Thyroid Ultrasound Findings in Children from Three Japanese Prefectures: Aomori, Yamanashi and Nagasaki

Abstract

Due to the likelihood of physical and mental health impacts following the unprecedented accident at the Fukushima Dai-ichi Nuclear Power Plant, the Fukushima prefectural government decided to conduct the Fukushima Health Management Survey to assist in the long-term health management of residents. This included thyroid ultrasound examination for all children in Fukushima. For appropriate evaluation of ultrasound screening of the thyroid, it is important to understand its reference data of thyroid findings in children in general. In order to analyze the frequencies of specific thyroid findings, we conducted ultrasound screening of the thyroid by the same procedures as used in Fukushima in 4,365 children, aged 3 to 18 years, from three Japanese prefectures. Overall, thyroid cysts were identified in 56.88% and thyroid nodules in 1.65% of the participants. Thyroid cysts and nodules with a maximum diameter of more than 5 mm were identified in 4.58% and 1.01%, respectively, and age-adjusted prevalences were 3.82% and 0.99%, respectively. Although the prevalence of cysts and nodules varied among the examination areas, no significant differences were observed among the three examination areas in the prevalence of cysts and nodules with a maximum diameter of more than 5 mm. Also, the prevalence of thyroid cysts and nodules, especially those with a maximum diameter of more than 5 mm, significantly increased with age, and showed a female predominance. We also identified ectopic thymus (1.95%), diffuse goiter (1.40%), ultimobranchial body (0.73%), lymph node swelling (0.21%) and thyroid agenesis (0.05%). This is the first ultrasound description of the age-adjusted prevalence of thyroid cysts and nodules, or of the prevalence of abnormalities other than cysts and nodules, such as ectopic thymus, in relation to age, in the general Japanese child population. We contend that this can provide relevant information for the Fukushima Health Management Survey and future population studies.

Changes in pediatric thyroid sonograms in or nearby the Kanto region before and after the accident at the Fukushima Daiichi nuclear power plant

“…Factors possibly involved in the differences in the incidence rates among different reports include regional differences in the age distribution or iodine intake, family history, differences in the ultrasonographic devices used, differences in the examiners, etc., although no definitive reason has been identified yet. An intrathyroidal ectopic thymus was detected in 9 individuals (4.2%), and its incidence rate decreased with age, similar to the tendency reported by Hayashida N et al [18]. Regarding the development of the thymus, it is known that the epithelium of the third pharyngeal pouch grows to close the inner medulla, then the bilateral primordia of the thymus fuse with each other on the median plane, forming the thymus.…”

“…Concerning comparison of the results in this study with the data reported from other districts, the survey of Fukushima Prefecture inhabitants conducted by the Fukushima Prefectural Government revealed cysts in 102594 individuals (45.5%) among the 225537 individuals surveyed, the cysts measuring ≤ 5 mm in diameter in 102583 of the 102594 individuals (99.99% cases) (data as of August 23, 2013 published on the prefecture's homepage) [10]. According to the report by Hayashida N et al, who published combined data from 3 districts (Hirosaki City Aomori Prefecture, Kofu City Yamanashi Prefecture and Nagasaki City Nagasaki Prefecture), cysts were detected in 2483 (56.9%) of 4365 individuals, the cysts measuring ≤ 5 mm in diameter in 2283 of the individuals (91.9%) [18]. In all of these surveys, the incidence rate of cysts was high and cysts ≤ 5 mm in diameter accounted for the overwhelming majority of the cases, similar to the tendency observed at our facility.…”

“…According to the Fukushima Prefecture Government's report, nodules were detected in 2710 (1.2%) of 225537 individuals, including nodules > 5 mm in diameter in 1541 individuals (56.9%) [10]. According to the report of Hayashida N et al, nodules were detected in 72 (1.65%) of 4365 individuals, including nodules > 5 mm in diameter in 44 individuals (61.1%) [18]. In the international literature, Avulas et al performed thyroid ultrasonography on 287 individuals (mean age 8.1) visiting their facility in Toronto (Canada) with chief complaints not related to the thyroid, and reported that cysts (< 4 mm in diameter) were detected…”

The role of the ultrasound scanning in the diagnostics of the thyroid gland of children and adolescents

“…Naukowcy z Japonii ocenili również w badaniu ultrasonograficznym tarczycę w 3 regionach swojego kraju wśród 4365 dzieci w wieku 3-18 lat, stwierdzając w 72 (1,65%) przypadkach guzki tarczycy, 61 (1,4%) wole, a u dwojga dzieci agenezję tarczycy (0,04%) [28].…”

Comments to part of the American thyroid association guidelines for the management of thyroid nodules in children

“…В отноше-нии распространенности узлов у детей по данным ультразвукового исследования (УЗИ) и по данным DOI: 10.14341/ket2015440 50 © "Клиническая и экспериментальная тиреоидология", 2015 ауто псии приводятся цифры от 1-5% у детей до 13% у подростков [13,14], причем в первом проспективном исследовании [13] речь идет в основном о частоте РЩЖ и возможном влиянии на его развитие Чернобыльской катастрофы, а вторая работа датирует-ся 1965 г. и даже реферата мне найти не удалось. Вместе с тем дается ссылка на крупное эпидемиологическое исследование, проведенное в Японии [15], в котором на ультразвуковом аппарате экспертного класса было обследовано 4365 детей в возрасте от 3 до 18 лет и вы-явлено 56,88% кистозных образований в ЩЖ, из них только 4,58% диаметром >5 мм, а также 1,65% солид-ных узлов, из них диаметром >5 мм -1,01%. Кроме того, авторами отмечается очень высокая частота экто-пии тимуса (в среднем среди всех возрастных групп -1,95%) с пиком на возраст от 3 до 9 лет -4,6%!…”