Ansa Cervicalis External Branch Anastomosis to Restore High Tone Voice in Thyroid Surgery

OBJECTIVES

Injury to the external branch of the superior laryngeal nerve (EBSLN) causes low-pitch voice and voice fatigue, particularly in female subjects, and available treatments are limited. Here, we assess a novel surgical procedure to restore a high-tone voice: ansa cervicalis to EBSLN anastomosis (A-E anastomosis).

METHODS

Between November 2012 and April 2022, 13 patients (12 female) underwent unilateral EBSLN resection and A-E anastomosis, while 20 (16 female) underwent EBSLN resection during thyroid surgery. Patients (4494 women and 1025 men) with normal laryngoscopy scheduled for thyroid surgery served as normal controls. Phonatory function was examined using a Phonation Analyzer PA-1000 preoperatively and intermittently postoperatively.

RESULTS

In patients who underwent A-E anastomosis, high-tone voice pitch decreased significantly postoperatively (673.9-471.5 Hz, p = 0.047), with restoration achieved within 5 months. The mean voice pitch in female patients who underwent A-E anastomosis, EBSLN resection, and controls were 580.4, 522.8, and 682.0 Hz, respectively, indicating a significant decrease in EBSLN resection patients than controls (p = 0.002). The (mean - 1SD) of high-tone voice pitch in female controls was 497 Hz; exceeding this may indicate recovery to a high-tone voice. Overall, 73% (8/11) of A-E anastomosis patients exceeded this value, which was marginally larger than the 43% (6/14) who underwent EBSLN resection. Data on male subjects are limited. There were no cases of adverse functional or cosmetic events.

CONCLUSIONS

A-E anastomosis, a novel simple procedure, restored high-tone voice to some extent without any adverse events and thus warrants further investigation.

LEVEL OF EVIDENCE

3 Laryngoscope, 2024.

Recurrent laryngeal nerve's course running anteriorly to a thyroid tumor

The thyroid gland's neurovascular relationship is commonly portrayed as the recurrent laryngeal nerve (RLN) coursing posteriorly to the thyroid gland. We report a rare case with the RLN running anteriorly to a thyroid tumor. A 56-year-old Japanese woman underwent a thyroidectomy for a benign thyroid tumor. Preoperatively, computed tomography confirmed that part of the tumor had extended into the mediastinum and was descending posteriorly up to the brachiocephalic artery. Intraoperatively, when the sternothyroid muscle was incised to expose the thyroid gland, a cord (nerve)-like structure was observed directly anterior to the thyroid tumor. Although the course of this cord-like structure was clearly different from the "traditional" course of the right RLN, the possibility that the structure was the RLN could not be excluded. The structure was traced back in order to preserve it; we saw that it entered the larynx at the lower margin of the cricothyroid muscle and approximately at the level of the cricothyroid junction through the back of the normal thyroid tissue. With intraoperative neuromonitoring, the structure was identified as the RLN. As a result, the course of the RLN run anterior to the tumor but then posterior to the 'normal thyroid' i.e. into it normal anatomical position. Had we assumed that the RLN was behind the thyroid tumor, we would have damaged the RLN. It would not be possible to diagnose this abnormal running course of the RLN reliably before surgery, but extra care should be taken in similar cases, that is, when a large thyroid tumor is descending posteriorly up to the brachiocephalic artery on the right side.

Long-term outcomes of active surveillance and immediate surgery for adult patients with low-risk papillary thyroid microcarcinoma: 30-year experience

BACKGROUND

It has been 30 years since the initiation of active surveillance (AS) for adult patients with low-risk papillary thyroid microcarcinoma (PTMC). This study compared the long-term oncological outcomes of patients who underwent AS or immediate surgery (IS).

METHODS

This is a retrospective review of extended follow-up data from patients enrolled in a single-center prospective, observational study in Japan. In total, 5646 patients diagnosed with low-risk PTMC at Kuma Hospital between 1993 and 2019 were enrolled in this study. Of these, 3222 patients underwent AS (AS group), whereas 2424 underwent IS (IS group). The patients were followed up regularly, at least once per year. Descriptive outcome data were presented according to the treatment group.

RESULTS

In the AS group, 124 patients (3.8%) had tumor enlargement of ≥3 mm, and the 10- and 20-year enlargement rates were 4.7% and 6.6%, respectively. Novel lymph node metastases occurred in 27 patients (0.8%), and the 10- and 20-year nodal metastasis occurrence rates were 1.0% and 1.6%, respectively. In the IS group, 13 patients (0.5%) experienced lymph node recurrence postoperatively, and the 10- and 20-year nodal recurrence rates were 0.4% and 0.7%, respectively. Eighteen (1.4%) of the 1327 patients who underwent hemithyroidectomy experienced recurrence in the residual thyroid. The rate of lymph node metastasis was significantly higher in the AS group than in the IS group (1.1% vs. 0.4% and 1.7% vs. 0.7% at 10 and 20 years, respectively; p =0.009), but the differences were small. However, the proportion of patients who underwent one or more and two or more surgeries were significantly higher in the IS group than that in the AS group (100% vs. 12.3% and 1.07% vs. 0.09%, p<0.01). Distant metastatic recurrence was observed in one patient after AS and conversion surgery and another after IS; however, they were alive (18.4 years and 18.8 years after diagnosis, respectively). None of the patients in this study died of thyroid carcinoma.

CONCLUSIONS

Long-term oncological outcomes of patients with PTMC generally did not differ clinically significantly between those undergoing AS and IS. AS is a viable initial management option for patients with low-risk PTMC.

Investigation of optimal convolutional neural network conditions for thyroid ultrasound image analysis

Neural network models have been used to analyze thyroid ultrasound (US) images and stratify malignancy risk of the thyroid nodules. We investigated the optimal neural network condition for thyroid US image analysis. We compared scratch and transfer learning models, performed stress tests in 10% increments, and compared the performance of three threshold values. All validation results indicated superiority of the transfer learning model over the scratch model. Stress test indicated that training the algorithm using 3902 images (70%) resulted in a performance which was similar to the full dataset (5575). Threshold 0.3 yielded high sensitivity (1% false negative) and low specificity (72% false positive), while 0.7 gave low sensitivity (22% false negative) and high specificity (23% false positive). Here we showed that transfer learning was more effective than scratch learning in terms of area under curve, sensitivity, specificity and negative/positive predictive value, that about 3900 images were minimally required to demonstrate an acceptable performance, and that algorithm performance can be customized according to the population characteristics by adjusting threshold value.

Lipoadenoma of the parathyroid: characteristics of a rare cause of hyperparathyroidism

Parathyroid Lipoadenoma (PLA) contains abundant mature adipose tissue and is a rare cause of hyperparathyroidism. This study aimed to investigate the clinical features of PLA in nine patients with primary hyperparathyroidism, including two men and seven women, with ages ranging from 45-84 years (median 60 years). PLA accounted for 0.5% of all parathyroid tumors during the study period. One patient presented with anorexia due to hypercalcemia; however, the other eight patients were asymptomatic. The median preoperative serum intact-parathyroid hormone (iPTH) and calcium levels were 143 pg/mL (range, 102-378) and 10.8 mg/dL (range, 10.3-11.3), respectively. PLA was difficult to identify using ultrasonography (US) as it appears as a moderately hyperechoic nodule and is difficult to distinguish from the surrounding adipose tissues. Only 33% of the lesions (three out of nine lesions) were accurately identified. However, they could be distinctly differentiated from the surrounding tissue using computed tomography (CT). All PLAs were also detected using the sesta-methoxyisobutylisonitrile single-photon emission-computed tomography (SPECT). All the patients were treated by a single gland extirpation. The median size and weight of the PLA were 14 mm (range, 10-22) and 567 mg (range, 200-1,533), respectively. In conclusion, the clinical manifestations of PLA are similar to those of ordinal parathyroid adenomas, except for their unique US and CT images. PLA should be considered as a potential etiologic factor in cases of hyperparathyroidism when the lesions are demonstrated as hyperechoic nodules or unidentified by US but detected by CT or SPECT imaging.

Prognostic significance of patient age in papillary thyroid carcinoma with no high-risk features

Older age is recognized as a predictor of poor prognosis in papillary thyroid carcinoma (PTC) patients. However, young age is associated with disease progression of PTC measuring 1 cm or smaller in patients on active surveillance. In this study, we investigated the relationship between patient age and prognosis of PTC belonging to very low-, low-, and intermediate-risk groups based on the guidelines published by the Japan Association of Endocrine Surgery in 2018. We enrolled 4,870 PTC patients with no high-risk features and assigned each to one of three categories: very low risk (N = 1,161), low risk (N = 1,746), and intermediate risk (N = 1,963). In very low-risk patients, the local recurrence-free survival (RFS) rate of young patients (<55 years) was significantly worse (p = 0.0437) than that of older patients (≥55 years). In low-risk patients, although age did not affect local recurrence, older patients were more likely to show distant recurrence on univariate (p = 0.0005) and multivariate analyses (p = 0.0017). In the intermediate-risk series, the local RFS rate of older patients tended to be poor (p = 0.0538), and older age was significantly associated with distant RFS (univariate, p = 0.0356; multivariate, p = 0.0439) and carcinoma death (univariate, p < 0.0001; multivariate, not done because of no other suitable factors). The prognostic significance of patient age depends on risk classification: younger age significantly predicts local recurrence in very low-risk PTC, while older age predicts worse prognosis in low- and intermediate-risk patients. These findings indicate that young age is related to rapid growth in early-phase PTC.

Prognostic factors for follicular thyroid carcinoma: the importance of vascular invasion

The World Health Organization (WHO) classifies follicular thyroid carcinoma (FTC) into three categories: minimally invasive (mFTC), encapsulated angioinvasive (eaFTC), and widely invasive (wFTC). This study investigated whether this classification is appropriate. We enrolled 523 patients who underwent initial surgery at Kuma Hospital between 1998 and 2015 and were diagnosed with FTC. Capsular invasion (CI) was classified as none, minimal (microscopic), or wide (macroscopic) invasion. Vascular invasion (VI) was divided according to the number of invasive foci into three degrees: VI(-), VI(1+), and VI(2+). For 507 M0 patients, age ≥55 years (p = 0.004), non-oxyphilic histology (p = 0.043), and male sex (p < 0.001) predicted poor distant recurrence-free survival (DR-FS) on univariate analysis; however, tumor size >4 cm and wide CI did not. The DR-FS rates significantly decreased from VI(-) to VI(2+) in a step-by-step fashion, including VI(-) vs. VI(1+) (p = 0.011) and VI(1+) vs. VI(2+) (p = 0.014). Multivariate analysis revealed that older age (p = 0.0004), non-oxyphilic histology (p = 0.041), male sex (p = 0.0052), VI(1+) (p = 0.017), and VI(2+) (p < 0.001) independently predicted distant recurrence. The DR-FS rates did not significantly differ among mFTC, wFTC/VI(-), and eaFTC/VI(1+). The DR-FS rate of eaFTC/VI(2+) was worse than that of eaFTC/VI(1+) (p = 0.042), but did not differ from that of wFTC/VI(1+/2+). Our findings suggest that subclassifying eaFTC according to the degree of VI and restricting wFTC to VI-positive cases would be better in the WHO classification. Revising the definition for wide CI is recommended.

Observational management of papillary microcarcinoma appearing in the remnant thyroid after hemithyroidectomy

Active surveillance for papillary thyroid microcarcinomas (PTMCs) initiated in Japan is becoming adopted worldwide as a management option. However, it remains unclear how to manage newly appearing PTMCs in the remnant thyroid after hemithyroidectomy. We investigated the outcomes of similar observational management (OM) for PTMCs appearing in the remnant thyroid after hemithyroidectomy for papillary thyroid carcinoma (PTC) and benign thyroid nodules. Eighty-three patients were newly diagnosed with PTMC in the remnant thyroid between January 1998 and March 2017. Of these, 42 patients underwent OM with >3 times ultrasound examinations. Their initial diagnoses were PTC (initially malignant group) in 37 patients and benign nodule (initially benign group) in 5 patients. We calculated the tumor volume doubling rate (TV-DR) during OM for each PTMC. The TV-DR (/year) was <-0.1, -0.1-0.1, 0.1-0.5, and >0.5 in 12, 19, 5, and 6 patients, respectively. The TV-DRs in both groups did not statistically differ, but six patients (16%) in the initially malignant group showed moderate growth (TV-DR >0.5/year). They underwent conversion surgery and none of them had further recurrence. The remaining 36 patients retained OM without disease progression. The TV-DR in the initially malignant group was not significantly associated with patients' backgrounds or their initial clinicopathological features. None of the patients in this study showed distant metastases/recurrences or died of thyroid carcinoma. Although a portion of PTMCs appearing after hemithyroidectomy for thyroid malignancy are moderately progressive, OM may be acceptable as a management option for PTMCs appearing in the remnant thyroid after hemithyroidectomy.

Metastatic papillary thyroid carcinoma presenting with elevated serum levels of carbohydrate antigen 19-9 (CA19-9): a case report

BACKGROUND

The major sites of distant metastases of papillary thyroid carcinoma (PTC) are the lung and bone; metastasis to the liver is rare. Although the postoperative serum thyroglobulin (Tg) level after total thyroidectomy is a good prognostic indicator for PTC when anti-thyroglobulin antibody (TgAb) is negative, the presence of TgAb interferes with the Tg assay, making serum Tg levels unreliable. Here we report a case of liver metastasis of PTC that presented with elevated serum levels of carbohydrate antigen 19-9 (CA19-9), which is usually a serum marker of pancreatic and gastrointestinal neoplasias.

CASE PRESENTATION

A 69-year-old man was diagnosed with PTC and underwent total thyroidectomy 16 years ago. The patient's serum Tg levels increased progressively during follow-up and his serum TgAb was negative. Positron emission tomography (PET) and computed tomography (CT) revealed metastases of the lung, cervical spine, mediastinum and liver. The liver lesion was a solitary tumor measuring 4.0 cm in the greatest dimension. His serum CA19-9 level was very high (326 U/mL), and intrahepatic cholangiocarcinoma was suspected from the results of various examinations including gastrointestinal endoscopic imaging and CT. Laparoscopic partial liver resection for segment 4 was performed. The histopathological diagnosis was a metastatic liver tumor from PTC. The immunohistological examination revealed that the liver tumor was positive for CA19-9 and Tg. The primary PTC, recovered from paraffin-embedded specimen, was also positive for CA19-9. After the surgery, his serum CA19-9 level as well as serum Tg level markedly decreased.

CONCLUSIONS

We presented the first reported case of liver metastasis of a PTC presenting with elevated serum levels of CA19-9 after total thyroidectomy. This case suggests that the serum CA19-9 levels may serve as a surrogate marker for PTC in place of the serum Tg level in patients with positive serum TgAb if the PTC and/or the metastatic lesions are positive for CA19-9 staining.

Intraoperative Management of the Recurrent Laryngeal Nerve Transected or Invaded by Thyroid Cancer

Thyroid cancer often invades the recurrent laryngeal nerve (RLN), causing vocal cord paralysis. In such patients, the invaded portion of the RLN usually needs to be resected through curative surgery. We attempt to preserve the nerve by performing sharp dissection in such cases. During nerve dissection, an intraoperative nerve monitoring system helps identify the course of the RLN in the fibrous tissue around the tumor or even within the tumor, and also helps evaluate the nerve integrity. Because of extensive dissection, the preserved RLN may become much thinner than its original thickness. We refer to this procedure as "partial layer resection" of the RLN. In our cases, although the dissected RLNs became thinner, we found that vocal cord function recovered in most patients. If the RLN is fully involved by thyroid cancer or response of the vocal cord against electric stimulation to the RLN is lost, we resect the portion of the RLN together with the tumor and repair it using one of the reconstruction techniques. When a unilateral RLN is resected, the vocal cord on that side is paralyzed. Symptoms include hoarseness, mis-swallowing, and short phonation. RLN reconstruction using one of the reconstruction techniques leads to the recovery of phonatory and swallowing function, although the normal motion of the vocal cord on the side of the anastomosis is not restored. We used direct anastomosis, free nerve grafting, ansa cervicalis-RLN anastomosis, and vagus-RLN anastomosis to reconstruct the RLN. Thyroid cancer often invades the RLN near the Berry's ligament. In such patients, surgeons might assume that reconstruction of the RLN may not be possible because the peripheral stump of the RLN cannot be observed. However, if we divide the inferior pharyngeal constrictor muscles along the lateral edge of the thyroid cartilage, the peripheral RLN can be identified, and nerve reconstruction can be performed. We refer to this procedure as "laryngeal approach".In summary, of the patients with thyroid cancer who required resection of the RLN, RLN reconstruction led to the recovery of phonatory function. We suggest that all thyroid surgeons familiarize themselves with these reconstruction techniques.

Long-term outcomes of cytologically benign thyroid tumors: a retrospective analysis of 3,102 patients at a single institution

Some thyroid tumors that are cytologically diagnosed as benign may be pathologically diagnosed as malignant. Here, we investigated the long-term outcomes of patients with thyroid tumors with benign cytology, and the factors for malignancy. We retrospectively reviewed the cases of 3,102 patients with thyroid tumors >1 cm cytologically diagnosed as benign at our hospital during a 1-year period from January 2007. The median follow-up duration for all patients was 68.7 (range 0.0-168.7) months. Immediate surgery and delayed surgery were performed in 393 and 148 patients, respectively. Eventually, 541 (17.4%) of the 3,102 patients underwent a thyroidectomy, and 2,561 (82.6%) were observed without surgery. Among the surgically treated patients, the tumors of 525 (97.0%) and 16 (3.0%) were pathologically diagnosed as benign and malignant, respectively. There was no significant difference in age, gender, tumor size, serum thyroglobulin level at surgery, or the tumor volume-doubling rate (TV-DR) between the benign and malignant cases. Only the ultrasonographic findings based on our hospital's classification system were directly and significantly linked to pathological diagnosis (p < 0.01). Among the tumors of the 667 patients who were followed without surgery for >10 years, 89.9% remained unchanged and 7.2% were reduced in size. Ultrasonographic evaluation provides important information for therapeutic decision-making regarding surgery versus observation for cytologically benign tumors.

Evaluation of the diagnostic utility of the aminotransferase/lactate dehydrogenase ratio for the suspension of tissue specimens during thyroid surgery for the identification of parathyroid tissue

Identification of the parathyroid glands during surgery is crucial for preventing postoperative hypoparathyroidism. Kikumori et al. reported that the aspartate aminotransferase (AST)/lactate dehydrogenase (LDH) ratio for the saline suspension of a suspicious tissue can differentiate parathyroid tissue from other tissues. The aim of this study was to evaluate the utility of this method and investigate the appropriate time for measurement. We obtained 465 tissue specimens during thyroidectomy of 102 patients with papillary thyroid carcinoma (PTC), and 422 specimens (129 parathyroid, 92 PTC, and 201 other tissues) with measurable AST and LDH were analyzed. Small pieces of the tissues were immersed in saline and sent for measurement of AST and LDH. The assay was performed immediately after thyroidectomy for 245 specimens (the same-day group) and during the next morning for the remaining 177 specimens (the next-day group). The accuracy of diagnosing parathyroid tissue was significantly better in the same-day group than in the next-day group. A cut-off value of 0.18 gave the best diagnostic precision, with an area under the receiver operating characteristic curve of 0.95 and 88.7% sensitivity and specificity in the same-day group. When the cut-off value was set to 0.20, the specificity for excluding carcinomatous tissues was 100%. When measured on the day of the surgery, the AST/LDH ratio for the saline suspension of the surgical specimens is useful for discriminating parathyroid tissues from other tissues. This method can be utilized at most hospitals where intraoperative frozen sections or rapid parathyroid hormone assays are not available.

Prognostic significance of vascular invasion and cell-proliferation activity in widely invasive follicular carcinoma of the thyroid

Widely invasive follicular thyroid carcinoma (wi-FTC) is regarded as having an aggressive character and a dire prognosis, but it has not been known whether all wi-FTCs have a dire prognosis. Herein we retrospectively analyzed the cases of 133 patients with wi-FTCs to determine the prognostic significance of vascular invasion and cell-proliferation activity based on the Ki-67 labeling index (LI). Of the 119 patients without distant metastasis (M0), 11 (9.2%) showed recurrence during the postoperative follow-up. In a univariate analysis, the recurrence-free survival (RFS) rates of the M0 patients with vascular invasion and those with a Ki-67 LI ≥5% were significantly poorer (p = 0.0013 and p = 0.0268, respectively) than those of the patients without vascular invasion or with a Ki-67 LI <5%. Other clinicopathological factors such as patient age, gender, tumor size, and oxyphilic tumor were not significantly related to the patients' RFS. In a multivariate analysis, positive vascular invasion independently affected the RFS (p = 0.0133), but Ki-67 >5% did not (p = 0.1348). To date, only five patients have died of their thyroid carcinoma; four cases were M1. In conclusion, although M0 wi-FTC generally has a favorable prognosis, cases with positive vascular invasion or a high Ki-67 LI are likely to recur, and careful postoperative follow-up is necessary.

Outcomes of endoscopic chemo- and laser-cauterizations and open fistulectomy for pyriform sinus fistula

Background

Acute suppurative thyroiditis through the congenital pyriform sinus fistula (PSF) often recurs if the fistula is not resected. Although endoscopic chemo-cauterization (ECC) to obliterate the orifice of the fistula is less invasive than open fistulectomy, it may require repeated treatments. We recently adopted an endoscopic diode laser-cauterization (ELC) system with the intention of improving treatment outcomes in PSF. Here, we describe ELC and compare the outcomes of these three modalities.

Methods

We evaluated 83 patients with PSF who underwent treatment between 2007 and 2018 at Kuma Hospital, a tertiary thyroid treatment hospital. ECC and ELC were implemented in 2007 and 2015, respectively. Patients who were ineligible for the endoscopic procedures underwent open fistulectomy. Barium swallow studies and computed tomography scan under a trumpet maneuver were performed after treatment to evaluate obliteration or removal of the fistula.

Results

In total, 70 of the 81 (86%) patients who underwent barium swallow studies after the first treatment achieved obliteration or removal of the fistula. The success rates for open fistulectomy, ECC, and ELC were 100% (9/9), 83% (49/59), and 100% (13/13), respectively. ECC and ELC had significantly shorter operative times and lower blood loss than open fistulectomy. Insufficient opening of the mouth was the major reason for converting endoscopic procedures to open fistulectomy.

Conclusions

ELC may yield superior outcomes and is therefore the optimal treatment modality for PSF. However, it is still associated with certain limitations. Thus, treatment selection remains dependent on the shape and size of the PSF and the mouth opening of the individual patient.

Graphical Abstract

Sorafenib and Lenvatinib Treatment for Metastasis/Recurrence of Radioactive Iodine-refractory Differentiated Thyroid Carcinoma

BACKGROUND/AIM

Radioactive iodine-refractory differentiated thyroid carcinoma (RR-DTC) has been treated with multi-kinase inhibitors (MKIs), e.g., sorafenib (SOR) and lenvatinib (LEN). We analyzed the outcomes of RR-DTC patients who underwent SOR or LEN treatment at Kuma Hospital.

PATIENTS AND METHODS

We enrolled 21 and 18 patients treated with SOR and LEN, respectively.

RESULTS

The incidence of partial response in the LEN group was significantly higher than that in the SOR group. Serum thyroglobulin significantly decreased from the beginning of treatment to 1 month later in the LEN group (not in the SOR group). The neutrophil-lymphocyte ratio (NLR) was significantly decreased at 1 month later in both groups. An NLR ≥3 at the start of MKI treatment had a prognostic impact.

CONCLUSION

For RR-DTC, LEN could be more effective than SOR, at least in the short term. The first-line drug should be selected based on other factors (e.g., adverse events, patient background).

Federated Learning for Thyroid Ultrasound Image Analysis to Protect Personal Information: Validation Study in a Real Health Care Environment

Background

Federated learning is a decentralized approach to machine learning; it is a training strategy that overcomes medical data privacy regulations and generalizes deep learning algorithms. Federated learning mitigates many systemic privacy risks by sharing only the model and parameters for training, without the need to export existing medical data sets. In this study, we performed ultrasound image analysis using federated learning to predict whether thyroid nodules were benign or malignant.

Objective

The goal of this study was to evaluate whether the performance of federated learning was comparable with that of conventional deep learning.

Methods

A total of 8457 (5375 malignant, 3082 benign) ultrasound images were collected from 6 institutions and used for federated learning and conventional deep learning. Five deep learning networks (VGG19, ResNet50, ResNext50, SE-ResNet50, and SE-ResNext50) were used. Using stratified random sampling, we selected 20% (1075 malignant, 616 benign) of the total images for internal validation. For external validation, we used 100 ultrasound images (50 malignant, 50 benign) from another institution.

Results

For internal validation, the area under the receiver operating characteristic (AUROC) curve for federated learning was between 78.88% and 87.56%, and the AUROC for conventional deep learning was between 82.61% and 91.57%. For external validation, the AUROC for federated learning was between 75.20% and 86.72%, and the AUROC curve for conventional deep learning was between 73.04% and 91.04%.

Conclusions

We demonstrated that the performance of federated learning using decentralized data was comparable to that of conventional deep learning using pooled data. Federated learning might be potentially useful for analyzing medical images while protecting patients’ personal information.

Marked Decrease Over Time in Conversion Surgery After Active Surveillance of Low-Risk Papillary Thyroid Microcarcinoma

Background: Active surveillance for low-risk papillary microcarcinoma (PMC) of the thyroid is an accepted and safe management strategy. However, some patients undergo conversion surgery after the initiation of active surveillance for various reasons. We investigated the reasons for conversion surgery and whether and how they changed over time. Methods: We enrolled 2288 patients with PMC who underwent active surveillance. Of these, 162 (7.1%) underwent conversion surgery >12 months after initiating active surveillance due to disease progression (57 patients), patient preference (43 patients), physician preference (31 patients), other associated thyroid or parathyroid diseases (24 patients), and other reasons (7 patients). We analyzed cumulative conversion rates not only in the whole cohort but also in the first three major subsets based on the reasons for surgery. We also divided our whole cohort into two groups based on the period of active surveillance commencement: the first-half group (February 2005-November 2011; 561 patients) and the second-half group (December 2011-June 2017; 1727 patients). Results: The criteria for PMC progression did not differ between the first- and second-half groups. The proportion of female patients in the physician preference group was significantly higher than that in the disease progression and the patient preference groups. Tumor size at surgery was larger, and tumor volume-doubling rate was higher in the disease progression group than in the other two groups. Patients in the second-half group were significantly less likely to undergo conversion surgery than those in the first-half group. Furthermore, conversion surgery rates in the second-half group were significantly lower than those in the first-half group in the patient preference, physician preference, and disease progression groups. Conclusions: Patients with PMC in the second-half group were significantly less likely to undergo conversion surgery than those in the first-half group regardless of the reason. This is probably because data accumulation of favorable outcomes with active surveillance significantly contributed to physicians' confidence and patients' trust and understanding of this disease.

Kinetic analysis of the growth rate of sporadic and hereditary medullary thyroid carcinoma: comparing the postoperative calcitonin-doubling rate with the hypothetical preoperative tumor volume-doubling rate

Background

Our previous kinetic analyses of changes in the tumor volume (TV) of papillary thyroid microcarcinomas during active surveillance revealed that the tumors’ growth varied over time from rather rapid growth to shrinkage and that the hypothetical TV-doubling rates (DRs) before the patients’ presentation were much larger than their observed TV-DRs, indicating that rapid growth phases preceded their presentation. Whether this phenomenon also occurs in medullary thyroid carcinoma (MTC) was unknown.

Methods

We retrospectively analyzed the cases of 46 MTC patients (18 hereditary, 28 sporadic; 9–80 years old at surgery, median 53.5 years; 19 males and 27 females) with elevated postoperative calcitonin (Ct) measured with the electrochemiluminescence immunoassay suggesting persistent disease. We calculated each patient’s Ct-DR and his/her hypothetical TV-DR, using the tumor size and age at surgery.

Results

Ct-DRs (/year) after surgery were > 0.5, 0.1–0.5, − 0.1–0.1, and < − 0.1 in 9, 21, 12, and 4 patients, respectively (median 0.17). The hypothetical TV-DRs (/year) before surgery were > 1, 0.5–1.0, 0.1–0.5 and < 0.1 in 11, 21, 14, and 0 patients, respectively (median 0.60). The hypothetical TV-DR was higher than the observed Ct-DR in 41 of the 46 MTC patients and all 18 patients with hereditary MTC, suggesting that a rapid growth phase preceded surgery in these patients.

Conclusions

In this series of MTC patients, the pre-surgery calculated hypothetical TV-DRs were significantly higher than the Ct-DRs observed post-surgery, suggesting that there were rapid growth periods before surgery in the vast majority of these MTC patients.

Thyroid Tubercle of Zuckerkandl May Not Arise from the Ultimobranchial Body: Results from Histological Analysis

Thyroid tubercle of Zuckerkandl (TZ) is a nodule arising from the posterolateral thyroid, considered to be a remnant of the ultimobranchial body (UB). Considering that C cells and solid cell nests also arise from the UB, we hypothesized that these would be present in the TZ. We examined the presence of C cells and solid cell nests in the TZ using the histological analyses of 21 patients with grade 2 or 3 TZs following Pelizzo's grading system. Out of 21 TZs, 19 (90.5%) were located in the right lobe of the thyroid. Microscopically, solid cell nests were found within the TZ in 1 case (4.8%), and within the main thyroid tissues in 3 cases (14.3%). Calcitonin-positive C cells were scattered within the TZ in 1 case (4.8%), and within the main thyroid tissue in 15 cases (71.4%). The distribution of C cells within the main thyroid tissue was denser than that within the TZ. The above-mentioned results indicated the lack of C cells and solid cell nests in the TZ. Although the TZ may have an embryological origin different from that of ordinary thyroid tissue, it is unlikely that the remnants of the UB are involved in the formation of the TZ.

Subset analysis of the Japanese risk classification guidelines for papillary thyroid carcinoma

Guidelines published by the Japan Association of Endocrine Surgeons (JAES)/Japanese Society of Thyroid Surgery (JSTS) for patients with papillary thyroid carcinoma describe four risk classes (very low-, low-, intermediate- and high-risk) for deciding on therapeutic strategies. Here, we investigate cause-specific survival (CSS) of high- and intermediate-risk patients, taking their age into consideration. CSS of intermediate-risk patients ≥55 years was poorer than that of those <55 years (p < 0.0001) (20-year CSS rates, 96.9% vs. 98.7%). CSS of intermediate-risk patients <55 years was excellent but still poorer (p = 0.0152) than that of low- or very low-risk patients (20-year CSS rates, 100%). CSS of high-risk patients <55 years (20-year CSS rates, 96.0%) was similar (p = 0.7412) to that of intermediate-risk patients ≥55 years, while high-risk patients ≥55 years (20-year CSS rates, 80.6%) showed much poorer prognosis (p < 0.0001) than the others. In high-risk patients <55 years, distant metastasis (M1), extrathyroid extension (Ex), node metastasis ≥3 cm, and extranodal tumor extension, and in those ≥55 years, M1, Ex, and tumor size >4 cm were regarded as prognostic factors on multivariate analysis. We therefore conclude that 1) prognosis of high-risk patients ≥55 years should be carefully treated because of significantly poor prognosis, 2) prognostic factors of high-risk patients vary according to patient age, and 3) overtreatment of intermediate-risk patients and young high-risk patients should be avoided; however, appropriate treatment strategies need to be established, considering that their prognoses are excellent, but still poorer than low- or very low-risk patients.

Kinetic Analysis of Growth Activity in Enlarging Papillary Thyroid Microcarcinomas

Background: Although papillary thyroid microcarcinoma (PMC) is generally stable on active surveillance, conversion surgery is recommended for enlarging tumors. However, it remains unclear which enlargement threshold should be considered sufficient to trigger surgery. This study analyzed changes in the growth activity of PMC, before and after enlargement. Methods: We enrolled 824 patients with PMC, in whom active surveillance was initiated between 2005 and 2011 (median duration of follow-up: 6.04 years). Changes in the maximal tumor size and tumor volume were evaluated. Point of enlargement (PE) was defined as the time at which maximal tumor size or tumor volume had increased by ≥3 mm (PE-M) or by ≥50% (PE-V), respectively. In patients with PMC who underwent at least three ultrasound examinations during the study period, we compared the tumor doubling rates (TDRs, designated as the inverse of doubling time) between pre- and post-PEs. Results: Ten-year enlargement-free survival rates based on maximal tumor size and tumor volume were 86.9% and 54.9%, respectively. The median post-PE TDRs was significantly lower than that of pre-PEs (-0.091/year vs. 0.509/year [p < 0.001] for PE-M, and -0.058/year vs. 0.370/year [p < 0.001] for PE-V), indicating decreased tumor growth after PEs. After PE-M and PE-V, the PMCs continued to rapidly enlarge (TDR >0.5/year) in only 6 (7.7%) and 11 (3.8%) patients and moderately enlarge (TDR 0.1-0.5/year) in 10 (12.8%) and 35 (12.1%) patients, respectively. Conversely, tumors shrank (TDR < -0.1/year) in 37 (47.4%) and 105 (36.1%) patients, respectively, and remained stable (TDR ranged between 0.1/year and -0.1/year) in 25 (32.1%) and 140 (48.1%) patients, respectively. Conclusion: Since most PMCs demonstrate a significant decrease in growth activity after enlargement, performing surgery immediately after the PE may be premature.

Prognostic Value of Extranodal Tumor Extension in Papillary Thyroid Carcinoma: Proposal for Upstaging of Cases with Extranodal Tumor Extension

BACKGROUND

Recently, we have created a revised version of the eighth edition of the tumor-node-metastasis classification for papillary thyroid carcinomas (PTCs) by subdividing the T4a (T4a1 [moderate] and T4a2 [significant]) and N (N1 [N ≤ 3 cm] and N2 [N > 3 cm]) classifications. This re-staging better stratified patient outcomes. In this study, we investigated the prognostic significance of extranodal tumor extension (LNEx) in PTC.

METHODS

Five thousand six hundred and eighty-three patients with PTC surgically treated in Kuma Hospital were enrolled. We evaluated LNEx based on intraoperative findings.

RESULTS

One hundred and twenty-seven patients (2%) displayed LNEx. In contrast to what we observed for extrathyroid extension, the prognostic value of LNEx did not change based on the organ that had been invaded, and we therefore analyzed LNEx patients as a single group. In patients aged 55 or older, LNEx independently affected patients' prognoses, as did T4a2 and N2. The cancer-specific survival (CSS) of patients in Stage I but having LNEx demonstrated the similar prognosis to patients in Stage II. Further, in the subset analysis for Stage II patients aged 55 or older, LNEx had a significant prognostic value for CSS in both the univariate and multivariate analyses, as did N2. The CSS of Stage II patients aged 55 or older with LNEx did not differ from that of Stage III patients.

CONCLUSIONS

It is appropriate that, similar to T4a2 or N2 patients, LNEx-positive patients younger than 55 years in Stage I and those aged 55 or older in Stage II are re-staged to II and III, respectively.

Ultrasound image analysis using deep learning algorithm for the diagnosis of thyroid nodules

Fine needle aspiration (FNA) is the procedure of choice for evaluating thyroid nodules. It is indicated for nodules >2 cm, even in cases of very low suspicion of malignancy. FNA has associated risks and expenses. In this study, we developed an image analysis model using a deep learning algorithm and evaluated if the algorithm could predict thyroid nodules with benign FNA results.Ultrasonographic images of thyroid nodules with cytologic or histologic results were retrospectively collected. For algorithm training, 1358 (670 benign, 688 malignant) thyroid nodule images were input into the Inception-V3 network model. The model was pretrained to classify nodules as benign or malignant using the ImageNet database. The diagnostic performance of the algorithm was tested with the prospectively collected internal (n = 55) and external test sets (n = 100).For the internal test set, 20 of the 21 FNA malignant nodules were correctly classified as malignant by the algorithm (sensitivity, 95.2%); and of the 22 nodules algorithm classified as benign, 21 were FNA benign (negative predictive value [NPV], 95.5%). For the external test set, 47 of the 50 FNA malignant nodules were correctly classified by the algorithm (sensitivity, 94.0%); and of the 31 nodules the algorithm classified as benign, 28 were FNA benign (NPV, 90.3%).The sensitivity and NPV of the deep learning algorithm shown in this study are promising. Artificial intelligence may assist clinicians to recognize nodules that are likely to be benign and avoid unnecessary FNA.

Appropriateness of the revised Japanese guidelines' risk classification for the prognosis of papillary thyroid carcinoma: a retrospective analysis of 5,845 papillary thyroid carcinoma patients

The revised Japan Association of Endocrine Surgeons (JAES)/Japanese Society of Thyroid Surgery (JSTS) guidelines for patients with papillary thyroid carcinoma (PTC) describe four risk classes: very-low-risk, low-risk, intermediate-risk, and high-risk. Here we conducted a retrospective analysis to evaluate the appropriateness of these guidelines' risk classification of PTCs. Lymph node recurrence-free, distant recurrence-free and cause-specific survivals at 15-year of high-risk group were significantly poorer than those at 15-year of intermediate-group and these survivals of intermediate-group were poorer than of low- or very-low-risk patients. In the subset analyses based on patient age (≥55 years and <55 years), we obtained the same results in both subsets. Age significantly worsen the whole prognosis of high-risk patients and cause-specific survival of intermediate-risk patients, but not the prognosis of low- or very-low-risk patients. Therefore, the risk classification of the revised JAES/JSTS guidelines is appropriate, and therapeutic strategies should be decided based on the risk class together with the patients' age.

Thrombotic Microangiopathy with Severe Proteinuria Induced by Lenvatinib for Radioactive Iodine-Refractory Papillary Thyroid Carcinoma

Standard therapy for radioactive iodine (RAI)-refractory differentiated thyroid cancer (DTC) is multi-targeted kinase inhibitors (m-TKIs), represented by sorafenib and lenvatinib. One of the main target molecules of m-TKIs is vascular endothelial growth factor receptor (VEGF-R). m-TKIs are known to cause adverse reactions such as hypertension and proteinuria as a class effect. In particular, proteinuria is thought to result from vascular endothelial damage and podocytopathy in glomeruli, and the development of thrombotic microangiopathy (TMA) has been reported for VEGF inhibitors. We encountered a patient with RAI-refractory (RR) papillary thyroid carcinoma (PTC) who developed proteinuria and renal dysfunction due to lenvatinib. Renal biopsy demonstrated that these changes were caused by TMA. To our knowledge, this is the first reported case of TMA due to lenvatinib in a Japanese patient with RR-PTC. A 70-year-old woman developed proteinuria, renal impairment and hypertension while receiving lenvatinib for RR-PTC. Her proteinuria and renal damage continued to worsen despite dose reductions and dose interruptions. Renal biopsy was consistent with the chronic type of TMA. These findings indicate that TMA is a possible cause of proteinuria due to lenvatinib, as has been reported for the VEGF inhibitors.

Natural history of papillary thyroid microcarcinoma: Kinetic analyses on tumor volume during active surveillance and before presentation

BACKGROUND

We report on the growth of papillary microcarcinoma during active surveillance and before clinical presentation.

METHODS

We conducted a retrospective study of 169 patients with papillary microcarcinoma who were enrolled in active surveillance at our hospital between 2000 and 2004. Patients were followed for a median of 10.1 years using serial ultrasonography (median, 12 examinations), used to calculate the tumor doubling time. To contextualize tumor growth rates during active surveillance, we calculated the hypothetical tumor doubling time before clinical presentation. To resolve the limitations in tumor doubling time, tumor doubling rates were inversely transformed into doubling rates.

RESULTS

The doubling rates (per year) during active surveillance (median: 0.0) were >0.5, 0.1 to 0.5, -0.1 to 0.1, and <-0.1 in 5, 38, 97, and 29 cases, respectively. The proportions of tumors with rather rapid growth, slow growth, stable, and a decrease in size were 3%, 22%, 57%, and 17%, respectively.

CONCLUSION

Tumor growth of papillary microcarcinomas varies from rather rapid growth to a decrease in size during active surveillance.

Calcitonin measurement in fine-needle aspirate washout fluid by electrochemiluminescence immunoassay for thyroid tumors

Purpose

For the differential diagnosis of medullary thyroid carcinoma (MTC) on thyroid nodules, ultrasound-guided fine-needle aspiration cytology is a useful and safe procedure, but its diagnostic accuracy is not high enough. As an ancillary method to accurately diagnose MTC, the calcitonin in fine-needle aspirate washout fluid (FNA-Ct) is used. However, no data are available about cut-off values of FNA-Ct using the currently available electrochemiluminescence immunoassay (ECLIA).

Methods

We investigated 180 thyroid nodules in 141 patients. After smearing, the syringe and needle used for the FNA were rinsed with normal saline (0.5 mL). The calcitonin in the washout was measured by ECLIA.

Results

The FNA-Ct in the non-MTC nodules of MTC patients, non-MTC nodules of non-MTC patients, and MTC nodules were 10.6-2100 pg/mL (median 24.6 pg/mL), < 0.5-21.0 pg/mL (median < 0.5 pg/mL), and 94.9-4,070,000 pg/mL (median 177,000 pg/mL), respectively. A receiver operating characteristic analysis of the MTC nodules and the non-MTC nodules of the non-MTC patients indicated that the cut-off value was 21.0 pg/mL, leading to 100% sensitivity and 100% specificity.

Conclusions

This is the first study to determine the cut-off value of FNA-Ct with an ECLIA, and we propose that the optimal cut-off value is 21.0 pg/mL.

Excellent Prognosis of Central Lymph Node Recurrence-Free Survival for cN0M0 Papillary Thyroid Carcinoma Patients Who Underwent Routine Prophylactic Central Node Dissection

Introduction

In Japan, prophylactic central node dissection (p-CND) for papillary thyroid carcinoma (PTC) has been routinely performed in many institutions, including ours (Kuma Hospital, Japan). We evaluated the recurrence to a central lymph node in patients with cN0M0 PTC who underwent routine p-CND.

Materials and methods

We enrolled 4301 patients with cN0M0 PTC who underwent an initial surgery between 1987 and 2005 (median age 51 years). The postoperative follow-up periods ranged from 4 to 362 months (median 164 months). Only 15 patients underwent radioactive iodine (RAI) ablation (≥30 mCi) after total or near total thyroidectomy.

Results

Of the 4301 patients with N0M0 PTC who underwent p-CND, 2548 (59%) were diagnosed as pN1a on postoperative pathological examination. To date, only 52 cases (1.2%) showed recurrence to a central lymph node. The 10-year and 20-year central node recurrence-free survival rates were excellent at 99.1 and 98.2%, respectively. On multivariate analysis, age ≥55 years, significant extrathyroid extension, tumor size >2 cm, and ≥5 pathologically confirmed central node metastases (but not the presence of central node metastasis) independently affected central node recurrence.

Conclusions

Under the situation of routine p-CND, the central node recurrence-free survival of cN0M0 PTC is excellent. However, future studies, including double-arm studies from Japan, should examine whether the omission of p-CND cN0M0 PTC is appropriate without RAI ablation in consideration of various factors, including the pros and cons of p-CND.

Prognostic value of the 8th edition of the tumor-node-metastasis classification for patients with papillary thyroid carcinoma: a single-institution study at a high-volume center in Japan

The tumor-node-metastasis (TNM) staging system is most commonly adopted to evaluate the prognosis of patients with thyroid carcinoma. The 8^th edition of the TNM staging system, an extensively revised version of the 7^th edition, was recently released. We aimed to investigate whether and how well the 8^th edition reflects the cause-specific survival (CSS) of patients with papillary thyroid carcinoma by analyzing the cases in 5,892 patients who underwent initial surgery at Kuma Hospital between 1987 and 2005. The median postoperative follow-up duration was 178 months (range: 6-357 months). One patient with T4b disease was excluded from the analysis. Overall, 116 (2.0%) patients died of thyroid carcinoma. The proportion of variance explained (PVE) for CSS in the 7^th and 8^th editions was 10.69 and 10.97, respectively. Using the 7^th edition, CSS of patients with stage IVA and stage III disease was similar (p = 0.32). In contrast, using the 8^th edition, CSS was poorer in stage II than in stage I (p < 0.001), in stage III than in stage II (p < 0.001), and in stage IVB than in stage III (p < 0.001). Similar results were observed for disease-free survival. Although we could not establish any objective evidence that the 8^th edition is superior to the 7^th edition, the 8^th edition is simpler and more convenient, as it includes fewer stages and addresses the issue of the 7^th edition where stage IVA and III patients had similar prognoses.

Prognostic value of the 8th tumor-node-metastasis classification for follicular carcinoma and poorly differentiated carcinoma of the thyroid in Japan

Follicular thyroid carcinoma (FTC), a form of differentiated thyroid carcinoma, is the second most common malignancy arising from thyroid follicular cells. Recently, the tumor-node-metastasis (TNM) classification for differentiated thyroid carcinoma was revised from the 7^th to the 8^th edition. The diagnostic criteria for poorly differentiated carcinoma (PDC) were also updated in the latest World Health Organization (WHO) classification. In this study, we investigated whether these changes are appropriate for accurately predicting prognosis. Three hundred and twenty-nine patients diagnosed with postoperative pathologically confirmed FTC, who underwent initial surgery at our hospital between 1984 and 2004, were enrolled. For this study, patients were re-evaluated and diagnosed with FTC (N = 285) or PDC (N = 44) without typical nuclear findings of papillary thyroid carcinoma. For FTC, the 8^th TNM classification was a more accurate predictor of prognosis than the 7^th TNM classification. In the 8^th TNM classification, cause-specific survival became significantly poorer from Stage I to IVB. The cause-specific survival of PDC based on the latest WHO classification was worse than, but did not significantly differ from, that of PDC based only on the former WHO classification. For PDC, neither of the TNM classifications could accurately predict prognosis. Taken together, we conclude that (1) the 8^th TNM classification more accurately reflects the prognosis of FTC than the 7^th TNM classification; (2) PDC based on the former WHO classification should be retained, at least in Japan; and (3) the TNM classification may not be suitable for predicting the prognosis of PDC.

Calcifications in Thyroid Tumors on Ultrasonography: Calcification Types and Relationship with Histopathological Type

PURPOSE

The purpose of the study is to clarify the prevalence of calcifications within thyroid tumors on ultrasonography as well as the relationship between the calcification and histopathological types.

MATERIALS AND METHODS

Calcifications were classified into 6 (or 8) types according to their shape, size, and region. The prevalence of calcifications and types were investigated in new outpatients and patients who underwent thyroid surgery.

RESULTS

Among 2,902 nodules in 2,678 new outpatients, 747 nodules (26%) had calcifications. The types showed a wide distribution. Among 941 patients with papillary carcinoma (PC), 725 patients (77%) had calcifications, and the types showed a wide distribution. 18 patients with the diffuse sclerosing variant of PC only showed punctate microcalcifications in the parenchyma (100%), 32 patients with the cyst-forming type of PC mostly fragmentary and massive types (100%), and 161 metastatic lymph nodes from PC mostly punctate microcalcifications and fragmentary types (48%). Among 337 patients with follicular carcinoma, 79 patients (23%) had calcifications, and the types were mostly fragmentary, massive, and egg-shell types. Among 41 patients with undifferentiated carcinoma, 33 patients (80%) presented with calcifications, which were mostly the massive and egg-shell types. Among 137 patients with medullary carcinoma, 99 patients (72%) had calcification, and the types showed a wide distribution. None of 173 patients with primary thyroid lymphoma had calcifications (0%).

CONCLUSION

Calcifications on ultrasonography can be one of the characteristic findings and a full understanding of the prevalence of calcifications and types will markedly contribute to the ultrasonic diagnosis of thyroid tumors.

Trends in the Implementation of Active Surveillance for Low-Risk Papillary Thyroid Microcarcinomas at Kuma Hospital: Gradual Increase and Heterogeneity in the Acceptance of This New Management Option

BACKGROUND

Active surveillance (AS) of low-risk papillary thyroid microcarcinoma (PMC) was adopted as a management modality in both the Japanese guidelines in 2011 and the American Thyroid Association guidelines in 2015. AS was initiated at Kuma Hospital in 1993 but was not immediately accepted by all physicians. This study investigated the history of acceptance of AS at Kuma Hospital over time. The results should assist in the implementation of AS at other hospitals in Japan and other countries.

METHODS

This study included 4023 patients who were cytologically diagnosed with low-risk PMC at Kuma Hospital during the 24-year period between October 1993 and June 2016. The trend in the frequency of AS use over time was analyzed, dividing the 24-year study period into five parts based on the change in frequency of AS use: 1993-1997, 1998-2002, 2003-2006, 2007-2013, and 2014-2016.

RESULTS

The frequency of AS use in the present cohort was 65%. The frequency gradually increased from 30% in 1993-1997 to 88% in 2014-2016, with a slight decrease from 51% in 1998-2002 to 42% in 2003-2006. Until 2007, patients were mostly seen by surgeons, and the frequency of AS use varied remarkably among individual surgeons. Since 2007, the number of patients whose therapeutic strategies are determined by endocrinologists has increased, and the frequency of AS use for low-risk PMC by endocrinologists has been higher than that by surgeons.

CONCLUSIONS

At Kuma Hospital, acceptance of AS for low-risk PMC gradually increased over the 24-year study period, but AS was not equally accepted by all physicians. Such variations in the acceptance of AS among individual physicians are also expected to exist in other hospitals. However, due to increasing evidence of the safety and superiority of AS over immediate surgery for this indolent disease, it is expected that AS will gain faster acceptance in other hospitals in Japan and around the world.

Estimation of the lifetime probability of disease progression of papillary microcarcinoma of the thyroid during active surveillance

BACKGROUND

We reported that a minority of patients with low-risk papillary microcarcinoma of the thyroid showed disease progression during active surveillance and that older patients had significantly lower disease progression rates than younger patients. Here, we estimated lifetime (≤85 years old) probabilities of disease progression during active surveillance according to the age at presentation based on age decade-specific disease progression rates.

METHODS

From 1993-2013, 1,211 low-risk papillary microcarcinoma patients aged 20-79 years underwent active surveillance at Kuma Hospital. We calculated the disease progression rate at the 10-year point of active surveillance for each age-decade group (20s to 70s) with the Kaplan-Meier method. The lifetime disease progression probability for each age group was calculated as (1 - cumulative probability of progression-free survival calculated with age decade-specific disease progression rates) until the patients reached their 80s (i.e., 85 years on average).

RESULTS

The age decade-specific disease progression rates at 10 years of active surveillance were 36.9% (20s), 13.5% (30s), 14.5% (40s), 5.6% (50s), 6.6% (60s), and 3.5% (70s); the respective lifetime disease progression probabilities were 60.3%, 37.1%, 27.3%, 14.9%, 9.9% and 3.5% according to the age at presentation.

CONCLUSION

The estimated lifetime disease progression probabilities of papillary microcarcinoma during active surveillance vary greatly according to the age at presentation.

"Nodule in Nodule" on Thyroid Ultrasonography: Possibility of Follicular Carcinoma Transformed from Benign Thyroid Tumor

BACKGROUND

It is generally considered impossible to differentiate follicular carcinomas from follicular adenomas by means of ultrasonography or cytology before surgery. Therefore, follicular carcinoma is histopathologically diagnosed by verifying capsular and/or vascular invasion after surgery. However, ultrasonography may play an important role in diagnosing follicular carcinoma preoperatively in a small number of cases.

CASE DESCRIPTION

Four cases of follicular carcinoma or follicular neoplasm that transformed from a benign thyroid tumor and demonstrated a "nodule in nodule" appearance on ultrasonography are presented in this report. Characteristic ultrasound features of such patients are: (1) a "nodule in nodule" appearance, (2) a well-defined boundary line between the nodules, and (3) separate distribution of blood signals within each nodule.

CONCLUSION

A small number of patients with follicular carcinomas or follicular neoplasms may present with a "nodule in nodule" appearance on ultrasonography. It was suggested a long time ago that follicular carcinomas may develop from benign thyroid tumors. The fact that follicular carcinomas appear within benign tumors may be evidence of thyroid tumorigenesis.

Comparison of the costs of active surveillance and immediate surgery in the management of low-risk papillary microcarcinoma of the thyroid

The incidence of thyroid cancer is increasing rapidly in many countries, resulting in rising societal costs of the care of thyroid cancer. We reported that the active surveillance of low-risk papillary microcarcinoma had less unfavorable events than immediate surgery, while the oncological outcomes of these managements were similarly excellent. Here we calculated the medical costs of these two managements. We created a model of the flow of these managements, based on our previous study. The flow and costs include the step of diagnosis, surgery, prescription of medicine, recurrence, salvage surgery for recurrence, and care for 10 years after the diagnosis. The costs were calculated according to the typical clinical practices at Kuma Hospital performed under the Japanese Health Care Insurance System. If conversion surgeries were not considered, the 'simple cost' of active surveillance for 10 years was 167,780 yen/patient. If there were no recurrences, the 'simple cost' of immediate surgery was calculated as 794,770 yen/patient to 1,086,070 yen/patient, depending on the type of surgery and postoperative medication. The 'simple cost' of surgery was 4.7 to 6.5 times the 'simple cost' of surveillance. When conversion surgeries and recurrence were considered, the 'total cost' of active surveillance for 10 years became 225,695 yen/patient. When recurrence were considered, the 'total cost' of immediate surgery was 928,094 yen/patient, which was 4.1 times the 'total cost' of the active surveillance. At Kuma Hospital in Japan, the 10-year total cost of immediate surgery was 4.1 times expensive than active surveillance.

Diagnosis and surgical indications of oxyphilic follicular tumors in Japan: Surgical specimens and cytology

Oxyphilic cell carcinoma is a relatively rare type of differentiated thyroid carcinoma. We investigated the diagnosis of oxyphilic cell carcinoma based on surgical specimens and cytology to elucidate the indications for surgery for oxyphilic tumors. Among 330 patients pathologically diagnosed as having an oxyphilic cell carcinoma or adenoma, the incidence of carcinoma was 21%. The pathological diagnosis of oxyphilic cell carcinoma was related to tumor size (>4 cm). On cytology, 79% of the tumors were classified as category IV or greater by the Bethesda System for Reporting Thyroid Cytopathology (BSRTC), but no significant difference was established between category IV or greater and categories I-III regarding the incidence of carcinoma. Of 998 patients cytologically diagnosed as having oxyphilic cell tumors (BSRTC category IV), 426 underwent surgery and 66 (15%) were diagnosed as malignancies. In a univariate analysis, serum thyroglobulin (Tg) levels (>500 ng/dL) for anti-Tg antibody-negative patients, tumor size (>4 cm) and US class (≥3) significantly predicted malignant histology. A multivariate logistic analysis revealed that US finding was an independent predictor of malignant histology, and tumor size (>4 cm) also predicted malignancy when the Tg level was excluded from the variables. These findings suggest that, for thyroid tumors diagnosed as oxyphilic follicular neoplasms on cytology, surgical indications are tumors with US class ≥3, tumor size >4 cm, and Tg >500 ng/dL (with negative Tg-antibody). It is not appropriate to perform surgery for all cases for a precise histological classification, unlike the BSRTC recommendation.

Prognostic impact of Ki-67 labeling index in minimally invasive follicular thyroid carcinoma

We investigated the prognostic impact of the Ki-67 labeling index (LI) in minimally invasive follicular thyroid carcinoma (FTC). We enrolled 192 patients (including four with distant metastasis at diagnosis) who were pathologically diagnosed as having minimally invasive FTC between 1998 and 2007 at Kuma Hospital. When the Ki-67 LI was higher than 5% in the hot area, we regarded it as a high Ki-67 LI. In a univariate analysis, patient age (≥45 years), high-frequent vascular invasion (≥4 in H&E specimens), and high Ki-67 LI significantly predicted the disease-free survival (DFS) of the patients. Since none of the patients <45 years old showed a recurrence, we performed a multivariate analysis of variables other than patient age. In the multivariate analysis including the presence of vascular invasion, high Ki-67 LI was an independent predictor of carcinoma recurrence. However, in the multivariate analysis including high-frequent vascular invasion, only high-frequent vascular invasion independently affected the DFS. These findings suggest that the Ki-67 LI has a rather strong prognostic value for the DFS of patients, although its impact was less than those of patient age and high-frequent vascular invasion.

Right-sided aortic arch and aberrant left subclavian artery with or without a left nonrecurrent inferior laryngeal nerve

Background

In thyroid surgery, preserving the recurrent laryngeal nerve (RLN) is crucial for preventing postoperative phonatory dysfunction. Right nonrecurrent laryngeal nerves (NRLNs) are not particularly rare, and they are vulnerable to injury during surgery. This anomaly is associated with a right aberrant subclavian artery. Thus, a right‐sided aortic arch with an aberrant left subclavian artery (LSA) suggests a possible left NRLN.

Methods

We report the cases of 4 patients with right‐sided aortic arch and aberrant LSA. Preoperative imaging studies revealed those anomalies, but no signs of situs inversus. During the surgeries, only 1 of the 4 cases had a left NRLN. We retrospectively evaluated the patients' imaging studies.

Results

An aortic diverticulum was found at the point at which the aberrant LSA originated in the 3 patients with left‐RLNs, but not in the patient with the left‐NRLN.

Conclusion

In right‐sided aortic arch + aberrant LSA cases, the absence of an aortic diverticulum suggests a left NRLN. © 2016 Wiley Periodicals, Inc. Head Neck 38: First–E2511, 2016

Tumor protrusion with intensive blood signals on ultrasonography is a strongly suggestive finding of follicular thyroid carcinoma

AIM

It is difficult to differentiate follicular carcinomas (FC) from follicular adenomas (FA) because ultrasonography and cytology provide very similar findings. FC is histopathologically diagnosed to have capsular and/or vascular invasion. In a few patients, tumor protrusions are observed by preoperative ultrasonography as large forms of capsular invasion of follicular carcinomas. The aim of the study was to clarify the predictive value of tumor protrusions on preoperative ultrasonography for follicular carcinomas.

MATERIAL AND METHODS

A total of 531 patients (FC: 184 patients, FA: 347 patients) undergoing thyroid surgery were included in this study. A tumor protrusion on ultrasonography was defined as follows: 1) a solid tumor extending beyond a marginal line of capsular zone of the main tumor on B-mode ultrasonography; 2) intensive blood signals observed within the protrusion area on Doppler ultrasonography. The large form of capsular invasion was defined if the protrusion lesion was histopathologically diagnosed to be a capsular invasion of follicular carcinoma.

RESULTS

The sensitivity of tumor protrusion was 0.071, specificity 0.994, positive predictive value 0.867, and negative predictive value 0.669 for FC diagnosis. For the large form of capsular invasion in FC the sensitivity of tumor protrusion was 0.813, specificity 0.982, positive predictive value 0.684, and negative predictive value 0.982.

CONCLUSIONS

A tumor protrusion with intensive blood signals extending from the main tumor on ultrasonography strongly suggests a large form of capsular invasion of follicular carcinoma.

Incidences of Unfavorable Events in the Management of Low-Risk Papillary Microcarcinoma of the Thyroid by Active Surveillance Versus Immediate Surgery

BACKGROUND

The incidence of papillary microcarcinoma (PMC) of the thyroid is rapidly increasing globally, making the management of PMC an important clinical issue. Excellent oncological outcomes of active surveillance for low-risk PMC have been reported previously. Here, unfavorable events following active surveillance and surgical treatment for PMC were studied.

METHODS

From February 2005 to August 2013, 2153 patients were diagnosed with low-risk PMC. Of these, 1179 patients chose active surveillance and 974 patients chose immediate surgery. The oncological outcomes and the incidences of unfavorable events of these groups were analyzed.

RESULTS

In the active surveillance group, 94 patients underwent surgery for various reasons; tumor enlargement and the appearance of novel lymph node metastases were the reasons in 27 (2.3%) and six patients (0.5%), respectively. One of the patients with conversion to surgery had nodal recurrence, and five patients in the immediate surgery group had a recurrence in a cervical node or unresected thyroid lobe. All of these recurrences were successfully treated. None of the patients had distant metastases, and none died of the disease. The immediate surgery group had significantly higher incidences of transient vocal cord paralysis (VCP), transient hypoparathyroidism, and permanent hypoparathyroidism than the active-surveillance group did (4.1% vs. 0.6%, p < 0.0001; 16.7% vs. 2.8%, p < 0.0001; and 1.6% vs. 0.08%, p < 0.0001, respectively). Permanent VCP occurred only in two patients (0.2%) in the immediate surgery group. The proportion of patients on L-thyroxine for supplemental or thyrotropin (TSH)-suppressive purposes was significantly larger in the immediate surgery group than in the active surveillance group (66.1% vs. 20.7%, p < 0.0001). The immediate surgery group had significantly higher incidences of postsurgical hematoma and surgical scar in the neck compared with the active surveillance group (0.5% vs. 0%, p < 0.05; and 8.0% vs. 100%, p < 0.0001, respectively).

CONCLUSIONS

The oncological outcomes of the immediate surgery and active surveillance groups were similarly excellent, but the incidences of unfavorable events were definitely higher in the immediate surgery group. Thus, active surveillance is now recommended as the best choice for patients with low-risk PMC.

Effects of Pregnancy on Papillary Microcarcinomas of the Thyroid Re-Evaluated in the Entire Patient Series at Kuma Hospital

BACKGROUND

An active-surveillance clinical trial of low-risk papillary microcarcinoma (PMC) patients has been performed at the authors' institution, Kuma Hospital, since 1993. Favorable oncological results have been reported. During the trial, a few patients were encountered with PMC that showed enlargement during pregnancy, and these cases have been reported. During pregnancy, a large amount of human chorionic gonadotropin (hCG) having weak thyrotropin (TSH) activity is produced, possibly affecting the progression of PMC. This study investigated how pregnancy and delivery influenced the progression of PMC in the entire active surveillance PMC patient series.

METHODS

From 1993 to 2013, 1841 patients with low-risk PMC chose the active surveillance program. Fifty of the 1549 female PMC patients experienced 51 pregnancies/deliveries. To minimize observer variation, a single specialist sonographer re-evaluated the changes in the size of these 50 patients' PMCs before and after the pregnancies/deliveries.

RESULTS

Four patients (8%) showed enlargement of PMC by ≥3 mm; one patient (2%) showed a decrease by ≥3 mm, and the remaining 44 patients (45 events, 90%) showed stable disease. None of the patients had a novel appearance of lymph node metastases during pregnancy. Of the four patients with enlargement, two underwent surgery after delivery, and the other two continued the active surveillance, since their tumors did not grow after the delivery. After delivery, the PMC of one of these four patients remained stable, and another showed a decrease in PMC size. To date, six more PMC patients underwent surgery after delivery for reasons other than disease progression due to pregnancy and delivery: two opted out of active surveillance, two were identified with a nodal metastasis during active surveillance after delivery, one had Graves' disease, and one showed enlargement of nodules of the contralateral lobe.

CONCLUSIONS

Pregnancy and delivery was associated with an increase in size of PMCs in only 8% of the 51 pregnancies/delivery cases. None of the patients developed nodal metastasis during pregnancy. Thus, a possible future pregnancy does not prevent such patients from undergoing active surveillance, although watchful observation during pregnancy is recommended.

Innervation of the cricothyroid muscle by extralaryngeal branches of the recurrent laryngeal nerve

Objectives/Hypothesis

A major concern in thyroid surgery is possible changes in the patient's voice due to dysfunction of the laryngeal muscles. The classical understanding of the anatomy is that the cricothyroid muscle (CTM) is innervated solely by the external branch of the superior laryngeal nerve (EBSLN), and the endolaryngeal muscles are covered only by the recurrent laryngeal nerve (RLN). Meticulous anatomical studies found communication between these nerves. Recent neurophysiological studies revealed cross‐innervations among these nerve–muscle sets. Here, we report innervation of the CTM by extralaryngeal branches of the RLN.

Study Design

Clinical observation during thyroid surgery at a hospital center for thyroid diseases.

Methods

During thyroid cancer surgeries, we encountered four adult Japanese patients who had an extralaryngeal branch of the RLN, the electrical stimulation of which showed contraction of the CTM. The EBSLN and RLN were electrically stimulated. Responses were evaluated by visual observation of contraction of the CTM and palpable laryngeal twitch of the endolaryngeal muscles. Electromyographic studies were also performed in two patients.

Results

Five of the seven RLNs examined showed contraction of the CTM on stimulation. Four of these five RLNs had an extralaryngeal branch that showed contraction of the CTM on stimulation. Stimulation of the RLN proximal to the branch yielded contraction of the CTM and laryngeal twitch, whereas stimulation of the RLN distal to the branch yielded only laryngeal twitch.

Conclusions

Extralaryngeal branches of the RLN innervated the CTM in four patients. This phenomenon might influence voice changes following thyroid surgery.

Level of Evidence

4. Laryngoscope, 126:1157–1162, 2016

Impact of positional changes in neural monitoring endotracheal tube on amplitude and latency of electromyographic response in monitored thyroid surgery: Results from the Porcine Experiment

BACKGROUND

The purpose of this study was to evaluate electromyography (EMG) amplitude and latency changes during tube dislocation in monitored thyroid surgery, which may be observed without recurrent laryngeal nerve injury.

METHODS

Duroc-Landrace piglets were intubated with the TriVantage EMG tube. We measured EMG changes during both upward and downward tube dislocation (10-20 mm) and rotation (45-90°) with continuous neuromonitoring.

RESULTS

The EMG amplitude varied significantly with induced endotracheal tube rotation and depth changes. However, the EMG latency was relatively unaffected by such tube dislocation, just a transient artifactual latency change was observed in the situation of extreme amplitude variation.

CONCLUSION

Amplitude changes without latency changes may be due to changes in tube position alone during surgery, but could still reflect a neurophysiologic event; amplitude changes during neuropraxic injury merit additional investigation. Thus, the combined event (concordant amplitude decrease and latency increase) serves as an appropriate adverse EMG event correlating with impending neural injury. © 2015 Wiley Periodicals, Inc. Head Neck 38: E1004-E1008, 2016.

Innervation of the cricothyroid muscle by the recurrent laryngeal nerve

Background

The recurrent laryngeal nerve (RLN) and the external branch of the superior laryngeal nerve (SLN) are generally thought to innervate the endolaryngeal muscles and the cricothyroid muscle (CTM), respectively. Meticulous anatomic studies found communication between these nerves (ie, the human communicating nerve). In this study, we report the innervation of the CTM by the RLN.

Methods

We performed electromyographic studies of 50 patients during thyroidectomy (20 total and 30 hemithyroidectomies). During surgery, the external branch of the SLN, RLN, and vagus nerve were stimulated. Responses were evaluated by visual observation of the CTM and by electromyographies through needle electrodes inserted into the CTM.

Results

Seventy CTMs were evaluated. The RLN stimulation yielded both visible contractions and clear electromyographic responses (>300 µV) in 27 (39%), either response in 24 (34%), and neither response in 19 (27%) of the CTMs. The vagus stimulation gave similar results.

Conclusion

The RLN innervated the CTM at least in 39% cases. © 2015 The Authors. Head & Neck Published by Wiley Periodicals, Inc. Head Neck38: E441–E445, 2016