Papillary thyroid carcinoma in Kanazawa, Japan: prognostic significance of histological subtypes

Prognostic factors for recurrence in patients with papillary thyroid carcinoma

BACKGROUND

The prognostic factors for tumor recurrence and mortality of patients diagnosed with Papillary Thyroid Carcinoma (PTC) with immediate surgery in Colombia has not been reported.

OBJECTIVE

To retrospectively evaluate the risk factors for recurrence and survival at 10 years in patients with the diagnosis of PTC treated at Fundación Santa Fe deBogota (FSFB).

METHODS

A total of 486 patients with thyroid surgery accompanied by medical follow-up were recruited. Demographic, clinical, and pathological variables were followed-up for a median period of 10 years.

RESULTS

The most significant variables for recurrence were tumors with > 4 cm of size (hazard ratio [HR] = 8.1; 95% confidence interval [CI] = 1.7-55) and extrathyroidal spread (HR = 26.7; 95% CI = 3.1-228).

CONCLUSION

PTC in our population has low rates of mortality (0.6%) and recurrence (9.6%), with an average time of recurrence of 3 years. Size of the lesion, positive surgical margins, extrathyroidal spread, and high postoperative serum thyroglobulin (Tg) level act as prognostic factors that determine the likelihood of recurrence. Unlike other studies, the influence of age and gender does not act as a prognostic factor.

Clinical significance of papillary thyroid carcinoma with solid/trabecular growth

OBJECTIVE

The clinical relevance of solid/trabecular (ST) growth in papillary thyroid carcinoma (PTC) is unclear. In this study, we investigated the impact of any amount of ST growth on tumour characteristics and patient outcomes. Furthermore, we evaluated whether ST growth per se affected patients' prognosis in the absence of aggressive features, namely vascular invasion.

DESIGN

We analysed 222 PTC patients followed up for more than 5 years in the Department of Endocrinology of the Instituto Português de Oncologia de Lisboa Francisco Gentil from 2002 to 2020. All PTC cases with any percentage of ST growth were included and compared with PTC without ST growth (1:2). Carcinomas with high-grade features were excluded.

RESULTS

There were 74 PTC cases with ST growth and 148 without ST growth (median follow-up of 9.3 years). PTC-ST was associated with larger tumour size (p = 0.001) and increased frequency of vascular invasion (p < 0.001) compared with PTC. However, PTC-ST did not exhibit a higher incidence of extrathyroidal extension (p = 1.000) or lymph node metastasis (p = 0.433). Despite the significantly higher prevalence of distant metastasis in PTC-ST compared with PTC (p = 0.043), the significance is lost when the cases with vascular invasion were excluded (p = 0.347). The total radioiodine activity was higher in PTC-ST than in PTC (p = 0.008). Recurrence rates were similar between groups (p = 0.755). The 10-year overall survival and disease-free survival rates for PTC-ST were 94.6% and 98.6%, respectively, similar to the PCT without ST growth (p = 0.097 and p = 0.333, respectively). There was no evidence of an association between the presence of an ST component (p = 0.201) with the risk of death or recurrence, whereas the presence of distant metastasis significantly increased the risk of these events (hazard ratio 10.14, p < 0.001).

CONCLUSIONS

The presence of ST growth was associated with several aggressive clinicopathological features. However, the risk of cancer recurrence and death for PTC-ST were similar to PTC. In the absence of vascular invasion, the clinical impact of ST growth alone is negligible.

Redefining the Solid Variant of Papillary Thyroid Carcinoma: A Multi-institutional Retrospective Study

AIMS

The definition of papillary thyroid carcinoma, solid variant (PTC-SV) varies from >50% to 100% of solid/trabecular/insular growth (STI). We aimed to identify prognostic factors and to establish an appropriate STI cutoff for PTC-SV in this multi-institutional study of 156 PTCs with STI.

RESULTS

Nodal metastases were seen in 18% and were associated with higher percentage of papillary and STI. When substratified by infiltration/encapsulation status, STI percentage did not impact risk of nodal metastasis. pN1 stage was seen in 51% of infiltrative tumors and 1% of encapsulated lesions. Overall, PTC with STI had an excellent prognosis. The 10-year DFS was 87% in the entire cohort, 94% in encapsulated lesions, and 76% in infiltrative tumors. STI percentage did not impact DFS. Fifty-four patients had noninvasive encapsulated lesions with 2% to 100% STI. None developed recurrence. Encapsulated lesions were enriched with RAS mutations (54%), whereas infiltrative lesions lacked RAS mutations (4%). BRAF V600E mutation was an infrequent event, being seen in 11% of the entire cohort.

CONCLUSION

In PTC with STI, the determining factor for nodal metastasis and DFS is the encapsulation/infiltration status rather than STI percentage. Encapsulated noninvasive tumors with STI follow an indolent course with a very low risk of nodal metastasis and recurrence. Overall, PTC with STI has an excellent prognosis with a 10-year DSS and DFS of 96% and 87% respectively. Therefore, the classification of SV-PTC as an aggressive PTC subtype may be reconsidered.

Prognostic indicators for papillary thyroid carcinoma

Differentiated thyroid cancer (DTC) includes more than 90% of all thyroid carcinoma and its incidence is growing, mainly due to an increase in the incidence of papillary thyroid cancer (PTC) for the widespread use of neck ultrasonography. Areas covered: Several prognostic factors should be considered during the management of PTC in order to provide the most effective treatment. The most important prognostic factors in PTC include personal and pathological features such as patient's age, gender, hystotype, tumor size, extrathyroidal extension, lymph node involvement, presence of local or distant metastases and molecular analyses. We performed a search in the PubMed database for studies published in English since 1960 using the terms: 'thyroid cancer', 'prognostic factors', 'age', 'gender', 'hystotype', 'tumor size', 'extrathyroidal extension', 'lymph node', 'metastases' and 'molecular analyses'. Expert commentary: Prognostic factors can guide clinicians during the treatment and follow-up of DTC patients, but it is now evident that the risk of recurrence or death must be evaluated periodically, on the basis of individual risk, according to the response to initial therapy or the subsequent therapy required during follow-up.

2015 American Thyroid Association Management Guidelines for Adult Patients with Thyroid Nodules and Differentiated Thyroid Cancer: The American Thyroid Association Guidelines Task Force on Thyroid Nodules and Differentiated Thyroid Cancer

BACKGROUND

Thyroid nodules are a common clinical problem, and differentiated thyroid cancer is becoming increasingly prevalent. Since the American Thyroid Association's (ATA's) guidelines for the management of these disorders were revised in 2009, significant scientific advances have occurred in the field. The aim of these guidelines is to inform clinicians, patients, researchers, and health policy makers on published evidence relating to the diagnosis and management of thyroid nodules and differentiated thyroid cancer.

METHODS

The specific clinical questions addressed in these guidelines were based on prior versions of the guidelines, stakeholder input, and input of task force members. Task force panel members were educated on knowledge synthesis methods, including electronic database searching, review and selection of relevant citations, and critical appraisal of selected studies. Published English language articles on adults were eligible for inclusion. The American College of Physicians Guideline Grading System was used for critical appraisal of evidence and grading strength of recommendations for therapeutic interventions. We developed a similarly formatted system to appraise the quality of such studies and resultant recommendations. The guideline panel had complete editorial independence from the ATA. Competing interests of guideline task force members were regularly updated, managed, and communicated to the ATA and task force members.

RESULTS

The revised guidelines for the management of thyroid nodules include recommendations regarding initial evaluation, clinical and ultrasound criteria for fine-needle aspiration biopsy, interpretation of fine-needle aspiration biopsy results, use of molecular markers, and management of benign thyroid nodules. Recommendations regarding the initial management of thyroid cancer include those relating to screening for thyroid cancer, staging and risk assessment, surgical management, radioiodine remnant ablation and therapy, and thyrotropin suppression therapy using levothyroxine. Recommendations related to long-term management of differentiated thyroid cancer include those related to surveillance for recurrent disease using imaging and serum thyroglobulin, thyroid hormone therapy, management of recurrent and metastatic disease, consideration for clinical trials and targeted therapy, as well as directions for future research.

CONCLUSIONS

We have developed evidence-based recommendations to inform clinical decision-making in the management of thyroid nodules and differentiated thyroid cancer. They represent, in our opinion, contemporary optimal care for patients with these disorders.

Expression patterns of glucose transporter-1 gene and thyroid specific genes in human papillary thyroid carcinoma

PURPOSE

The expression of glucose transporter-1 (Glut-1) gene and those of major thyroid-specific genes were examined in papillary carcinoma tissues, and the expressions of these genes were compared with cancer differentiation grades.

MATERIALS AND METHODS

Twenty-four human papillary carcinoma tissues were included in this study. The expressions of Glut-1- and thyroid-specific genes [sodium/iodide symporter (NIS), thyroid peroxidase, thyroglobulin, TSH receptor and pendrin] were analyzed by RT-PCR. Expression levels were expressed as ratios versus the expression of beta-actin. Pathologic differentiation of papillary carcinoma was classified into a relatively well-differentiated group (n = 13) and relatively less differentiated group (n = 11).

RESULTS

Glut-1 gene expression was significantly higher in the less differentiated group (0.66 ± 0.04) than in the well-differentiated group (0.59 ± 0.07). The expression levels of the NIS, PD and TG genes were significantly higher in the well-differentiated group (NIS: 0.67 ± 0.20, PD: 0.65 ± 0.21, TG: 0.74 ± 0.16) than in the less differentiated group (NIS: 0.36 ± 0.05, PD: 0.49 ± 0.08, TG: 0.60 ± 0.11), respectively. A significant negative correlation was found between Glut-1 and NIS expression, and positive correlations were found between NIS and TG, and between NIS and PD.

CONCLUSION

The NIS, PD and TG genes were highly expressed in well-differentiated thyroid carcinomas, whereas the Glut-1 gene was highly expressed in less differentiated thyroid carcinomas. These findings provide a molecular rationale for the management of papillary carcinoma, especially in the selection of FDG PET or radioiodine whole-body scan and I-131-based therapy.

A preoperative nomogram for the prediction of ipsilateral central compartment lymph node metastases in papillary thyroid cancer

BACKGROUND

Central compartment lymph node metastases in papillary thyroid carcinoma (PTC) are difficult to detect preoperatively, and the role of routine or prophylactic central compartment lymph node dissection (CLND) in managing PTC remains controversial. The aim of this project was to create a nomogram able to predict the occurrence of central compartment lymph node metastasis using readily available preoperative clinical characteristics.

METHODS

Records from patients undergoing total thyroidectomy and lymph node dissection for PTC in the period 1968-2012 were analyzed. Nodal status was based on results of serial hematoxylin and eosin (H&E) examination. Age, sex, tumor size, tumor site, and multifocality were included in a multivariable logistic regression model to predict lymph node metastasis. A coefficient-based nomogram was developed and validated using an external patient cohort.

RESULTS

The study population included 914 patients (80% females) with an average central compartment nodal yield of eight per patient. Central compartment lymph node metastases were present in 390 patients (42.7%). The variables with the strongest predictive value were age (p<0.001), male sex (p<0.001), increasing tumor size (p<0.001), and tumor multifocality (p<0.05). The nomogram had good discrimination with a concordance index of 76.4% [95% confidence interval 73.3-79.4], supported by an external validation point estimate of 61.5% [95% confidence interval 49.5-73.6]. An online calculator and smartphone application were developed for point of care use.

CONCLUSIONS

A validated nomogram utilizing readily available preoperative variables has been developed to give a predicted probability of central lymph node metastases in patients presenting with PTC. This nomogram may help guide surgical decision making in PTC.

Surgery of lymph nodes in papillary thyroid cancer

Optimal treatment for differentiated thyroid carcinoma is controversial with respect to the extent of thyroid resection, the extent and technique of nodal dissection and use of prophylactic radioiodine treatment. Postoperative complications, such as recurrent laryngeal nerve injury and definitive hypoparathyroidism, have carried great weight in the discussion regarding how radical the surgical treatment should be. The discussion of whether total thyroidectomy or lesser procedures should be the treatment for thyroid carcinomas has been protracted. Now, reasonable agreement exists that total thyroidectomy is the best treatment and the focus of the discussion has moved to the treatment of lymph nodes. At the time of diagnosis, node metastases are a common finding in patients with differentiated thyroid cancer, in particular papillary carcinoma. The argument supporting a radical approach to lymph node excision is that the presence of node metastases increases the recurrence rate. Advocates for the conservative approach believe that little association exists between node metastases and death from thyroid carcinoma. This paper reviews relevant medical literature published in the English language on surgery of lymph nodes in differentiated thyroid cancer with well-controlled trials. Searches were last updated in June 2006.

Aggressive variants of papillary thyroid carcinoma

A number of histologic variants of well-differentiated papillary carcinoma have been found to be associated with more aggressive tumor behavior. Tall cell, columnar cell, diffuse sclerosing, solid/trabecular, and insular variants of well-differentiated papillary thyroid cancer are all potentially more aggressive than conventional papillary thyroid cancer. When subjected to multivariate analysis, however, evidence that the histologic subtype of tumor is an independent predictor of outcome is weak. Rather, the aggressive variants tend to present with features recognized by other staging systems as associated with a worse prognosis, including higher histologic grade, extracapsular spread, large tumor size, and the presence of distant metastases. Prognosis is directly related to the presence of these features. The state of our knowledge is limited by the relatively small number of cases that have been studied. The presence of an aggressive variant of papillary carcinoma should alert the surgeon that he is dealing with a potentially aggressive tumor. Clinical treatment decisions should be based on the stage of the disease, influenced by the knowledge that the aggressive variants tend to be associated with higher risk factors. The surgeon must be prepared to perform at the first, or second stage, a total thyroidectomy, central compartment neck dissection, additional lymphadenectomy, and/or resection of invaded surrounding structures, and search for distant metastasis. Postoperative radioactive iodine should generally be administered for these variants as they will generally be intermediate to advanced tumors. The tall cell variant is often refractory to such treatment but may be susceptible to treatment targeted against BRAF mutation. External beam irradiation may be used in cases of incomplete resection.

Diffuse sclerosing variant of papillary carcinoma of the thyroid: imaging and cytologic findings

Diffuse sclerosing variant of papillary thyroid carcinoma (DSPC) is a rare variant of papillary thyroid carcinoma, for which the imaging and cytologic features have not been reported. The aim of this study is to gain better insight into the characteristic imaging and cytologic features of DSPC and to suggest treatment guidelines. We retrospectively analyzed the ultrasonographic and computed tomographic (CT) features in eight patients diagnosed with pathologically proven DSPC between 1996 and 2006. Of these eight patients, five patients underwent preoperative ultrasonography (US)-guided fine-needle aspiration (FNA). All the patients were women, who presented at a relatively young age (mean age: 31.9 years) with large tumors (mean diameter: 5.9 cm) and cervical lymph node metastases. The US features (7/8) of DSPC were heterogeneous echotexture (7/7), solid composition (7/7), ill-defined margins (4/7), scattered microcalcifications having snowstorm appearance (7/7), and various echogenicities. CT findings (6/8) revealed numerous microcalcifications and multiple enlarged nodes in all the patients. Cytological examination showed lymphocytes intermingled with nests of tumor cells, psammoma bodies, and squamous differentiation with typical nuclear features of papillary carcinoma in all. Through the combination of typical imaging findings and careful cytological examination, DSPC can be diagnosed preoperatively, allowing for the aggressive surgical treatment required in treating this disease.

Prevalence and prognostic significance of tall cell variant of papillary thyroid carcinoma

The aim of this study was to assess the prevalence, prognostic factors, and long-term outcome of tall cell variant (TCV) in comparison with the conventional forms of papillary thyroid carcinoma (PTC). A total of 945 patients with thyroid cancer were treated and followed up from 1960 to 1998. Pathologic review was performed in 778 patients (84%) of the cohort. Of these, 674 had PTC: 503 (74%) had conventional form (CF); 56 (8%), TCV; and 155 (17%), other variants of PTC. Tall cell variant was associated with tumors of larger size (P < .001), bilaterality (P < .02), multifocality (P < .04), and extrathyroidal invasion (P < .001). Treatment was similar in both groups, but neck dissection was performed more frequently in patients with TCV (P < .04). The 10-year overall and event-free survival rates were, respectively, 90% and 85% in the CF versus 79% and 67% in the TCV group (P < .001). Histologic subtype did not have an effect on clinical outcome after multivariate analysis, the most relevant factors being age, involved nodes, or the "Metastasis, Age, Completeness, Invasion, Size" classification after multivariate analysis. In this large cohort of patients, TCV represents 8.3% of PTC, and it is a more aggressive form of PTC than CF because of the higher stage and increased grade.

Prognostic Importance of Sclerosing Variant in Papillary Thyroid Carcinoma

The diffuse sclerosing variant (DSV) of papillary thyroid carcinoma is known for its high aggressiveness, high incidence of lymph node metastases, and high incidence of pulmonary metastases, and thus its consequently poorer prognosis. In this study, we undertook a retrospective analysis of papillary thyroid carcinomas to assess whether DSV can be considered a predictive factor for prognosis. We performed a retrospective evaluation of the Department's database of patients with papillary thyroid carcinoma who had undergone total thyroidectomy from January 1992 to December 2000. Group I consisted of 83 DSV patients and Group II was 168 pure papillary carcinoma (PC) patients. A significant prevalence of multinodular thyroid disorder on diagnosis was found for PC (P < 0.05), whereas with DSV, there was a significantly higher prevalence of post-thyroiditis nodular thyroid disorder than with PC (P < 0.001). The incidence of laterocervical lymph node pathology on diagnosis was significantly higher for DSV (P < 0.05). In 3.6 per cent of PC patients and 15.7 per cent of DSV patients, we observed recurrences in the regional lymph nodes (P < 0.001). We found 1.2 per cent distant metastases in PC patients and 7.2 per cent in DSV patients (P < 0.05). One PC patient (0.6%) and three DSV patients (3.6%) died of tumor-related causes (P < 0.05). Our study demonstrated that diffuse sclerosing carcinoma leads to a poorer prognosis to the extent that its classification as an autonomous clinical pathological entity is justified. In conclusion, we can state that DSV is a form of papillary thyroid tumor characterized by its higher aggressiveness, diffuse intrathyroid growth, and high incidence of lymph node and pulmonary metastasis. Ultimately, this means a poorer prognosis. In the presence of risk factors indicating a possible increase in biological aggressiveness, adequate postoperative treatment and close follow-up become essential.

Poorly differentiated carcinomas of the thyroid with trabecular, insular, and solid patterns: a clinicopathologic study of 183 patients

BACKGROUND

The term poorly differentiated (PD) carcinoma was proposed 20 years ago to define aggressive, follicular-derived thyroid carcinomas with behavior intermediate between follicular/papillary and anaplastic carcinomas. Among the variable histologic patterns recognized in such tumors, trabecular-insular-solid (TIS) areas usually are predominant. Conversely, some authors pointed out that PD carcinomas are characterized by unequivocal, high-grade histology with atypias, high mitotic counts, and necrosis rather than by a specific growth pattern.

METHODS

The clinicopathologic features of a series of 183 thyroid carcinomas with predominant (n = 165 tumors) or focal (n = 18 tumors) TIS growth patterns were studied by univariate and multivariate overall survival analyses and were compared with clinical outcomes. Subgroups included tumors with predominant oxyphilic features (n = 66 tumors) and (residual) papillary carcinoma features (n = 24 tumors). Control groups of papillary (n = 68 tumors), follicular (n = 71 tumors), and anaplastic (n = 35 tumors) carcinomas also were included for overall survival analysis.

RESULTS

TIS carcinomas had an intermediate behavior between papillary/follicular and anaplastic carcinomas (P < 0.0001). Univariate and multivariate statistical analyses demonstrated that age > 45 years (P = 0.007), the presence of necrosis (P < 0.0001), and a mitotic count > 3 per 10 high-power fields (P = 0.01) were associated with poor outcome. A simplified scoring system based on statistically significant parameters allowed the identification of three prognostic subgroups (P < 0.0001).

CONCLUSIONS

PD TIS carcinomas overall followed a more aggressive course compared with differentiated thyroid carcinomas, irrespective of the extent of the TIS component. However, a numeric scoring system applied to specific clinicopathologic parameters further may identify three prognostic categories of patients who have significantly different survival rates at 5 years and 10 years.

A review of thyroid cancer with intermediate differentiation

BACKGROUND AND OBJECTIVES

Tall cell (TCV), columnar cell (CCV), insular (IC), diffuse sclerosing (DSPTC) and solid/trabecular are uncommon subtypes of thyroid cancer, which have generally been described in case reports or small series in the world literature. Due to the rarity of these thyroid cancers, their clinical behavior remains incompletely understood. The aim of this review was to pool the currently available clinical information regarding these uncommon thyroid cancers so as to gain a better understanding of their clinical aspects and natural history.

METHODS

A computer-aided search of MEDLINE (1966-2001, PUBMED website) and CINAHL (1982-2001) databases was performed, as well as a review of the reference section of each primary study was done. All cases of TCV, CCV, DSPTC, solid/trabecular, and IC described in the English medical literature were identified. For the subtypes DSPTC, TCV, and IC, clinical data from the published case series were combined in a weighted analysis. Weighting was based on the number of cases per series. For the CCV and the solid/trabecular variant, due to the small number of cases, raw figures for the clinical features were obtained.

RESULTS

DSPTC (n = 65) appeared to have a tendency for intra-thyroidal extension (40%) and a high propensity for nodal metastates (68%). The mean overall tumor related mortality was similar to well differentiated thyroid cancer (WDTC) at only 2% at 8 years follow-up. The solid/trabecular variant was seen in 37% of the radiation induced thyroid tumors of the Chernobyl accident. It had a high propensity for extrathyroidal extension, and cervical lymph node metastases were found in up to 83% of patients. Unlike WDTC, TCV (n = 209) was a more aggressive tumor, associated with distant metastases in 22% of cases and had a mean tumor related mortality of 16%. The histological diagnosis of TCV was a poor prognostic factor regardless of patient age or tumor size. The CCV (n = 41) had a high overall mortality rate of 32%. When encapsulated, however, CCV had an excellent prognosis similar to that found in WDTC. In contrast, CCV tumors that were not encapsulated had extrathyroidal spread in 67% and had distant metastases in 87% of patients. The variant of IC (n = 213) appeared to be an aggressive subtype of thyroid cancer. The mean loco-regional recurrence and/or distant metastases rate was 64% and tumor related mortality was high at 32%.

CONCLUSIONS

DSPTC, TCV, CCV, and IC are thyroid cancer subtypes, which have a biological aggressiveness, which appear to be intermediate between that of WDTC and poorly differentiated anaplastic thyroid cancer. J. Surg. Oncol. 2004;86:44-54.

Extrathyroid spread in papillary carcinoma of the thyroid: clinicopathological and prognostic study

INTRODUCTION

The extrathyroid spread (ETS) is one of the risk factors that influence mortality and recurrence in patients with papillary carcinoma of the thyroid (PCT). The aim of this study is to analyze the clinical and histologic features and follow-up of a series of patients with ETS undergoing surgery for PCT and to identify patients with a greater risk of presenting with ETS.

MATERIAL AND METHODS

Retrospective study of a series of 200 patients undergoing surgery for PCT, of whom 47 (23.5%) presented with ETS. The clinical and histologic features and follow-up of the patients with ETS were compared with those without ETS using the Pearson chi(2) test. We used a logistics regression model to perform a multivariant analysis for ETS. The survival and disease-free interval rates were calculated using the Kaplan-Meier method.

RESULTS

ETS is most associated with patients over 50 years of age, with tumors over 4 cm that are not encapsulated, with lymph node metastasis, and with certain PCT histologic subtypes after the multivariant analysis. The overall rate of recurrence and mortality in patients with ETS was much higher than in patients without ETS.

CONCLUSIONS

PCT patients with ETS have a greater risk of tumor-related recurrence and mortality than patients without ETS. There are patients with certain clinical and histologic features who have a greater risk of presenting with ETS.

Thyroid cytology and histology

Fine needle aspiration (FNA) is an economical procedure that allows prompt evaluation of a thyroidal mass. Careful attention to each step of the aspiration will allow good specimens to be obtained. The cytopathologist should obtain the aspirates or else should accompany the clinician performing the aspirations. Unsatisfactory specimens should constitute less than 5% of the total. Reliable diagnoses can be made of papillary carcinoma, medullary carcinoma, anaplastic carcinoma, chronic lymphocytic thyroiditis, benign cystic lesions and the usual colloid-rich adenomatoid nodules. The diagnosis of follicular neoplasms and some cellular adenomatoid nodules remains problematical. Therefore, some thyroid operations inevitably yield benign follicular lesions.

Encapsulated follicular variant of papillary thyroid carcinoma with bone metastases

Although true follicular thyroid carcinoma is known to metastasize via the bloodstream and give rise to bone and lung metastases, such a pattern of spread is rare in papillary thyroid carcinoma. The follicular variant of papillary thyroid carcinoma (FVPTC) is believed to behave in a clinical manner similar to usual or classical papillary cancer and to follow a similar indolent course. There have been a few reports of "aggressive" FVPTC wherein follicular patterned tumors with nuclear features of papillary carcinoma have metastasized hematogenously; these neoplasms have been diffusely invasive or multicentric in the thyroid. We report five cases of FVPTC, which were encapsulated and simulated grossly and microscopically follicular adenomas. In two of these, the primary was discovered after clinical presentation of bone metastases. In three others, bony metastases (without other nonosseous metastases) arose 7 to 17 years after thyroid lobectomy for lesions initially diagnosed as follicular adenoma In retrospect, these three encapsulated lesions had vascular invasion. We wish to bring attention to these innocuous-appearing lesions, which, although sharing nuclear features of papillary cancer, behave clinically in an unexpectedly malignant fashion.

Diagnosis of malignant epithelial thyroid lesions: fine needle aspiration and histopathologic correlation

Fine needle aspiration is a diagnostic tool useful as a guide to patient management. We believe that its role in solving the diagnostic dilemmas presented by thyroid nodules is still underappreciated. Current fiscal constraints in health care might bring about a wider use of this simple technique to select patients for surgery. Care in sampling a mass is essential to obtain aspirates that are representative of the lesion and adequate in quantity for interpretation. Several aspirates are needed from all but the smallest masses. Most thyroid carcinomas are well-differentiated with a low grade of malignancy. The majority of these are papillary carcinomas, which are easily diagnosed in good cytologic smears. With fine needle aspirates the goal is to diagnose a follicular neoplasm and to separate it from the adenomatoid nodule. The follicular neoplasm then can be classified as adenoma or carcinoma with the histologic sections. The minimally invasive carcinoma still can be challenging to recognize. We hope that the cytologic criteria and histopathologic correlations presented here will help general pathologists who interpret aspirates. We believe that in the near future additional immunohistochemical methods and genetic markers will be used increasingly to discriminate among the neoplasms and to provide prognostic information.

Management of the neck in thyroid cancer

The incidence of nodal metastasis in differentiated thyroid cancer ranges between 40% to 75%. Elective neck dissection is generally not advised in patients with differentiated thyroid cancer; however, if clinically apparent nodal disease is noted in the tracheoesophageal groove during surgery, central compartment clearance is advised. If clinically apparent nodal disease is present in the lateral compartment of the neck, modified neck dissection preserving the sternomastoid, accessory nerve, and jugular vein is advised. The "berry picking procedure" is generally not recommended because of the higher incidence of regional recurrence. Due consideration should be given for parathyroidal transplantation if the blood supply to the parathyroids is damaged during central compartment clearance. The incidence of lymph node metastasis is highest in young patients, however, lymph node metastasis has no bearing on long-term survival. There seems to be a higher incidence of regional recurrence in elderly individuals. If patients present with bulky nodal disease, consideration may be given for postoperative radioactive iodine dosimetry and ablation if necessary. Differentiated thyroid cancer represents a unique disease in the human body, where lymph node metastasis has no prognostic implication. Aggressive surgical clearance is advised in patients with medullary thyroid cancer in the central compartment and the jugular chain lymph nodes.

Medullary thyroid carcinoma experienced at Kanazawa University Hospital

Eleven cases of medullary thyroid carcinoma (MTC), which were experienced at Kanazawa University Hospital between 1975 and 1993, were examined to correlate the clinical, histologic, and immunohistochemical findings. Seven patients were women and four men, and the mean age was 46.6 years. The mean follow-up was 88.3 months. Three patients had familial non-multiple endocrine neoplasia (MEN) MTC (familial MTC unassociated with other endocrinopathies) and the remaining eight had sporadic disease. At the end of the observation period, six patients were alive without disease and four were alive with metastatic disease. One patient died of MTC 8.3 years after surgery. Thus, the 10-year survival and disease-free survival rates were 67% and 53%, respectively. Histologically MTCs from the 10 surviving patients showed a classic type, while the one patient who died had a tubular variant MTC. Immunohistochemically, there were no significant correlations between the outcome of the patients and the expression of calcitonin (CT), carcinoembryonic antigen (CEA), calcitonin gene-related peptide (CGRP), or chromogranin A (CgA) in the primary tumors, and there were no differences in expression of these antigens between the primary and the recurrent tumors. Although only a small number of patients with MTC were studied here, it was suggested that the prognosis of MTC is worse than that of papillary and follicular thyroid carcinoma. The patients with lymph node involvement at the time of primary surgery showed a high risk of persistent or recurrent disease. The expressional level for the antigens did not influence the prognosis of MTC.

Multivariate analysis of histopathological features as prognostic factors in patients with papillary thyroid carcinoma

A retrospective analysis of 121 papillary thyroid carcinomas was made to assess prognostic factors including histological variants which might be related to survival. The mean follow-up period was 10 years and clinical, surgical and histopathological data were studied. The survival curves were analysed by the Kaplan-Meier method and the multivariate analysis used Cox's regression model. Eighty-seven patients had well differentiated papillary cancers. The survival rate for papillary thyroid cancer was 86 per cent at 5 years and 72 per cent at 10 years. Factors showing prognostic significance for survival were tumour size, extrathyroid extension and histological type. Disease-free survival was influenced by sex, existence of a capsule and nodal metastases. Factors showing a favourable prognosis were: age under 45 years, size less than 4 cm, no extrathyroid extension and well differentiated histological type (P < 0.001). Histological subtype was one of the most important prognostic factors.

Columnar cell carcinoma of the thyroid gland: a case report and review of the literature

A rare case of columnar cell carcinoma of the thyroid gland is reported. The tumor was characterized by a predominantly papillary proliferation of tall columnar cells with marked nuclear stratification with associated focal areas showing solid or microfollicular growth. The nuclei of the tumor cells did not have the ground-glass appearance that characterizes papillary thyroid carcinoma; rather their nuclear features resembled follicular carcinoma. The tumor was found in an advanced stage and the patient died of lung metastases 2.5 years after surgery. The unique histopathological features and highly aggressive nature of columnar cell carcinoma require that this variant be differentiated from common papillary carcinoma of the thyroid. We also reviewed the literature emphasizing the lethal biological nature of this variant.

Selective activation of ras oncogenes in follicular and undifferentiated thyroid carcinomas

A total of 96 tumour samples (88 primary tumours and 8 nodal metastases) from 88 patients with thyroid adenomas and carcinomas were investigated for ras gene mutations using polymerase chain reaction, oligonucleotide probing and sequencing. Neither the 19 adenomas nor the 31 papillary carcinomas analysed harboured point mutations. In our cases, mutations in all three ras oncogenes were found in follicular carcinomas (five out of 21) and in the less differentiated thyroid tumour: poorly differentiated carcinomas (three out of 11) and undifferentiated carcinomas (one out of five). Finally, mutated ras oncogenes had a significant association with the appearance of haematogenous (particularly bone) metastases, suggesting a role of ras genes activation in the metastatic capability of these tumours.

Gene p53 mutations are restricted to poorly differentiated and undifferentiated carcinomas of the thyroid gland

The p53 gene was analyzed in tumor specimens obtained from 52 patients with various types of carcinoma of the thyroid gland by a combined molecular and immunocytochemical approach. The histologic types included 37 well-differentiated papillary and follicular carcinomas, 8 poorly differentiated, and 7 undifferentiated carcinomas. The p53 gene was shown to be unaffected in all differentiated tumors by single-strand conformation polymorphism analysis. However, in two out of eight (25%) of poorly differentiated carcinomas and five out of seven (71%) undifferentiated carcinomas, p53 mutations were identified and subsequently characterized by DNA sequencing. One undifferentiated carcinoma displayed two areas with varying degrees of differentiation. The comparative analysis of the p53 gene, in both the more and the less differentiated area of this tumor, clearly showed that the p53 mutation was confined to the latter component of the tumor specimen. These results indicate that mutations of the p53 gene are associated with the most aggressive histologic types of thyroid tumors, such as the undifferentiated carcinoma and, to a certain extent, the poorly differentiated carcinoma, and that the alterations of this gene represent a late genetic event in human thyroid carcinogenesis.