG-PET/CT, 202 patients (15%) had an non-BC related additional finding for which diagnostic work-up was conducted, resulting in 318 examinations during the first year. The non-BC related findings were mostly detected in the endocrine region (26%), gastro-intestinal region (16%), or the lungs (15%). Seventeen patients (17/202: 8%, 17/1337: 1.3%) had a second primary malignancy. Only 8 patients (8/202: 4%, 8/1337: 0.6%) had a finding that was considered more prognosis-determining than their BC disease. When revising all FDG-PET/CT scans, 57 (202/57: 28%) of the patients had an additional finding categorized as low suspicious, suggesting no indication for diagnostic work-up.

CONCLUSION

FDG-PET/CT scans used for dissemination imaging in BC patients detect a high number of non-BC related additional findings, often clinically irrelevant and causing a large amount of unnecessary work-up. However, in 8% of the patients undergoing diagnostic work-up for an additional finding, a second primary malignancy was detected, warranting diagnostic attention in selected patients.

Risk of malignancy in incidental oropharyngeal lesions exhibiting fluorodeoxyglucose uptake which proceed to tissue biopsy

BACKGROUND

Utilization of positron emission tomography/computed tomography (PET/CT) with fluorodeoxyglucose is increasing in use for a variety of indications, including surveillance of cancer patients. There is a paucity of evidence pertaining to the significance of incidental PET-avid oropharyngeal lesions. This study aims to examine the clinical and radiological features of these incidental oropharyngeal lesions in patients undergoing PET for indications other than head and neck cancer.

METHODS

Retrospective cohort study of three Australian tertiary hospitals, from 2015 to 2021, on adult patients undergoing biopsy of incidental PET-avid oropharyngeal lesions. Primary outcome of interest was the incidence of malignancy. Patients with a previous history of, or undergoing investigations for, head and neck cancer were excluded.

RESULTS

Thirty-one patients were included, wherein 21 patients had tonsillar uptake, and 13 patients had base of tongue uptake. Tonsillar disease was mostly asymmetrical (n = 15/21), bilateral (n = 11/21), and had median SUVmax 9.35 (n = 12, IQR 7.4-11.15). Base of tongue was mostly asymmetrical (n = 7/13, 54%), bilateral (n = 8/13, 62%), and had median SUVmax 8.2 (n = 10, IQR 6.9-12.65). Seven patients had malignancy confirmed on tissue biopsy: five biopsies confirmed the tissue diagnosis of suspected lymphoma, and two incidental findings of unexpected malignancies: one p16 positive tonsillar squamous cell carcinoma, and one metastatic breast cancer.

CONCLUSION

In 31 patients undergoing tissue biopsy for incidental PET-avid oropharyngeal lesions, there were two unexpected malignancies. Our study results indicate that although unexpected malignancies are uncommon, a malignant diagnosis cannot be excluded from clinical features alone.

PET/CT May Assist in Avoiding Pointless Thyroidectomy in Indeterminate Thyroid Nodules: A Narrative Review

Indeterminate thyroid nodules (ITN) are commonly encountered among the general population, with a malignancy rate of 10 to 40%. However, many patients may be overtreated with futile surgery for benign ITN. To avoid unnecessary surgery, PET/CT scan is a possible alternative to help differentiate between benign and malignant ITN. In this narrative review, the major results and limitations of the most recent studies on PET/CT efficacy (from PET/CT visual assessment to quantitative PET parameters and recent radiomic features analysis) and on cost-effectiveness (compared to other alternatives (such as surgery)) are presented. PET/CT can reduce futile surgery with visual assessment (around 40%; if ITN ≥ 10 mm). Moreover, PET/CT conventional parameters and radiomic features extracted from PET/CT imaging can be associated together in a predictive model to rule out malignancy in ITN, with a high NPV (96%) when certain criteria are met. Even though promising results were obtained in these recent PET/CT studies, further studies are needed to enable PET/CT to become the definitive diagnostic tool once a thyroid nodule is identified as indeterminate.

MANAGEMENT PRINCIPLES OF INCIDENTAL THYROID 18F-FDG UPTAKE IDENTIFIED ON 18F-FDG PET/CT IMAGING

PURPOSE

The purpose of this study is to determine the clinical significance of incidental thyroid 18F-FDG PET/CT uptake in oncology patients with the focus achieving the most appropriate management of this challenging situation.

MATERIALS AND METHOD

Two thousand five hundred and eighty 18F-FDG PET/CT studies performed at our institute in the past 4 years were retrospectively reviewed. Patients with incidental FDG uptake in the thyroid gland were further analysed.

RESULTS

The prevalence of incidental FDG uptake in thyroid gland was 7.6% (129 patients). 26 patients (20.1%) had diffuse 18F-FDG PET/CT uptake, 103 patients (79.1%) had nodular uptake in thyroid gland. All diffuse uptake patients who were further examined diagnosed to be a benign condition. 53 patients in the nodular uptake group were further examined and the final histopathology examinations revealed an 18.8% malignancy rate. SUV max values ranged from 2 to 21.8 with a significant highness in malignant lesions.

CONCLUSION

18F-FDG PET/CT uptake in the thyroid gland may be diffuse or nodular. Diffuse uptake needs no further examination as it usually accompanied by benign thyroid disorders. Patients with nodular uptake whose general condition is good should be further examined due to high rates of malignancy.

The dilemma of 18F-FDG PET/CT thyroid incidentaloma: what we should expect from FNA. A systematic review and meta-analysis

PURPOSE

¹⁸F-FDG thyroid incidentaloma (TI) occurs in ~2% of PET/CT examinations with a cancer prevalence of up to 35-40%. Guidelines recommend fine-needle aspiration cytology (FNA) if a focal ¹⁸F-FDG TI corresponds to a sonographic nodule >1 cm. The aim of this systematic review and meta-analysis was to provide evidence-based data on the diagnostic distribution of ¹⁸F-FDG TIs in the six Bethesda systems for reporting thyroid cytopathology (BETHESDA) subcategories.

METHODS

Original studies reporting ¹⁸F-FDG TIs and cytologically classified according to BETHESDA were included. Six separate meta-analyses were performed to obtain the pooled prevalence (95% confidence interval, 95% CI) of ¹⁸F-FDG TIs in the six BETHESDA subcategories.

RESULTS

Fifteen studies were finally included. Nine studies were from Asian/Eastern and six from Western countries. FNA data according to BETHESDA was available in 2304 cases. The pooled prevalence of ¹⁸F-FDG TIs according to BETHESDA was BETHESDA I 10% (6-14), BETHESDA II 45% (37-53), BETHESDA III 8% (3-13), BETHESDA IV 8% (5-12), BETHESDA V 6% (4-9), BETHESDA VI 19% (13-25). A significantly different prevalence was found in the BETHESDA IV between Asian/Eastern (2%) and Western (19%) studies.

CONCLUSION

Two-thirds of focal ¹⁸F-FDG TIs undergoing FNA have either malignant (BETHESDA VI) or benign (BETHESDA II) cytology while a minority will have indeterminate (BETHESDA III or IV) FNA results. Significant differences between Asian/Eastern and Western studies are also present in the prevalence of indeterminate FNA results.

Characteristics of malignant thyroid lesions on [18F] fluorodeoxyglucose (FDG)-Positron emission tomography (PET)/Computed tomography (CT)

Objectives

To determine the imaging variables that can best differentiate malignant from benign thyroid lesions incidentally found on F-18 FDG PET/CT scans.

Methods

All F-18 FDG PET/CT studies starting from 2011 to end of 2016 were reviewed for incidental thyroid lesions or metabolic abnormalities. Only patients who were found to have FNAB or histopathology were included. Patients with known thyroid malignancy were excluded. Patients were analyzed for age, sex, SUVmax, non-enhanced CT tissue density in mean Hounsfield units (HU), uptake pattern (focal or diffuse) and gland morphology (MNG or diffuse). A control group of 15 patients with normal thyroid glands were used to assess the tissue density in HU for normal thyroid tissue. Sensitivity, specificity, PPV, NPV and accuracy to detect malignancy were calculated. Pearson Chi-square test was used to compare categorical variables while unpaired T-test and one way ANOVA test were used to compare means of continuous variables. ROC analysis was used to assess the best cut off points for SUVmax and HU. Regression analysis was used to detect the independent predictors for malignant lesions.

Results

Biopsy was unsatisfactory or indeterminate in 4/48 patients (8%). Only 44 patients (mean age 55.2 ± 14.7; 30 females (68 %)) with unequivocal FNAB or histopathology were included for further analysis. MNG was noted in 17/44 patients (38.6 %). Thyroid malignancy was found in 16/44 (36.4 %), benign thyroid lesions in 28/44 (63.6 %). Thyroid malignancies were 12 papillary, 1 follicular, 1 Hurthle cell neoplasm and 2 lymphoma. Benign lesions were 23 benign follicular or colloid nodules and 5 autoimmune thyroiditis. Focal FDG uptake pattern was more frequently associated with malignant lesions compared to benign lesions (75 % vs. 43 %; p = 0.039). The mean SUVmax and tissue density (HU) were both higher in malignant than benign lesions (8.8 ± 8.3 vs. 3.6 ± 1.9, p = 0.024) and (48.9 ± 12.7 vs. 32.9 ± 17.5, p = 0.003) respectively. The mean HU in the control group with normal thyroid tissue was 90 ± 7.4 significantly higher than in both the benign and malignant lesions (p < 0.001). ROC analysis revealed SUVmax cutoff of >4.7 and HU cutoff of >42 to best differentiate malignant from benign lesions. The sensitivity, specificity, PPV, NPV and accuracy to detect malignancy for SUVmax>4.7 were 68.8 %, 78.6 %, 64.8 %, 81.5 & 75.0 % (p = 0.002), for HU > 42 were 81.3.0 %, 75.0 %, 65.0 %, 87.5 & 77.3 % (p = 0.0003) and for both parameters combined were 87.5 %, 60.7 %, 56.0 %, 89.5 % and accuracy of 70.5 % (p = 0.002) respectively. Only HU > 42 and SUVmax>4.7 were independent predictors for malignancy with odd ratios 8.98 and 4.93 respectively.

Conclusion

A higher tissue density (HU > 42) and SUVmax>4.7 as well as tendency for focal uptake pattern are the most significant characteristics associated with malignant thyroid lesions occasionally detected on PET/CT.

Five-year follow-up and clinical outcome in euthyroid patients with thyroid nodules

BACKGROUND

Thyroid nodule diagnosis has become increasingly frequent. Defining optimum surveillance intervals for patients with unsuspicious thyroid nodules remains a challenge. This was a single centre cohort study in which patients diagnosed with unsuspicious thyroid nodules in whom no treatment was indicated were invited for re-evaluation 5 years after the diagnosis. The primary end point of the study was to estimate the change in nodule size with thyroid ultrasound (US) and the secondary end point was to assess the need for clinical management 5 years after the diagnosis.

PATIENTS AND METHODS

Baseline patient parameters and ultrasound characteristics of the nodules were retrospectively collected. At follow-up, thyroid ultrasound was performed.

RESULTS

A hundred and eighteen (107 women / 11 men, aged 56.8 ± 13.4 years) patients were included in the study having 203 nodules at baseline, with mean largest nodule diameter 10.5 ± 7.4 mm. After 5 years, 58 (28.6%) nodules significantly increased in size, 27 (13.3%) decreased, and for 104 (51.2%) of nodules, no change in size was noted. Fourteen (6.9%) nodules disappeared. Additional 26 new nodules (mean largest diameter 7.7 ± 5.0 mm) in 16 patients were identified at follow-up. Regarding the clinical outcome, no new thyroid cancers were found. For 107 (90.7%) patients no further management was indicated. Five (4.2%) patients were referred to thyroidectomy because of the growth of the nodules. Two (1.7%) patients were treated for hyperthyroidism. Four (3.4%) patients did not complete the study.

CONCLUSIONS

We report a single centre experience of the natural history of unsuspicious thyroid nodules. Our results showed that 71.4% of such nodules remained stable in size, decreased or even disappeared and that the vast majority of the patients remained clinically stable with no need for treatment 5 years after the diagnosis.

Focal Thyroid Incidentalomas on 18F-FDG PET/CT: A Systematic Review and Meta-Analysis on Prevalence, Risk of Malignancy and Inconclusive Fine Needle Aspiration

BACKGROUND

The rising demand for ¹⁸F-fluorodeoxyglucose positron emission tomography with computed tomography (¹⁸F-FDG PET/CT) has led to an increase of thyroid incidentalomas. Current guidelines are restricted in giving options to tailor diagnostics and to suit the individual patient.

OBJECTIVES

We aimed at exploring the extent of potential overdiagnostics by performing a systematic review and meta-analysis of the literature on the prevalence, the risk of malignancy (ROM) and the risk of inconclusive FNAC (ROIF) of focal thyroid incidentalomas (FTI) on ¹⁸F-FDG PET/CT.

DATA SOURCES

A literature search in MEDLINE, Embase and Web of Science was performed to identify relevant studies.

STUDY SELECTION

Studies providing information on the prevalence and/or ROM of FTI on ¹⁸F-FDG PET/CT in patients with no prior history of thyroid disease were selected by two authors independently. Sixty-one studies met the inclusion criteria.

DATA ANALYSIS

A random effects meta-analysis on prevalence, ROM and ROIF with 95% confidence intervals (CIs) was performed. Heterogeneity and publication bias were tested. Risk of bias was assessed using the quality assessment of diagnostic accuracy studies (QUADAS-2) tool.

DATA SYNTHESIS

Fifty studies were suitable for prevalence analysis. In total, 12,943 FTI were identified in 640,616 patients. The pooled prevalence was 2.22% (95% CI = 1.90% - 2.54%, I² = 99%). 5151 FTI had cyto- or histopathology results available. The pooled ROM was 30.8% (95% CI = 28.1% - 33.4%, I² = 57%). 1308 (83%) of malignant nodules were papillary thyroid carcinoma (PTC). The pooled ROIF was 20.8% (95% CI = 13.7% - 27.9%, I² = 92%).

LIMITATIONS

The main limitations were the low to moderate methodological quality of the studies and the moderate to high heterogeneity of the results.

CONCLUSION

FTI are a common finding on ¹⁸F-FDG PET/CTs. Nodules are malignant in approximately one third of the cases, with the majority being PTC. Cytology results are non-diagnostic or indeterminate in one fifth of FNACs. These findings reveal the potential risk of overdiagnostics of FTI and emphasize that the workup of FTI should be performed within the context of the patient's disease and that guidelines should adopt this patient tailored approach.

Risk of Malignancy in FDG-Avid Thyroid Incidentalomas on PET/CT: A Prospective Study

BACKGROUND

Due to a substantial risk of malignancy, patients with focal FDG-avid thyroid incidentalomas (FFTIs) on PET/CT are in most of Denmark referred to Head and Neck Cancer (HNC) fast track programs. The aim of this study was to determine the risk of malignancy in FFTI managed in a HNC fast track program.

METHODS

A prospective cohort study including all patients with FFTI referred to the HNC fast track program, Odense University Hospital between September 1, 2016 and August 31, 2017. Ultrasonography (US) and fine-needle aspiration biopsy (FNAB) were intended to be done in all patients. Nodules with cytology of Bethesda 1, 3, 4, 5, or 6 were planned for surgical removal.

RESULTS

A total of 104 patients were included. All patients had US and 101 patients (97%) had FNAB. Forty-two patients had benign cytology classified as Bethesda 2. The remaining 62 patients underwent surgery except from 11 patients, mainly due to comorbidity. The overall risk of malignancy for patients with FFTI referred to our HNC fast track program was calculated to be 24% (23/95) based on patients with unequivocal cytology and/or histology. The only statistically significant US characteristic to predict malignancy was the appearance of irregular margins with a sensitivity of 47% and specificity of 96%.

CONCLUSION

The risk of malignancy of FFTIs handled in our HNC fast track program is 24%.

Clinical significance of thyroid incidentalomas detected on fluorodeoxyglucose positron emission tomography scan (PETomas): An Indian experience

Thyroid incidentalomas (TIs) are being frequently detected on positron emission tomography (PET) scan. The risk of malignancy in these focal hot spots is substantially high as compared to incidentalomas detected on ultrasonography (USG)/magnetic resonance imaging/computed tomography (CT). Majority of the studies on the prevalence of TIs in PET and the risk of malignancy in them are retrospective and have had varied results. Very few prospective studies are available and very few Indian studies have been done on the subject. Hence, this study was undertaken to evaluate the clinical significance of TIs detected on fluorodeoxyglucose (FDG)-PET scan. The study included all patients undergoing FDG-PET scan for nonthyroid illness from October 2015 to October 2016. Twenty-three consecutive patients detected to have focal TI (FTI) were prospectively evaluated with detailed history and clinical examination, serum thyroid-stimulating hormone, total T4 and total T3 levels, USG neck, fine-needle aspiration cytology (FNAC), and surgery when indicated. The prevalence of FTI was 2.26%. Out of the 23 FTI cases, 19 patients agreed to undergo further evaluation and malignancy was detected in 5 patients (all papillary carcinomas) making a risk of malignancy of 26.3%. There was no significant correlation between CT attenuation characteristics and size of benign and malignant PETomas or between the maximum standardized uptake value (SUV_max) of benign and malignant PETomas. Hence, the risk of malignancy in thyroid PETomas is substantially high and warrants USG-guided FNAC and further work-up. Their SUV_maxvalues, size, and CT attenuation characteristics do not contribute in differentiating benign from malignant lesions.

18F-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography May Exclude Malignancy in Sonographically Suspicious and Scintigraphically Hypofunctional Thyroid Nodules and Reduce Unnecessary Thyroid Surgeries

BACKGROUND

The aim of this study was to evaluate whether ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) is useful in the further characterization of sonographically suspicious and scintigraphically hypofunctional thyroid nodules.

METHODS

Sixty-five patients with sonographically suspicious thyroid nodules that were hypofunctional on 99m-Tc-pertechnetate scintigraphy (diameter >1 cm) were retrospectively analyzed. All patients underwent evaluation with FDG-PET/CT. Thyroid nodules were sonographically categorized by Thyroid Image Reporting and Data System (TIRADS) criteria. FDG uptake in the thyroid nodules was visually compared to the remainder of the thyroid tissue and categorized as pathological or non-pathological. In cases of pathologically increased uptake, maximum standardized uptake values (SUVmax) of the suspicious nodule and the perinodular thyroid tissue were determined. Depending on the results of the FDG-PET/CT, patients underwent thyroid surgery (pathological FDG uptake) or follow-up examinations (non-pathological FDG uptake). The endpoints for comparison with the FDG uptake were either histological results or sonographic follow-up examinations of at least five years.

RESULTS

In 18/65 (28%) patients, PET/CT showed visually pathological FDG uptake in the suspicious thyroid nodules (SUVmax 7.1 ± 4.6). Of these nodules, 3/18 (17%) were sonographically categorized as TIRADS 4a, 11/18 (61%) nodules as TIRADS 4b, 3/18 (17%) nodules as TIRADS 4c, and 1/18 (6%) nodule as TIRADS 5. The other nodules without pathological FDG uptake were categorized as TIRADS 4a in 24/47 (51%) patients, as TIRADS 4b in 18/47 (38%), and as TIRADS 4c in 5/47 (11%) patients. Twenty-three patients (18 FDG positive, 5 FDG negative) underwent surgery. The other patients underwent follow-up examinations with stability on observation over at least five years as a surrogate endpoint. Taking into consideration that FDG-PET/CT was rated as true negative in 42/47 patients with stability on sonographic follow-up, sensitivity, specificity, positive predictive value, and negative predictive value of FDG-PET/CT in detecting malignancy in the suspicious thyroid nodules were 100%, 87%, 61%, and 100%, respectively.

CONCLUSION

FDG-PET/CT allows stratification of patients with sonographically suspicious and scintigraphically hypofunctional thyroid nodules with a positive predictive value of 61% and negative predictive value of 100%. The absence of visually pathological FDG uptake in suspicious thyroid nodules may be useful for avoiding unnecessary thyroid surgery.

Malignancy rate of focal thyroid incidentaloma detected by FDG PET-CT: results of a prospective cohort study

OBJECTIVE

To evaluate the malignancy rate of focal thyroid incidentaloma (fTI) in a population of patients undergoing a 18F-fluorodeoxyglucose positron emission tomography-computed tomography (FDG PET-CT) for a non-thyroid purpose.

DESIGN

We conducted a prospective cohort study from January 2013 to November 2014. All consecutive patients referred for a FDG PET-CT were prospectively screened. Patients with known neoplastic thyroid disease were excluded from the analysis. All patients presenting one or more fTI and who accepted to benefit from a complementary thyroid ultrasonography (US) were included and managed according to the French endocrine society consensus. Prevalence of fTI in our population and malignancy rate was assessed.

RESULTS

During the inclusion period, 10,171 patients were referred for a FDG PET-CT in our center. Fifty-three patients presenting a known thyroid disease were excluded. Among the remaining 10,118 patients, 127 (1.3%) with 131 fTI were individualized. US could not be performed in 37 patients. The remaining 90 patients (92 fTI) were explored by US ± fine-needle aspiration biopsy (FNAB). US results demonstrated a nodule aspect in 80 cases of which 60 benefited from FNAB. Nineteen of 92 fTI underwent surgery with 10 malignant lesions among the 60 patients performing both US and FNAB.

CONCLUSION

The prevalence of fTI discovered on FDG PET-CT in our population was 1.3% with 10 malignant lesions among the 60 patients performing both US and FNAB.

Coincidence of follicular lymphoma and hurtle cell thyroid carcinoma in a patient at presentation: which one is the source of bone metastasis? Case report and review of the literature

Thyroid incidentaloma is defined as a new identified thyroid lesion occasionally detected during imaging studies. Incidence of thyroid incidentalomas is relatively rare in patients with lymphoma. Because of high rate of malignancy, these lesions with high intensity focal ¹⁸FDG uptake detected on positron emission tomography with computed tomography (PET/CT) should undergo to biopsy regardless of size.

Thyroid incidentalomas on 18FDG-PET/CT: a metabolico-pathological correlation

Background

Thyroid incidentaloma is defined as an unsuspected thyroid lesion found on imaging study or while performing a surgery non-related to the thyroid gland. Most recent scientific literature tends to demonstrate a detection rate of 0.1–4.3% for incidental findings of thyroid focal uptake identified by ¹⁸F-fluorodeoxyglugose Positron Emission Tomography with computed tomography (¹⁸FDG-PET/CT) initially prescribed for nonthyroid disease. From 10.3 to 80.0% of patients who underwent further evaluation are diagnosed with malignant lesions.

Our first objective is to determine the risk of malignancy confined in thyroid incidentalomas(IT) detected on ¹⁸FDG-PET/CT in patients treated in a tertiary care center (Centre Hospitalier Universitaire de Sherbrooke). Second, we want to identify a cut-off value for SUVmax in order to distinguish benign from malignant IT. Third, we look for predictive criterion that can be outlined to help in their management.

Methods

We retrospectively reviewed 40 914 charts of patients who had a ¹⁸FDG-PET/CT done in a tertiary center from 2004 to 2014. For each patient where a thyroid incidentaloma has been identified, Maximum Standardized Uptake Value (SUVmax), ultrasound report, cytology and histopathological results as well as oncologic outcomes were compiled and analyzed.

Results

In this study, the incidence for thyroid incidentaloma detected with ¹⁸FDG-PET/CT is 0.74%. The rate of malignancy present in IT is 8.2% based on histopathological results. Of the patients who underwent surgery, thyroid malignancy was identified in 54.3% of them. Cytoponction showed a strong correlation with final histopathological results (p = 0.009).

Conclusion

Thyroid incidentalomas detected with ¹⁸FDG-PET/CT are relatively infrequent, but the potential risk of malignancy remains elevated. Fine needle aspiration biopsy is the investigation of choice to rule out a malignant incidentaloma when there is no other element in the clinical portrait to preclude such additional work up.

Cytological evaluation by fine needle aspiration biopsy of incidental focal increased fluorodeoxyglucose uptake in thyroid on positron emission tomography scan

BACKGROUND

With the increased use of whole body fluorodeoxyglucose positron emission tomography (PET) scan for staging/restaging or primary diagnosis of neoplasia, thyroid incidentalomas have become more common. The limited reports of PET-positive thyroid incidentalomas showed incidence of malignancy ranging from 14 to 66%, and there is discrepancy in terms of the diagnostic significance of the standard uptake value (SUV) value.

METHODS

This is a retrospective study of 20 PET incidentalomas which had cytological evaluation from October 2009 to February 2015 at a tertiary care university medical center, M:F = 8:12.

RESULTS

Of the 20 cases, 14 (70%) had a cytological diagnosis of atypia or suspicious for neoplasia. Eleven of those (55%) underwent surgical resection with final diagnosis of PTC in 8 cases, follicular carcinoma in one case (5%), follicular adenoma in one case (5%), and Hurthle cell adenoma in one case (5%). There was good correlation between cytological and histological diagnosis. For two cases with cytological diagnosis of suspicious for follicular neoplasm, no further histological diagnosis was obtained. One patient had direct cytological diagnosis of PTC also did not undergo surgical resection/diagnosis due to the advanced primary pancreatic adenocarcinoma. The remaining 6 (30%) cases had a cytological diagnosis of benign follicular nodule. Furthermore, no significant difference between malignant SUV and benign SUV was observed.

CONCLUSIONS

Malignancy was identified in 50% of the PET-positive incidentalomas in our series. PTC constitutes the major malignant diagnosis. No diagnostic value of SUV was observed to differentiate malignant from benign lesions. Diagn. Cytopathol. 2017;45:501-506. © 2017 Wiley Periodicals, Inc.

Recurrence rate in regional lymph nodes in 737 patients with follicular or Hürthle cell neoplasms

BACKGROUND

Preoperative ultrasound (US) evaluation of central and lateral neck compartments is recommended for all patients undergoing a thyroidectomy for malignant or suspicious for malignancy cytologic or molecular findings. Our aim was to find out how frequent was recurrence in regional lymph nodes in patients with follicular or Hürthle cell neoplasm and usefulness of preoperative neck US investigation in patients with neoplasm.

PATIENTS AND METHODS

Altogether 737 patients were surgically treated because of follicular or Hürthle cell neoplasms from 1995 to 2014 at our cancer comprehensive center, among them 207 patients (163 females, 44 males; mean age 52 years) had thyroid carcinoma.

RESULTS

Carcinoma was diagnosed in follicular and Hürthle cell neoplasm in 143/428 and 64/309 of cases, respectively. A recurrence in regional lymph nodes occurred in 12/207 patients (6%) during a median follow-up of 55 months. Among patients with carcinoma a recurrence in regional lymph nodes was diagnosed in follicular and Hürthle cell neoplasms in 2% and 14%, respectively (p = 0.002). Recurrence in regional lymph nodes was diagnosed in 3/428 of all patients with follicular neoplasm and 9/309 of all patients with Hürthle cell neoplasm.

CONCLUSIONS

Recurrence in lymph nodes was diagnosed in 0.7% of patients with a preoperative diagnosis of follicular neoplasm and 3% of patients with a Hürthle cell neoplasm. A recurrence in regional lymph nodes is rare in patients with carcinoma and preoperative diagnosis of follicular neoplasm. Preoperative neck ultrasound examination in patients with a follicular neoplasm is probably not useful, but in patients with Hurtle cell neoplasm it may be useful.