Thyroid microcarcinoma: prevalence, prognosis, and management

Clinical Analysis of BRAFV600E Mutation and Its Correlation With Sonographic Image Characteristics in Papillary Thyroid Carcinoma in Chinese Coastal Areas

This study analyzed the characteristics of BRAF^V600E mutation in papillary thyroid carcinoma (PTC) in Chinese coastal areas. We intended to identify noninvasive methods to determine BRAF^V600E status in thyroid nodules prior to surgery. BRAF^V600E mutation and the sonographic characteristics of thyroid nodules were investigated in 670 PTC patients in our hospital. We aimed to determine the relationship between BRAF^V600E mutation and the clinicopathological and sonographic imaging characteristics of PTC. The mutation rate of the BRAF^V600E was 78.2%. BRAF^V600E mutation was significantly associated with central node (univariate analyses, P = .005; multivariate analyses, P < .001, odds ratio [OR] = 10.255) and lateral node metastases (univariate analyses, P = .001; multivariate analyses, P < .001, OR = 22). It was less frequent in PTC coexisting with Hashimoto's thyroiditis (univariate analyses, P = .016; multivariate analyses, P < .001, OR = .034). Nodules without blood flow had a significantly higher mutation rate of BRAF^V600E in PTC patients (univariate analyses, P = .026). BRAF^V600E mutation was significantly associated with high suspicion in the Thyroid Imaging Reporting and Data System 5 (univariate analyses, P = .004; multivariate analyses, P = .014, OR = 6.456). Our results strongly suggest that BRAF^V600E mutation plays a potential role in lymph node metastasis (central node metastasis, OR = 10.225; lateral node metastasis, OR = 22). Some sonographic imaging features might be helpful in estimating the status of BRAF^V600E preoperatively.

False-Positive Malignant Diagnosis of Nodule Mimicking Lesions by Computer-Aided Thyroid Nodule Analysis in Clinical Ultrasonography Practice

This study aims to test computer-aided diagnosis (CAD) for thyroid nodules in clinical ultrasonography (US) practice with a focus towards identifying thyroid entities associated with CAD system misdiagnoses. Two-hundred patients referred to thyroid US were prospectively enrolled. An experienced radiologist evaluated the thyroid nodules and saved axial images for further offline blinded analysis using a commercially available CAD system. To represent clinical practice, not only true nodules, but mimicking lesions were also included. Fine needle aspiration biopsy (FNAB) was performed according to present guidelines. US features and thyroid entities significantly associated with CAD system misdiagnosis were identified along with the diagnostic accuracy of the radiologist and the CAD system. Diagnostic specificity regarding the radiologist was significantly (p < 0.05) higher than when compared with the CAD system (88.1% vs. 40.5%) while no significant difference was found in the sensitivity (88.6% vs. 80%). Focal inhomogeneities and true nodules in thyroiditis, nodules with coarse calcification and inspissated colloid cystic nodules were significantly (p < 0.05) associated with CAD system misdiagnosis as false-positives. The commercially available CAD system is promising when used to exclude thyroid malignancies, however, it currently may not be able to reduce unnecessary FNABs, mainly due to the false-positive diagnoses of nodule mimicking lesions.

Thyroid follicular microcarcinoma

Differentiated thyroid cancers are the most common malignancies arising in thyroid gland. Papillary thyroid cancer presents a very favorable prognosis, while follicular type is slightly more aggressive, mainly for its attitude to hematogenous spreading with distant metastases. Papillary microcarcinoma (10 mm or less) has an excellent prognosis, largely demonstrated, and its management is changed in the last few years, reducing surgical procedure, role of radio iodine ablation (RAI) and TSH suppression. But no effective data are available for follicular thyroid microcarcinoma (mFTC); very few reports and studies are present in literature about mFTC, mainly for its low incidence. Aim of this paper is to review current literature to reach, in absence of evidence, some suggestion in managing mFTC.

Incidental versus clinical diagnosis of papillary thyroid microcarcinoma. Long-term prognosis

INTRODUCTION

The incidence of papillary thyroid microcarcinoma (PTMC) has increased in recent years, especially in patients operated on for presumably benign thyroid disease. The aim of this study was to analyze the differences between PTMC incidentally diagnosed and PTMC clinically diagnosed, as well as its long-term prognosis.

MATERIAL AND METHODS

The study population consisted of patients with a histological diagnosis of PTMC. Patients with previous thyroid surgery, other synchronous thyroid or extrathyroid malignancies and an ectopic location of PTMC were excluded. Two groups were compared: patients with PTMC incidentally diagnosed (group 1) and patients with PTMC clinically diagnosed (group 2). A multivariate analysis of differentiating factors was performed.

RESULTS

PTMC clinically diagnosed had a high frequency of hypothyroidism (4.6% vs. 18.9%; P=.004), extrathyroidal extension (5.7% vs. 17.6%; P=.018), metastatic lymph nodes (1.1% vs. 18.9%; P<.001) and lymphocytic thyroiditis (5.7% vs. 27%; P<.001). In the multivariate analysis, metastatic lymph nodes (OR: 22.011, IC 95%: 2.621-184.829; P=.004) and lymphocytic thyroiditis (OR: 4.949; IC 95%: 1.602-15.288; P=.005) were associated with the clinical diagnosis of PTMC. During a mean follow-up of 119.8±65.1 months, one recurrence was detected in group 2 (0% vs. 1,4%; P=.460). No patient died due to the disease.

CONCLUSIONS

PTMC clinically diagnosed, although it has more aggressive histopathological characteristics (extrathyroidal extension and metastatic lymph nodes), presents a long-term prognosis similar to the PTMC incidentally diagnosed. The presence of metastatic lymph nodes and lymphocytic thyroiditis were independent factors associated with PTMC clinically diagnosed.

Clinicopathological features of papillary thyroid microcarcinoma with a diameter less than or equal to 5 mm

PURPOSE

This retrospective study was conducted to assess the epidemiological, clinical and histologic characteristics of incidentally identified and presurgically diagnosed papillary thyroid microcarcinomas less than or equal to 5 mm in size (small PTMC).

MATERIALS AND METHODS

Cases from October 2003 to February 2018 were retrieved from pathology databases, and their clinicopathological features were reviewed.

RESULTS

There were a total of 182 cases of small PTMCs, 141 women and 41 men. The mean age at diagnosis was 53.5. Most of the small PTMCs were not detected on clinical examination and workup and were diagnosed incidentally during pathologic examination. 21.4% of small PTMCs showed multifocality, with 21 cases of unilateral multifocal lesions and 18 cases with bilateral multifocal tumors. Small PTMCs were most often follicular variant (51.9%) followed by classic type (47.5%). The average size of follicular variants appeared to be larger than that of the classic type PTMCs (2.84 ± 1.43 mm vs 2.26 ± 1.51 mm, P = 0.01). A total of 66 cases (36.3%) had regional lymph node sampling or selective neck dissection and 15 of these cases identified lymph node metastasis (22.7%). 46.7% of patients with node positive microcarcinomas were male compared with 16% male in group with negative lymph nodes (P = 0.03).

CONCLUSIONS

Small PTMCs (≤5 mm) are often multifocal and bilateral and histology is commonly both the classical and follicular variant of PTC. While often diagnosed incidentally small PTMC can lead to regional lymph node involvement in a significant portion of cases and evaluation of the regional lymph nodes should be considered in the clinical management of these patients.

Ultrasound-guided fine-needle aspiration biopsy of thyroid nodules <10 mm in the maximum diameter: does size matter?

Objective

Ultrasound-guided fine-needle aspiration biopsy (US-FNAB) is a safe and effective method of screening malignant thyroid nodules such as papillary thyroid carcinoma. However, not much data are available regarding the diagnostic efficacy of US-FNAB for papillary thyroid microcarcinoma (≤10 mm in diameter). We aim to compare the diagnostic efficacy of US-FNAB on thyroid nodules between two groups divided by a diameter of 10 mm by correlating the cytological results of US-FNAB with the histopathologic diagnoses in selected patients.

Patients and methods

Eight hundred twenty-two thyroid nodules (Group A: diameter ≤10 mm, n=620; Group B: diameter >10 mm, n=202) from 797 patients treated between March 2014 and June 2017 were retrospectively evaluated. Only nodules with Thyroid Imaging Reporting and Data System (TIRADS) categories 4–6 were enrolled and sampled by US-FNAB, followed by surgical resection.

Results

According to The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) diagnostic categories, 94 thyroid nodules were classified as I, III and IV, and were excluded from the analysis. The resultant 728 thyroid nodules from 721 patients were analyzed. The malignant tendency (TBSRTC V and VI) rates on US-FNAB were 88.2% and 84.6% (P=0.202) in Group A and Group B, respectively, and the malignant rates were 89.5% and 86.9% (P=0.330), respectively, on histopathology. There was a high concordance between cytology and histopathology diagnoses (kappa value =0.797), and no statistical difference in terms of US-FNAB accuracy was found between the two groups (P=0.533).

Conclusion

For thyroid nodules of TIRADS category 4–6, the diagnostic efficacy of US-FNAB is similar for thyroid nodules either smaller or greater than 10 mm in their maximum diameter.

INCIDENTAL THYROID NODULES: RACE/ETHNICITY DISPARITIES AND OUTCOMES

OBJECTIVE

Black patients have a significantly lower incidence of well-differentiated thyroid cancer (WDTC) compared to all other race/ethnic groups, while white patients appear to be at greater risk. This study examines incidental thyroid nodules (ITNs) to assess whether racial disparities in WDTC arise from a differential discovery of ITNs-perhaps due to socioeconomic disparities-or reflect true differences in thyroid cancer rates.

METHODS

A retrospective review was performed of all patients who underwent fine-needle aspiration (FNA) of thyroid nodules by our academic medical center's endocrinology division between January 2006 and December 2010. Medical records were reviewed to identify whether the biopsied thyroid nodule was discovered incidentally through nonthyroid-related imaging or identified by palpation.

RESULTS

FNAs were performed on 1,369 total thyroid nodules in 1,141 study patients; 547 (48%) were classified as white, and 593 (52%) were classified as nonwhite. Among this cohort, 36.6% of patients underwent biopsy for an ITN. White patients were 1.6 times more likely to have undergone a biopsy for a nodule that was incidentally identified compared to nonwhites ( P<.0001). Indicators of socioeconomic status (SES) did not have a significant association with ITNs. Within the ITN cohort, 4.9% of nonwhite patients were found to have a thyroid malignancy compared to 12.9% of white patients ( P<.01).

CONCLUSION

The higher incidence of thyroid cancer in white patients appears to be not only due to diagnostic bias, but also to a true difference in cancer prevalence.

ABBREVIATIONS

FNA = fine-needle aspiration; ITN = incidental thyroid nodule; SEER = Surveillance Epidemiology and End Results; SES = socioeconomic status; WDTC = well-differentiated thyroid cancer.

Incidence and histological patterns of thyroid cancer in Sri Lanka 2001-2010: an analysis of national cancer registry data

BACKGROUND

An increasing incidence of thyroid cancer is observed in many developed countries. Increasing incidence may also reflect better reporting or increased diagnostic scrutiny. We conducted this study to examine trends in thyroid cancer incidence and histological patterns in Sri Lanka.

METHODS

A retrospective cohort evaluation of patients with thyroid cancer during 2001-2010 was performed using population based data published from the Sri Lanka National Cancer Registry. Trends in incidence and histological patterns were analysed by age and gender.

RESULTS

The age-standardized incidence of thyroid cancer increased from 2.44 per 100,000 in 2001 (95% confidence interval [95% CI]: 2.21-2.67) to 5.16 per 100,000 in 2010 (95% CI: 4.85-5.47); a 2.1-fold increase (p < 0.05 for trend). A greater part of this increase is attributable to increase in incidence of papillary thyroid cancer, which increased from 1.64 to 3.61 per 100,000; a 2.2-fold increase (p < 0.05 for trend). Follicular cancer showed lesser, yet a significant increase from 0.56 to 0.95 per 100,000 (p < 0.05). Other varieties of thyroid cancer showed no significant increases in incidence. Trends in the increases in incidence of papillary cancer in females showed a much greater increase compared with males (from 2.45 to 5.60 per 100,000, a 2.28-fold increase in females compared with from 0.82 to 1.55; a 1.89-fold increase in males, p < 0.001). Highest incidence of papillary cancer was observed in 30-39-year age group, which has increased from 5.56 to 12.9 per 100,000; a 2.32-fold increase (p < 0.001).

CONCLUSIONS

The increasing incidence of thyroid cancer in Sri Lanka is predominantly due to the increasing incidence of papillary cancers. These trends may reflect increased detection and better reporting, although an inherent increase in the incidence is the likely main contributor. Further studies including tumour stage and mortality may help answer these questions.

'Incidental' and 'non-incidental' thyroid papillary microcarcinomas are two different entities

OBJECTIVE

Papillary thyroid microcarcinomas (microPTC) may be 'incidental' (Inc-microPTC), occasionally found at histology after surgery for benign disease or 'non-incidental' (Non-Inc-microPTC), diagnosed on clinical grounds. It is unclear whether these different microPTC reflect the same disease. The aim of the study was to compare Inc-microPTC and Non-Inc-microPTC for clinical and histological features as well as for serum TSH, a known factor involved in PTC development.

DESIGN

We evaluated histology and serum TSH levels of consecutive patients submitted to thyroidectomy for goiter with compressive symptoms or for cytological diagnosis suspicious/indicative of PTC.

METHODS

In total, 665 consecutive patients (259 with a single thyroid nodule, SN and 406 with a multinodular gland, MN) were included in the study. According to histology, patients were classified as: benign nodular goiter (Benign, n=291); Inc-microPTC (n=92); Non-Inc-microPTC (n=67) and PTC≥1cm (macroPTC, n=215).

RESULTS

Inc-microPTC were significantly more frequent in MN than in SN (66/406, 16.2% vs 26/259, 10.0%, P=0.02). Patients with Inc-microPTC compared with Non-Inc-microPTC were older (mean age±s.d. 53.3±13.2 years vs 44.9±14.8 years, P=0.0002), had a smaller tumor size (median 4mm vs 9mm, P<0.0001), a higher frequency of multifocality (70/92, 76.1% vs 35/67, 52.2% P=0.001) and lower levels of TSH (median 0.6mIU/L, IR: 0.4-1.0mIU/L vs value 1. mIU/L, IR: 0.6-1.4mIU/L vs P=0.0001).

CONCLUSION

Incidental and non-incidental papillary thyroid microcarcinomas appear to be two different entities.

Trends in thyroid cancer incidence in Texas from 1995 to 2008 by socioeconomic status and race/ethnicity

BACKGROUND

Thyroid cancer incidence is increasing, potentially due to enhanced diagnostic practices. However, access to healthcare may be dependent on socioeconomic status (SES) and race/ethnicity. Consequently, certain segments of the population may experience thyroid cancer overdiagnosis as a result of greater access to and use of enhanced diagnostic technology. The current study examined trends by SES in thyroid cancer incidence at the census tract level from 1995 to 2008 for the population of Texas, as well as by racial/ethnic subgroup.

METHODS

Joinpoint regressions were used to examine incidence trends over time by SES for the study population, and for the non-Hispanic white, non-Hispanic black, and Hispanic subgroups separately. Other race/ethnicities were not adequately represented for subgroup analyses.

RESULTS

There were 22,390 incident thyroid cancer cases (65.0% white, 6.7% black, 24.3% Hispanic, 4.1% Asian/other races; 85.9% papillary histology). The low SES group experienced a steady increase in incidence since 1995 (6.7% per year, p<0.05), whereas incidence among the high SES group has increased at a rate of 8.6% per year since 1999 (p<0.05). The joinpoint projected incidence trends for the low and high SES groups were significantly different (p=0.047). Whites experienced a steady increase in incidence over time among both high and low SES groups (7.6% per year p<0.05), whereas blacks and Hispanics of higher SES had a much more pronounced increase in incidence over time relative to their lower SES counterparts (blacks=12.8% vs. 4.1%; Hispanics=11.2% vs. 8.3%, p<0.05). For blacks and Hispanics, joinpoint projected incidence trends for the low and high SES groups were significantly different from one another (p<0.001-0.004).

CONCLUSIONS

These results identify groups experiencing the greatest problem of increasing thyroid cancer incidence, and raise concern that greater access to healthcare may be accompanied by thyroid cancer overdiagnosis. A dual focus on delineating and preventing disease-related causal factors and focusing clinical attention on avoiding overdiagnosis among certain populations (e.g., high SES) may be advisable to address thyroid cancer in Texas. Clinicians are encouraged to adhere to ATA/NCCN guidelines when choosing patients for thyroid ultrasound, selecting which nodules to examine, and deciding which patients should proceed to biopsy.

Surgical management of thyroid cancer

Thyroid cancer is the most common endocrine neoplasm; however, it only accounts for less than 1% of all human malignances. Thyroid cancers are divided into well differentiated and non-well differentiated cancers, according to their histology and behavior. The surgical management options of well-differentiated thyroid cancer include total or near-total thyroidectomy, subtotal thyroidectomy and lobectomy plus isthmusectomy. The extent of surgery for thyroid cancer continues to be an area of controversy. Complications associated with thyroid surgery are directly proportional to the extent of thyroidectomy and inversely proportional to the experience of the operating surgeon. They occur less frequently with good surgical technique and better understanding of surgical anatomy, and include wound healing and infections (seroma, hematoma and wound infection), nerve injury, hypoparathyroidism, hypothyroidism, postoperative hemorrhage and respiratory obstruction.

Pathologic diagnosis of papillary thyroid carcinoma: today and tomorrow

Papillary thyroid carcinoma is the most common malignancy of the thyroid. It is a well-differentiated tumor and the majority behaves in an indolent fashion. The pathologic diagnosis of papillary carcinoma in both cytology and histologic specimens is based upon demonstration of typical nuclear morphology. Using these morphologic criteria, most papillary cancers can be diagnosed with ease, except cases in which there is a paucity of diagnostic nuclear features. Despite advances in the treatment of thyroid cancer, disease recurrences and metastasis can be observed in 20% of cases. Recently, many advances have been made in the pathogenesis of papillary thyroid carcinoma. The notable genetic events include Ret/PTC rearrangements, Ras and BRAF gene mutations. The identification of these has also led to their use in diagnosis and predicting prognosis of papillary thyroid carcinoma. In addition, these involved genes may also serve as targets for cancer chemotherapy in patients where standard thyroid cancer treatment is not effective.

Impact of enhanced detection on the increase in thyroid cancer incidence in the United States: review of incidence trends by socioeconomic status within the surveillance, epidemiology, and end results registry, 1980-2008

BACKGROUND

In the past 3 decades, the incidence of thyroid cancer in the United States has been increasing. There has been debate on whether the increase is real or an artifact of improved diagnostic scrutiny. Our hypothesis is that both improved detection and a real increase have contributed to the increase.

METHODS

Because socioeconomic status (SES) may be a surrogate for access to diagnostic technology, we compared thyroid cancer incidence trends between high- and low-SES counties within the Surveillance, Epidemiology, and End Results 9 (SEER 9) registries. The incidence trends were assessed using joinpoint regression analysis.

RESULTS

In high-SES counties, thyroid cancer incidence increased moderately (annual percentage change 1 [APC1]=2.5, p<0.05) before the late 1990s and more pronounced (APC2=6.3, p<0.05) after the late 1990s. In low-SES counties, incidence increased steadily with an APC of 3.5 (p<0.05) during the entire study period (1980-2008). For tumors ≤4.0 cm, incidence was higher in high-SES counties, and APC was higher for high- than low-SES counties after the late 1990s. For tumors >4.0 cm, high- and low-SES counties had similar increasing incidence trends. Similarly, for tumors ≤2.0 cm, the incidence trends differed between counties that are in or adjacent to metropolitan areas and counties that are in rural areas, whereas for tumors >2.0 cm, all counties regardless of area of residence had similar increasing trends.

CONCLUSIONS

Enhanced detection likely contributed to the increased thyroid cancer incidence in the past decades, but cannot fully explain the increase, suggesting that a true increase exists. Efforts should be made to identify the cause of this true increase.

Factors influencing the outcome of patients with incidental papillary thyroid microcarcinoma

Objective. To analyze some factors that could influence the outcome of patients with PTMC. Material and Methods. This is a longitudinal observational study. All patients diagnosed and treated for papillary thyroid microcarcinoma at the University Hospital of Vigo, between January 1994 and December 2003, were included in the present study. Demographic characteristics, tumour characteristics, TNM stage, rate of recurrence, and treatment with ¹³¹I were the study variables. Results. Ninety-one patients (75 females) with an average age of 47.7 ± 13.4 years, range 19–81, were studied. Initial tumour staging was T1 in 90 patients and T4a in 1 case. Initial lymph node involvement was present in 4 cases (4.4%). We only found one case with distant metastases at diagnosis. Postsurgical evaluation of thyroid specimens revealed that 28 (30.7%) tumours were multifocal. The average size of the tumour was 0.44 ± 0.25 cm, range 0.1–1. Univariate analysis reveals a statistically significant association between tumour multifocality and postsurgical ¹³¹I therapy with the recurrence rate. In the multivariate analysis only multifocality (P = 0.037, HR 5.7) was a significant risk factor for the recurrence rate. Conclusions. Our results indicate that tumour multifocality is an independent predictor of relapse but neither the tumour size nor postsurgical ¹³¹I therapy.

Thyroid microcarcinoma

Nowadays the most commonly occurring differentiated thyroid cancer in many countries is a microcarcinoma in patients older than 45 years, incidentally found during neck ultrasound. In view of their low morbidity and mortality, the crucial point is how to manage such microcarcinomas. Recently published European and American guidelines aim to minimize the diagnostic and therapeutic procedures without affecting the diagnostic accuracy and the therapeutic effectiveness, keeping in mind that we are dealing with patients who have a normal life expectancy and to whom we have to guarantee an excellent quality of life. The present review will summarize the clinical and pathological features of thyroid microcarcinoma, including its definition, prevalence, presentation, pathology, genetic, clinical impact and will try to derive from them a rationale for therapeutic and diagnostic intervention.

Thyroid microcarcinoma

Nowadays the most commonly occurring differentiated thyroid cancer in many countries is a microcarcinoma in patients older than 45 years, incidentally found during neck ultrasound. In view of their low morbidity and mortality, the crucial point is how to manage such microcarcinomas. Recently published European and American guidelines aim to minimize the diagnostic and therapeutic procedures without affecting the diagnostic accuracy and the therapeutic effectiveness, keeping in mind that we are dealing with patients who have a normal life expectancy and to whom we have to guarantee an excellent quality of life. The present review will summarize the clinical and pathological features of thyroid microcarcinoma, including its definition, prevalence, presentation, pathology, genetic, clinical impact and will try to derive from them a rationale for therapeutic and diagnostic intervention.

Clinical outcome, role of BRAF(V600E), and molecular pathways in papillary thyroid microcarcinoma: is it an indolent cancer or an early stage of papillary thyroid cancer?

Most human thyroid cancers are differentiated papillary carcinomas (PTC). Papillary thyroid microcarcinomas (PTMC) are tumors that measure 1 cm or less. This class of small tumors has proven to be a very common clinical entity in endocrine diseases. PTMC may be present in 30-40% of human autopsies and is often identified incidentally in a thyroid removed for benign clinical nodules. Although PTMC usually has an excellent long-term prognosis, it can metastasize to neck lymph nodes; however deaths related to this type of thyroid tumor are very rare. Few data exist on molecular pathways that play a role in PTMC development; however, two molecules have been shown to be associated with aggressive PTMC. S100A4 (calcium-binding protein), which plays a role in angiogenesis, extracellular matrix remodeling, and tumor microenvironment, is over-expressed in metastatic PTMC. In addition, the BRAF(V600E) mutation, the most common genetic alteration in PTC, is present in many PTMC with extra thyroidal extension and lymph node metastasis. Importantly, recently developed selective [e.g., PLX4720, PLX4032 (Vemurafenib, also called RG7204)] or non-selective (e.g., Sorafenib) inhibitors of BRAF(V600E) may be an effective treatment for patients with BRAF(V600E)-expressing PTMCs with aggressive clinical-pathologic features. Here, we summarize the clinical outcome, cancer genetics, and molecular mechanisms of PTMC.

Managing thyroid microcarcinomas

Papillary thyroid microcarcinomas (PTMCs) are the most common form of classic papillary thyroid carcinoma (PTC). PTMCs are typically discovered by fine-needle- aspiration biopsy (FNAB), usually with sensitive imaging studies, or are found during thyroid surgery in a patient without a previously known history of thyroid carcinoma. However, the definition of PTMC has not always been universally accepted, thus creating controversy concerning the diagnosis and treatment of PTMC. The aim of this review is to summarize the clinical features of PTMC and identify the widely differing opinions concerning the diagnosis and management of these small ubiquitous thyroid tumors.

Clinical features and therapeutic implication of papillary thyroid microcarcinoma

Papillary thyroid microcarcinomas (PTMs) are small tumors (< or =1 cm of diameter) that belong to the well-differentiated low-risk carcinomas of the thyroid, which are characterized by benign behavior, probably of little clinical significance, and do not affect patients' survival. They are found in otherwise normal thyroids or in multinodular goiters with a clinical frequency varying substantially according to different series. Sometimes, PTM may be associated with lymph node metastases at presentation and/or locoregional recurrences during follow-up. Distant metastases are extremely rare, but have been reported. Although deaths related to PTM are almost unknown, PTM raises therapeutic implications. This review addresses the issue of definition, treatment, and follow-up of PTM.

Incidentally discovered tumors of the endocrine glands

Clinically inapparent masses, or ‘incidentalomas’ of the endocrine glands are increasingly common owing to continued advancements in medical imaging. Incidentalomas of the adrenal glandS have received substantial attention in the literature, whereas lesions of the thyroid and endocrine pancreas, though frequently encountered in the clinic, have received relatively little attention. We review the detection and subsequent management of incidentalomas of the thyroid, adrenal and pancreas, with specific attention paid to the mode of detection and risk stratification of lesions.

Ectopic intrathyroidal nonfunctioning parathyroid cyst

OBJECTIVE

To describe a rare case of ectopic intrathyroidal parathyroid cyst (PC) in a 29-year-old woman who had been referred to us because of a multinodular goiter.

METHODS

We review the clinical, laboratory, and radiographic findings as well as the treatment in our patient and provide a brief discussion of the associated literature.

RESULTS

Ultrasonography of the neck showed the presence of 2 thyroid nodules in the left lobe, the larger of which was solid and the smaller of which had a cystic appearance. A small nodular area was also found in the right thyroid lobe (diameter, less than 8 mm). A thyroid scan performed with technetium showed the absence of uptake by both left lobe nodules. Fine-needle aspiration biopsy (FNAB) of the 2 major nodular lesions revealed that the larger thyroid nodule was benign and the smaller was a cyst with clear fluid. Measurement of parathyroid hormone in the FNAB fluid showed a high concentration, suggestive of the diagnosis of PC. Normal serum levels of parathyroid hormone and calcium indicated that it was a nonfunctioning intrathyroidal PC. The PC disappeared after FNAB, but the lesion recurred 3 months later. Therefore, the patient underwent near-total thyroidectomy. Histologic examination confirmed the diagnosis of intrathyroidal PC, and a papillary microcarcinoma (6 mm in diameter) was found in the right lobe of the thyroid.

CONCLUSION

Although an ectopic intrathyroidal PC is rare, the frequency of occult papillary microcarcinoma of the thyroid is high. The association we describe, however, should be considered incidental. To our knowledge, this is the first report of an association of an intrathyroidal PC with papillary microcarcinoma of the thyroid.

Microcarcinoma of the thyroid

Thyroid microcarcinoma, defined as a thyroid tumor measuring 1 cm or less, is an extremely indolent tumor. Papillary microcarcinoma, the most common subtype, is often identified incidentally in a thyroid removed for benign clinical nodules or diffuse processes (eg, thyroiditis). In this clinical situation, over 99% are cured by simple lobectomy. In the less common scenario, the microcarcinoma is the primary lesion to a lymph node metastasis presenting clinically as a neck mass; in this situation, the tumor should be treated as a clinical cancer. Other rare microcarcinomas can occur and, of these, the most recently described is micromedullary carcinoma. In the familial setting, these lesions are identified in prophylactic thyroidectomies and are not unexpected findings. However, when found as sporadic tumors, their implications are still unknown. The histologic features, pathologic mimics, and molecular facets of these microscopic neoplasms are discussed in this review.

Thyroid microcarcinoma: fine-needle aspiration diagnosis and histologic follow-up

The increased sensitivity of many imaging modalities (ultrasound, computed tomography scan, magnetic resonance imaging) has resulted in the identification of thyroid nodules, measuring 1 cm or less. Usually these small lesions are regarded as incidental and are not sampled by fine-needle aspiration (FNA). However, some of these lesions undergo FNA because of suspicious radiology findings (multifocality, calcification, etc) or in patients with a history of radiation to the head and neck region. We present FNA findings and histologic follow-up of 39 thyroid nodules that measured 1.0 cm or less. All FNAs were performed under ultrasound guidance. The lesions ranged in size from 0.2 to 1.0 cm. Twenty-two lesions were diagnosed as papillary carcinoma (PTC), 4 as medullary carcinoma (MC), and 13 as suspicious for PTC on FNA. Histologic follow-up showed PTC in 35 and MC in 4 cases; 11 PTC were multifocal (31%) and lymph node metastases were present in 8 (16%) cases. Ultrasound-guided FNA is effective in the sampling of thyroid cancers that are 1.0 cm or less. The present study shows that some of these lesions can be clinically significant.

Follicular-patterned lesions of the thyroid: the bane of the pathologist

This review focuses on follicular-patterned lesions of the thyroid gland and their differential diagnosis. Included are a discussion of the features differentiating follicular adenoma from adenomatous or hyperplastic nodule and follicular adenoma from follicular carcinoma and the follicular variant of papillary thyroid carcinoma. The cytologic and histologic characteristics are described, and criteria for diagnosing the major follicular lesions are reviewed.

Prognostic factors in well-differentiated follicular-derived carcinoma and medullary thyroid carcinoma

This paper reviews both clinicopathologic and biological factors in differentiated thyroid carcinoma of follicular and C-cell derivation. The value of specific histological parameters including tumor subtypes, vascular invasion as predictors of prognosis in these tumors is discussed and the pertinent literature reviewed. The utility of ploidy analysis and immunohistochemical assessment of hormonal and tumor markers are described. Current information on biological and molecular markers that may be helpful in predicting behavior is discussed. The commonly used staging systems for thyroid cancer are briefly described.