Prevalence and biological behaviour of variants of papillary thyroid carcinoma: experience at a single institute

Study to Evaluate the Pattern of Nodal Distribution in Papillary Thyroid Cancer

Among the thyroid cancers, papillary thyroid cancer (PTC) is the most common with lymphatic metastasis. It has the propensity to spread to the level II-VI lymph nodes in a predictable manner. We evaluated the pattern of nodal distribution at different levels of neck in papillary thyroid cancer in this Observational Prospective study. Total 41 patients of PTC (Papillary thyroid cancer) were included in the study. 36 out of them were diagnosed as PTC by FNAC and underwent total thyroidectomy and central neck dissection, while 5 patients were histologically confirmed cases of PTC on previous hemithyroidectomy and underwent completion thyroidectomy and central neck dissection .Patients with T3/T4 stage or N1 underwent lateral neck dissection also. Clinicopathological factors such as age, sex, tumor stage, nodal metastasis and extracapsular invasion, were evaluated. Lymph node metastasis was noted in 21 patients (51.2%) and all these patients had central (level VI) lymph node involvement. Among 21 patients, pathological ipsilateral lateral neck metastasis was noted in 6 patients (28.57%) at level II, 10 patients (47.62%) at level III and 8 patients (38.10%) at level IV. Only 5 patients (23.81%) had metastasis at level V. Extracapsular invasion was observed in 10 (24.4%) patients. We concluded that patients with PTC show higher rates of metastasis at central neck (level VI) and are not easily detected on clinical examination or by USG due to low sensitivity but are sensitive and specific for lateral neck nodes in late stages . Thus, ipsilateral selective neck dissection should be considered with total thyroidectomy and central neck dissection in presence of clinically or radiologically evident lateral lymph nodes (preoperatively) and in T3, T4 stage (late stages) tumors.

Clinicopathological Characteristics and Recurrence-Free Survival of Rare Variants of Papillary Thyroid Carcinomas in Korea: A Retrospective Study

BACKGROUND

We aimed to evaluate the clinicopathological features and biological behaviors of Korean thyroid cancer patients with rare variants of papillary thyroid carcinoma (PTC) to address the ambiguity regarding the prognostic consequences of these variants.

METHODS

We retrospectively reviewed the medical records of 5,496 patients who underwent thyroid surgery for PTC, between January and December 2012, in nine tertiary hospitals. Rare PTC variants included tall cell (TCV), columnar cell (CCV), diffuse sclerosing (DSV), cribriform-morular (CMV), solid (SV), hobnail, and Warthin-like variants. Recurrence-free survival (RFS) was defined as the time from the date of thyroidectomy until recurrence.

RESULTS

Rare variants accounted for 1.1% (n=63) of the PTC patients; with 0.9% TCV, 0.02% CCV, 0.1% DSV, 0.1% CMV, and 0.1% SV. The mean age of patients and primary tumor size were 42.1±13.1 years and 1.3±0.9 cm, respectively. Extrathyroidal extension and cervical lymph node metastasis were observed in 38 (60.3%) and 37 (58.7%) patients, respectively. Ultrasonographic findings revealed typical malignant features in most cases. During a median follow-up of 7 years, 6.3% of patients experienced a locoregional recurrence. The 5-year RFS rates were 71.4% in patients with DSV or SV, 95.9% for TCV, or CCV, and 100% for other variants. DSV emerged an independent risk factor associated with shorter RFS.

CONCLUSION

In this multicenter Korean cohort, rare variants accounted for 1.1% of all PTC cases, with TCV being the most frequent subtype. DSV emerged as a significant prognostic factor for RFS.

Special types of thyroid carcinoma

This article reviews the small percentage of thyroid tumours that are not classified as classic papillary thyroid carcinoma, follicular thyroid carcinoma, and medullary thyroid carcinoma. It includes subtypes of papillary thyroid carcinoma, including, tall-cell, hobnail/micropapillary, columnar cell, diffuse sclerosing and solid variants. Poorly differentiated carcinoma, high-grade carcinoma and anaplastic thyroid carcinoma are reviewed. Also discussed are entities that are unusual but need to be recognized as primary thyroid neoplasms, i.e. mucoepidermoid carcinoma, sclerosing mucoepidermoid carcinoma with eosinophilia, and mammary analogue secretory carcinoma/secretory carcinoma. The pathological features and prognostic factors are described; a brief review of molecular correlates of these neoplasms is included.

A comparison of the clinicopathological features and prognoses of the classical and the tall cell variant of papillary thyroid cancer: a meta-analysis

Papillary thyroid cancer (PTC) accounts for 80–90% of all thyroid malignancies. The tall cell variant (TCV) is a rare aggressive histotype of PTC. We performed a meta-analysis to compare the clinicopathological characteristics and prognostic factors of TCV with those of classical papillary thyroid carcinoma (cPTC). A literature search was performed using the PubMed and EMBASE databases using Medical Subject Headings and keywords. Twenty studies that included 1871 patients with TCV and 75323 patients with cPTC were included in our meta-analysis. Odds ratios and confidence intervals were calculated for each study. Patients with TCV were associated with multifocality, higher TNM stage, extrathyroidal extension, vascular invasion, lymph node metastasis, distant metastasis, BRAF mutation, disease-specific survival, and overall survival. We found that TCV cases were associated with more aggressive clinicopathological characteristics and poorer prognoses than cPTC cases were. Our results suggest that TCV is a high-risk PTC that warrants aggressive treatment and follow-up strategies.

Follicular morphological characteristics may be associated with invasion in follicular thyroid neoplasms with papillary-like nuclear features

The newly proposed nomenclature and diagnostic criteria for encapsulated follicular variant of papillary thyroid carcinoma (EFVPTC), the noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP), could improve the consistency and accuracy of diagnosing this entity. Diagnosis of NIFTP requires evaluation of the complete tumor border or capsule. The presence of tumor invasion in follicular thyroid neoplasms with papillary-like nuclear features has been recently discussed by many authors. In this study, we examined the predictive value and association of follicular morphological characteristics with the tumor invasion. In addition, we analyzed the association between tumor encapsulation and molecular profile in EFVPTC/NIFTP cases. A total of 106 cases of FVPTC were included in the study. The tumors were grouped based on the presence of tumor capsule and characteristics of tumor border, as 1) completely encapsulated tumors without invasion, 2) encapsulated tumors with invasion, 3) infiltrative tumors without a capsule. Clinicopathological features, histomorphological features [nuclear criteria, minor diagnostic features, follicles oriented perpendicular to tumor border/capsule (FOPBC)] and molecular alterations in BRAF, NRAS, and KRAS genes were evaluated. FOPBC were significantly more frequently seen in encapsulated tumors with invasion (p = 0.008). The nuclear features were not associated with the presence of encapsulation and characteristics of tumor border. BRAF mutation was more frequent in infiltrative tumors, while NRAS mutation was more frequent in encapsulated tumors, but the results were not statistically significant (p = 0.917). In conclusion, FOPBC histomorphological feature may be associated with tumor invasion in EFVPTC/NIFTP. Additionally, BRAF/KRAS/NRAS mutation analysis may prevent inadequate treatment in these patients.

Recent incidences and differential trends of thyroid cancer in the USA

The incidence rate of thyroid cancer has been rising rapidly in recent decades; however, its trend remains unclear. To investigate this, we analyzed the database of the Surveillance, Epidemiology and End Results (SEER) 13, 1992-2012 in the USA, particularly focusing on conventional papillary thyroid cancer (CPTC) and follicular variant of PTC (FVPTC). Of the 75,992 thyroid cancers, 61.3% were CPTC and 25.7% were FVPTC, and their incidence rates (IRs) were significantly increased from 1992 to 2012 (P all < 0.001), with CPTC being 2.4 times of FVPTC (P < 0.001) and the overall average annual percent change (AAPC) of incidence being 6.3% in the former and 5.3% in the latter. IRs were increased in all thyroid cancers, albeit most dramatically in PTC, in virtually all ethnic/demographic groups in recent two decades; however, the incidence trends varied among different thyroid cancers, particularly differentiable between CPTC and FVPTC. For example, Joinpoint analyses revealed that the APC of CPTC before 1996 was 1.5% (P > 0.05), which jumped to 6.8% (P < 0.05) after 1996, whereas the APC of FVPTC before 2000 was 6.6% (P < 0.05), which dropped to 4.8% (P < 0.05) after 2000. IRs and incidence trends of PTC were uneven among different ethnic/demographic groups, as exemplified by the lower IRs of both PTC variants in the Black females than in non-Hispanic White females but higher AAPCs of incidence in the former than in the latter. Interestingly, the data also suggest that the rise in the IRs of PTC is becoming plateaued in the most recent 2 years. These novel observations are helpful in understanding the incidence and incidence trends of thyroid cancer.

First-Line Use of Vemurafenib to Enable Thyroidectomy and Radioactive Iodine Ablation for BRAF-Positive Metastatic Papillary Thyroid Carcinoma: A Case Report

Background. Patients with metastatic or radioactive iodine refractory papillary thyroid carcinoma (PTC) have poor prognosis due to ineffective therapy for this condition beyond surgery and radioactive iodine (RAI or ¹³¹I). BRAF mutation occurs in more than 44% of PCT. Tyrosine kinase inhibitors, the most commonly used agents for these patients, have weak BRAF inhibition activity. BRAF inhibitors have demonstrated promising efficacy in relapsed metastatic PCT after standard treatment, though they are not currently approved for this indication. Case Presentation. We present the case of a 48-year-old Hispanic male who initially presented with columnar-cell variant subtype of PTC and positive BRAFV600E mutation. The patient had widespread bulky metastases to lungs, chest wall, brain, and bone. Discussion. Initial use of vemurafenib demonstrated a 42% cytoreduction of targeted pulmonary metastases and facilitated thyroidectomy and RAI treatment. The patient achieved a durable response over 21 months in the setting of widely metastatic disease. Conclusion. Vemurafenib may be effectively used for cytoreduction in patients with bulky metastatic PTC to bridge them to thyroidectomy and RAI treatment.

A Clear Cell Variant of Papillary Thyroid Microcarcinoma With Lung, Bone, and Soft Tissue Metastases

A 56-year-old woman presented with a mass lesion on the right occipital bone underwent total resection of the tumor. An adenocarcinoma with immunostaining positive for thyroid transcription factor-1 and thyroglobulin was found. An ultrasound/thyroid scan detected a hot nodule of 9 mm in the right lobe. Fine needle biopsy revealed the similar histological findings with the previous bone resection material. Then, a total thyroidectomy was performed. Histopathologic examination revealed clear cell variant of papillary thyroid microcarcinoma. She received 7.4 GBq of I. On posttherapy scan, metastatic focuses were seen in the left lung and soft tissue between the left paravertebral muscles.

Comparison of the clinicopathological behavior of the follicular variant of papillary thyroid carcinoma and classical papillary thyroid carcinoma: A systematic review and meta-analysis

The follicular variant of papillary thyroid carcinoma (FV-PTC) is the second most common type of papillary thyroid carcinoma (PTC), and it has been increasingly diagnosed in recent years. However, whether FV-PTC behaves differently from classical PTC (C-PTC) remains controversial. To address this controversy, a meta-analysis was performed to determine the potential differences between FV-PTC and C-PTC in their clinicopathological behavior. The relevant published studies between January 1, 2003 and August 31, 2014 were reviewed according to the defined selection criteria using the PubMed database. Review Manager was used to calculate the pooled odds ratio (OR) or the mean difference (MD) with a 95% confidence interval (CI), using a random- or fixed-effect model for all analyses. In total, 112 studies were identified and examined; finally, only 36 studies met the inclusion criteria. In the 36 studies, compared to the clinicopathological behavior of patients with C-PTC, patients with FV-PTC had the following parameters: Similar mean age and similar prevalence of gender, tumor size ≥10 mm, multifocality, capsular invasion, vascular invasion, lymphocytic and/or Hashimoto's thyroiditis, and clinical stage; a larger mean tumor size and higher prevalence of age ≥45 years; and lower prevalence of extrathyroidal extensions, lymph node metastases, BRAF mutation and recurrence. The meta-analysis suggested that patients with FV-PTC have a more favorable clinicopathological behavior and improved prognosis compared to patients with C-PTC. Thus, patients with FV-PTC and C-PTC may be managed differently, and the two types of PTC should be clearly distinguished in future retrospective or prospective studies.

Variants of papillary thyroid carcinoma: association with histopathological prognostic factors

Papillary carcinoma is the most common thyroid malignancy. Many variants of this tumor have been described, with different morphological and molecular characteristics. Although most cases have excellent prognosis, the relationship between tumor architecture and its biological behavior remains controversial.

Objective

To present the experience of a single center on the prevalence of thyroid papillary carcinoma variants and their relationship with other histopathological prognostic factors.

Method

Retrospective study of all the cases submitted to thyroidectomy for papillary carcinoma in the same institution over 11 years.

Results

We included 517 patients, 81.9% of them were women. The average age was 47.2 years. The variants recognized to have higher aggressiveness potential corresponded to 5.6% of the sample. We found an association of tumor subtypes with greater lesion diameter, T staging, lymphovascular and gland capsule invasion.

Conclusion

A small percentage of papillary carcinoma cases is represented by variants recognized by their greater potential for aggression. There are associations between these variants and several other histopathological factors already recognized for their prognostic value, which may, by themselves, influence the outcome of these cases.

Macrofollicular variant of papillary thyroid carcinoma with extensive lymph node metastases

The macrofollicular variant of papillary thyroid carcinoma is a rare subtype of the follicular variant of papillary thyroid carcinoma and is usually characterized by an indolent clinical course. The tumors are prone to be misdiagnosed as benign due to their macrofollicular architecture and bland cytologic features. We report a rare case of the macrofollicular variant of papillary thyroid carcinoma with extensive lymph node metastases. The patient was a 48-year-old female with a right thyroid nodule and multiple enlarged lymph nodes in the right neck. It was not possible to make a definitive diagnosis of malignancy on fine-needle aspiration cytology and intraoperative frozen section. She underwent total thyroidectomy with right modified radical neck dissection. The surgical specimen showed a 2.5 × 1.5 × 10 cm, well-circumscribed macrofollicular variant of papillary thyroid carcinoma in the right lobe and multiple central and right lateral neck lymph node metastases. Molecular testing for BRAF, NRAS, HRAS, and KRAS was all negative. We then reviewed the demographic and clinicopathologic characteristics of 71 patients with the macrofollicular variant of papillary thyroid carcinoma. The cytologic or histopathologic diagnosis of macrofollicular variant of papillary thyroid carcinoma can be difficult. Extensive lymph node metastases caused by the macrofollicular variant of papillary thyroid carcinoma may occur even in the absence of capsular or lymphovascular invasion. This review will help to better understand the nature of the macrofollicular variant of papillary thyroid carcinoma.

The assessment of prognostic histopatholgical parameters depending on histological patterns of papillary thyroid carcinoma

Papillary thyroid carcinoma represents common injuries that can have different histological variants that may influence the patient’s prognostic. The study included a total of 44 papillary thyroid carcinomas, for which were followed a series of histological factors of aggressiveness for grading tumors. Most studied papillary carcinomas corresponded to the conventional type, followed by the follicular, micropapillary and tall cell variants. Depending on the presence of nuclear atypia, tumor necrosis, the frequency of mitosis, also the vascular invasion and the extrathyroidian extension there were distributions differences of the cases according to the tumor type, most of the cases belonged to the conventional and tall cell types. The assessment of histopathological parameters of aggressiveness with certain types known to have an unfavorable behavior, justify the use of the histological grading of papillary thyroid carcinomas.

Prognostic implications of papillary thyroid carcinoma with tall-cell features

BACKGROUND

The prognostic implications of the diagnosis of a papillary thyroid carcinoma (PTC) with tall-cell features are unknown.

METHODS

All PTC patients identified between 1985 and 2005 were analyzed histologically. Classical PTC cases were defined as having <30% tall cells, PTC with tall-cell features (PTC TCF) as 30%-49% tall cells, and tall-cell variant of PTC (TCV) as ≥ 50% tall cells. All classical PTC, PTC TCF, and TCV ≥ 1 cm in size were included.

RESULTS

A total of 453 patients satisfied the inclusion criteria (288 classical PTC, 31 PTC TCF, and 134 TCV). Classical PTC patients were younger than their PTC TCF and TCV counterparts (p<0.0002). There was an increase in tumor size from classical PTC to PTC TCF and TCV (p=0.05). Extensive extrathyroid extension and positive margins were more often present in TCV and PTC TCF than in classical PTC (p=0.0001 and p=0.03 respectively). Overall pathologic tumor (pT) stage was more advanced in TCV and PTC TCF than in classical PTC (p<0.0001). Total thyroidectomy and radioactive iodine therapy were more often performed and administered in TCV patients than in their PTC TCF and classical PTC counterparts (p=0.001 and p=0.0001 respectively). Median follow-up was 9.3 years. Ten-year disease-specific survival (DSS) was lower in TCV (96%) and PTC TCF (91%) than in classical PTC (100%; p<0.001). Ten-year distant recurrence-free survival (RFS) was higher in classical PTC (98%) than in PTC TCF (89%) and TCV (96%; p=0.03). In multivariate analysis, the presence of more than five positive nodes and extranodal extension were the only independent prognostic factors of neck and distant RFS respectively. Four (2.4%) of 165 PTC TCF and PTC TCV developed poorly differentiated or anaplastic carcinoma in their recurrence, while none of the 288 classical PTC transformed into higher grades (p=0.017).

CONCLUSIONS

PTC TCF and TCV have similar clinicopathologic features that are more aggressive than classical PTC. PTC TCF and TCV have similar DSS and distant RFS but poorer outcomes than classical PTC. PTC TCF are currently being treated like classical PTC, that is, less aggressively than TCV. PTC TCF and TCV TCV have a higher rates of high-grade transformation than classical PTC. Consideration should be given to using a 30% tall-cell threshold to diagnose TCV.

Static and dynamic prognostic factors of papillary thyroid carcinoma

The two types of prognostic factors of papillary thyroid carcinoma (PTC) are static and dynamic. The following static prognostic factors have been conventionally adopted: age, tumor size, extrathyroid extension, lymph node metastasis, and distant metastasis based on pre-, intra- and post-operative findings. These factors are useful to decide therapeutic strategies for PTC patients, including the extent of surgery and radioactive iodine (RAI) ablation. However, even the combination of these factors evaluated pathologically postoperatively is not good enough at predicting recurrence in clinical settings. The dynamic prognostic factors of changes in serum thyroglobulin (Tg) and thyroglobulin antibody (TgAb) values in patients who have undergone a total thyroidectomy are important to evaluate the progression of carcinoma recurrence and to predict patients' cause-specific survival, regardless of their backgrounds and the clinicopathological features of their PTC. Dynamic prognostic factors are superior to static prognostic factors in terms of expressing the condition of recurrence on a real-time basis.

Genetic alterations in thyroid tumors from patients irradiated in childhood for tinea capitis treatment

OBJECTIVE

Exposure to ionizing radiation at young age is the strongest risk factor for the occurrence of papillary thyroid carcinoma (PTC). RET/PTC rearrangements are the most frequent genetic alterations associated with radiation-induced PTC, whereas BRAF and RAS mutations and PAX8-PPARG rearrangement have been associated with sporadic PTC. We decided to search for such genetic alterations in PTCs of patients subjected in childhood to scalp irradiation.

DESIGN

We studied 67 thyroid tumors from 49 individuals irradiated in childhood for tinea capitis scalp epilation: 36 malignant (12 cases of conventional PTC (cPTC), two cPTC metastases, 20 cases of follicular variant PTC (FVPTC), one oncocytic variant of PTC and one follicular carcinoma) and 31 follicular thyroid adenomas.

METHODS

The lesions were screened for the BRAF(V600E) and NRAS mutations and for RET/PTC and PAX8-PPARG rearrangements.

RESULTS

BRAF(V600E) mutation was detected in seven of 14 (50%) cPTC and two of 20 FVPTC (10%) (P=0.019). NRAS mutation was present in one case of FVPTC (5%). RET/PTC1 rearrangement was found, by RT-PCR, in one of 17 cases (5.9%) and by fluorescence in situ hybridization in two of six cases (33%). PAX8-PPARG rearrangement was not detected in any carcinoma. None of the follicular adenomas presented any of the aforementioned genetic alterations.

CONCLUSIONS

The prevalence of BRAF(V600E) mutation in our series is the highest reported in series of PTCs arising in radiation-exposed individuals. The prevalence of RET/PTC1 rearrangement fits with the values recently described in a similar setting.

Correlation of immunohistochemical markers and BRAF mutation status with histological variants of papillary thyroid carcinoma in the Korean population

Several pathologic characteristics are associated with an adverse clinical outcome in papillary thyroid carcinoma (PTC), including the histological variant. This study aimed to investigate immunohistochemical expression and BRAF mutation status based on the histological variant and evaluated potential markers of aggressive behavior of PTC in Korean patients. In all, 407 PTC cases were classified to each histological variant, and the 94 representative cases were subjected to immunohistochemistry and BRAF mutation analysis. The classic type, follicular variant (FV) and tall cell variant (TCV) represented 76.9%, 14.2% and 6%, respectively. TCV showed a larger tumor size (P = 0.009), frequent extrathyroidal extension (P = 0.022) and cervical lymph node (LN) metastasis (P = 0.018). TCV and FV showed the reduced expression of galectin-3 (P = 0.003) and HBME1 (P = 0.114). Regardless of histology, PTEN loss and diffuse S100A4 expression were associated with LN metastasis (P = 0.007, P = 0.013). All TCVs harbored BRAF V600E mutation, and FV harbored less BRAF V600E mutation (P = 0.043). Immunohistochemical evaluation showed characteristic patterns in histological variants. PTEN and S100A4 expression are suggested as indicators of regional lymph node metastasis.

Cytological features of clear cell thyroid tumors, including a papillary thyroid carcinoma with prominent hobnail features

Primary thyroid tumors with extensive clear cell changes are extremely rare. More than 10,000 ultrasound-guided thyroid fine needle aspirations examined over a period of 17 years by the first author, only one of the 530 (<0.2%) papillary thyroid carcinomas (PTCs) and three of the 42 (7.1%) follicular thyroid carcinomas (FTCs) had extensive cytoplasmic clearing. Thyroidectomies were performed for these cases at four different hospitals in New York City. Final pathology was available for review in each of the four cases. Histology showed a 1.5-cm PTC with prominent hobnail features and clear cell change in a 31-year-old woman, a 4.3-cm FTC without angioinvasion in a 31-year-old woman, a 4.5-cm angioinvasive FTC in a 45-year-old man, and a 2-cm FTC with extensive angioinvasion in a 41-year-old woman with McCune-Albright syndrome (previously published). On ultrasound, the FTCs were solid circumscribed nodules and the PTC had an irregular margin. In these cases, the etiology for the cytoplasmic clearing included accumulation of glycogen in the PTC, accumulation of vesicles in two of the FTCs, and accumulation of lipid droplets in a FTC with extensive angioinvasion. Review of the cytologic literature showed 17 cases of follicular-derived thyroid tumors with extensive clear cell change. To the best of our knowledge, this is the first cytologic report of PTC with hobnail features and extensive clear cell change.

Euthyroid status after total thyroidectomy due to functioning lung metastases from a clear cell variant of papillary thyroid carcinoma

BACKGROUND

Although functioning thyroid cancer metastases have been reported, they have almost never been reported for the clear cell variant of papillary thyroid carcinoma (PTC). Here we describe a patient with disseminated lung metastases of the clear cell variant of PTC who presented in the euthyroid state despite discontinuance of levothyroxine after total thyroidectomy.

PATIENT FINDINGS

A 49-year-old woman underwent total thyroidectomy for the clear cell variant of PTC in March 2002. Levothyroxine replacement was initiated after total thyroidectomy, but the patient was lost to follow-up 5 years after the operation. She did not take any levothyroxine for 4 years. Upon presentation to our institution, her initial thyroid function tests were a serum thyroid-stimulating hormone (TSH) of 4.51 mIU/L (0.30-5.00), total triiodothyronine of 82 ng/dL (60-181), and free thyroxine of 1.21 ng/dL (0.89-1.76). The results of workups, including thyroid ultrasonography, chest computed tomography (CT) scan, and fluorine-18 fluorodeoxyglucose positron emission tomography (18F-FDG PET)/CT, revealed that she had multiple metastases in the cervical lymph nodes and both lungs. She received 0.9 mg of recombinant human TSH (rhTSH) for 2 consecutive days followed by administration of 200 mCi 131I. A therapeutic whole body scan after 131I administration demonstrated intense uptake in the whole lung fields, suggesting functioning lung metastases.

SUMMARY

It is extremely rare for metastatic PTC, even though it is a well-differentiated thyroid carcinoma, to produce a sufficient amount of thyroid hormones to result in euthyroid state after total thyroidectomy. To our knowledge, this is the first report of functioning lung metastases of the clear cell variant of PTC after total thyroidectomy that produced enough thyroid hormone to restore a euthyroid state.

CONCLUSION

Functioning metastases from recurred PTC, particularly of the clear cell variant, are very rare. When they occur, rhTSH is required to prepare these patients for treatment with ablative doses of radioactive iodine (131I).

Prognostic factors of papillary and follicular carcinomas in Japan based on data of kuma hospital

There are some important prognostic factors for papillary thyroid carcinoma (PTC) and follicular thyroid carcinoma (FTC). In this paper, clinicopathological features significantly affecting patient prognosis are described based on our data as well as others. Distant metastasis at diagnosis is the most important prognostic factor for both PTC and FTC. Other than that, preoperative and intraoperative findings are important to evaluate the biological behavior of PTC. Extrathyroid extension, large lymph-node metastasis, and extranodal tumor extension that can be evaluated preoperatively or intraoperatively are significant prognostic factors for PTC patients. In contrast, pathological findings are important not only for diagnosis of FTC, but also for the evaluation of its biological character. Grade of invasiveness (minimally or widely invasive) and degree of differentiation (well differentiated or including a poorly differentiated component) greatly affect the prognosis of FTC patients.

Tall cell variant of papillary thyroid carcinoma: sonographic and clinical findings

We retrospectively reviewed the clinical and sonographic features of 8 patients with 10 tall cell variants of papillary thyroid carcinoma. The mean age of the patients was 57 years (range, 34-72 years). The tumor sizes varied. Of the 8 patients, 5 had symptomatic masses, and 3 had incidentalomas. Three patients had recurrences and 1 died of pulmonary metastasis within a mean time of 30 months. The tall cell variants often appeared as microlobulated markedly hypoechoic nodules with microcalcifications and extrathyroidal extension on sonography and were always associated with lymph node metastasis. The tall cell variant of papillary thyroid carcinoma should be included in the differential diagnosis of an aggressive thyroid tumor with symptoms and cervical nodal metastasis.

Tumor margin histology predicts tumor aggressiveness in papillary thyroid carcinoma: a study of 514 consecutive patients

Histologic patterns at tumor margins may be related to prognosis in several malignancies. We investigated tumor aggressiveness with respect to tumor margin histology in patients with papillary thyroid carcinoma (PTC). Five hundred fourteen consecutive patients who underwent surgery for primary PTC between January and July 2009 were assigned to two groups, one with an infiltrative pattern (I-type, n = 347) at tumor margins and one with an expanding pattern (E-type, n = 167). Tumor aggressiveness was assessed by analyzing relationships between these patterns and known prognostic factors. The analysis showed that unfavorable prognostic factors such as tumor multiplicity (P = 0.002), extrathyroidal extension (P < 0.001), lateral neck lymph node metastasis (P < 0.001) and advanced TNM stage (P = 0.001) were significantly more prevalent in patients with I-type PTC than in those with the E-type. Central neck node metastases were more prevalent without statistical significance in the I-type patients (P = 0.376). Tumor margin histology was not related to gender or tumor size. These results suggest that histologic patterns at tumor margins predict aggressiveness in PTC.

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.

BRAF mutation in papillary thyroid carcinoma in a Japanese population: its lack of correlation with high-risk clinicopathological features and disease-free survival of patients

Recent studies have demonstrated that BRAF(V600E) mutation is a common event in papillary thyroid carcinoma and a majority of these lesions have shown a direct relationship between BRAF(V600E) mutation and aggressive characteristics, including a worse patient prognosis. However, there are no studies from Japan regarding this issue in a large series with adequate postoperative follow-up periods. We investigated BRAF(V600E) mutation in 631 patients with papillary carcinoma having median follow-up periods of 83 months. The prevalence of BRAF(V600E) mutation was 38.4%, and the rate was higher in carcinoma larger than 1.0 cm but did not successively increase with tumor size. Furthermore, the prevalence did not significantly increase in cases demonstrating high-risk biological features such as clinically apparent lymph node metastasis, massive extrathyroid extension, advanced age, distant metastasis at surgery, and advanced Stage. The disease-free survival of patients with BRAF(V600E) mutation did not differ from that of those without BRAF(V600E) mutation. These findings indicate that, although BRAF(V600E) mutation may play some roles in local carcinoma development, there is no evidence that BRAF(V600E) mutation significantly reflects the aggressive characteristics and poor prognosis of patients with papillary carcinoma in Japan.

Macrofollicular variant of papillary thyroid carcinoma: its clinicopathological features and long-term prognosis

Macrofollicular variant is a rare entity of papillary carcinoma. We previously demonstrated that this variant accounts for 0.3% of papillary carcinoma in Japan. In this study, we investigated the biological characteristics of 5 cases of macrofollicular variant. We reviewed the diagnosis and clinical course of 5 patients with macrofollicular variant. On preoperative ultrasonographic study, 2 cases were diagnosed as having benign nodule and the remaining 3 suspected of having papillary carcinoma, although they lacked typical ultrasonographic findings of papillary carcinoma. Cytological findings suggested papillary carcinoma for 3 cases and the remaining 2 were diagnosed as indeterminate. Based on both examinations, 4 of 5 patients were diagnosed as having or suspected of having papillary carcinoma. All patients underwent thyroidectomy with lymph node dissection. Three patients underwent central node dissection and the remaining 2 underwent modified radical neck dissection. None of these patients showed clinically apparent node metastasis or massive extrathyroid extension, although 3 of these patients had latent node metastasis confirmed by pathological examination. All patients survived with no evidence of carcinoma recurrence during follow-up (145-235 months). It is therefore suggested that patients with macrofollicular variant can be diagnosed as having or suspected of having papillary carcinoma if ultrasonographic and cytological examinations are appropriately performed and show an excellent prognosis possibly because this variant lacks the aggressive characteristics of papillary carcinoma.

Prognostic factors and therapeutic strategies for differentiated carcinomas of the thyroid

Differentiated thyroid carcinoma originates from thyroid follicular cells and is the most prominent malignancy of the endocrine organs. There are two histological types of differentiated carcinoma, namely, papillary and follicular carcinoma. According to reports from Western countries, papillary carcinoma comprises 85.3% of thyroid malignancies in whites, and 72.3% in blacks. In Japan, a previous study showed that the prevalence of papillary carcinoma was 78.4% based on material registered between 1977 and 1986, but according to recent findings reported in 2004 by Japanese Society of Thyroid Surgeons (JSTS), papillary carcinoma accounted for as much as 93% of all thyroid carcinomas. Papillary carcinoma frequently metastasizes to the regional lymph node and shows multicentricity in the thyroid gland. It usually shows a typical ultrasonographic appearance and can be rather easily diagnosed by fine needle aspiration biopsy (FNAB). Follicular carcinoma accounts for 10.9-20.5% of the patients in the United States. In Japan, the prevalence of follicular carcinoma was reported to be 17.2%, but it decreased to 5% in a report by JSTS in 2004. This carcinoma is only occasionally diagnosed preoperatively, because it is hard to discriminate follicular carcinoma from benign adenoma on imaging studies and cytologic findings. In contrast to papillary carcinoma, follicular carcinoma more often metastasizes to distant organs than regional lymph nodes. In Japan, the prevalence of papillary carcinoma increased and that of follicular carcinoma decreased between reports from 1977 to 1986 and that in 2004, which may be because follicular variant of papillary carcinoma was classified into follicular carcinoma in the previous results. Generally, these carcinomas show an indolent character, but when the lesion dedifferentiates and becomes undifferentiated carcinoma, it displays very rapid growth with an adverse prognosis and is regarded even as the most aggressive malignancy among human solid carcinomas. Furthermore, cases showing certain characteristics are likely to be constantly progressive and even become life-threatening. Such cases should be regarded as "high-risk" requiring careful and extensive surgical treatment and postoperative follow-up. Indeed, it is most important for physicians to correctly distinguish high-risk cases from those with an indolent character, although how to evaluate the biological characteristics of thyroid carcinoma and how to identify high-risk cases remains highly controversial. In this review, the methods of distinguishing high-risk cases and the appropriate therapeutic strategies for papillary and follicular carcinomas predominantly based on our experience are emphasized and our proposals for therapies including surgical treatment are demonstrated.