谷 好子¹, 丸田 淳子², 衞藤 美佐子¹, 野口 仁志³, 檜垣 直幸³, 西嶋 由衣³, 内野 眞也⁴, 横山 繁生², 村上 司³

Yoshiko TANI¹, Junko MARUTA², Misako ETO¹, Hitoshi NOGUCHI³, Naoyuki HIGAKI³, Yui NISHIJIMA³, Shinya UCHINO⁴, Shigeo YOKOYAMA², Tsukasa MURAKAMI³

¹野口病院研究検査科, ²野口病院病理診断科, ³野口病院内科, ⁴野口病院外科

¹Department of Laboratory, Noguchi Thyroid Clinic and Hospital Foundation, ²Department of Diagnostic Pathology and Cytology, Noguchi Thyroid Clinic and Hospital Foundation, ³Department of Endocrinology, Noguchi Thyroid Clinic and Hospital Foundation, ⁴Department of Surgery, Noguchi Thyroid Clinic and Hospital Foundation

キーワード : thyroid nodule, ultrasonography, histology, substances causing fine strong echoes

目的：良性および悪性甲状腺結節における微細高エコーの出現頻度とその原因物質，超音波所見から原因物質の推定が可能かを明らかにする．対象と方法：甲状腺結節性病変144例（乳頭癌56例，濾胞癌4例，濾胞腺腫57例，腺腫様甲状腺腫27例）の超音波所見と組織所見を比較検討した．結果：微細高エコーは乳頭癌の69.6％に認められ，他の組織型と比べ有意に高頻度であったが，濾胞腺腫の21.1％，腺腫様甲状腺腫の25.9％にも観察された．組織学的に，微細高エコーがみられた58例全例に砂粒体，線維組織内小石灰化，シュウ酸カルシウム結晶，コレステリン結晶，砂粒体様物質のいずれかが観察され，微細高エコーのない86例中76例にはこれらの微細構造物は認められなかった．考察：微細高エコーと組織学的な微細構造物の有無は93.1％の症例で一致しており，超音波画像の微細高エコーは5種類の微細構造物を反映していると考えられた．超音波画像のみで原因物質の推定は困難であったが，無エコー結節内でコメットサインを伴い緩やかに移動するものはコレステリン結晶，動きのないものはシュウ酸カルシウム結晶の可能性が高かった．結論：甲状腺良性結節の22.6％に微細高エコーを認め，原因物質は，砂粒体以外の4種の微細構造物であった．超音波像で微細高エコーの原因物質を鑑別することは困難であったが，付随所見を考慮することで，一部の原因物質の推定は可能であった．

Purpose: The aim of this study was to investigate the incidence of fine strong echoes in benign and malignant thyroid nodules and their causative substances, as well as whether it was possible to ultrasonographically distinguish them. Subjects and Methods: A total of 144 resected nodules were used, including 56 cases of papillary carcinoma (PC), four cases of follicular carcinoma (FC), 57 cases of follicular adenoma (FA), and 27 cases of adenomatous goiter (AG). We compared and examined ultrasonographic and histologic findings for each histological type, with a particular focus on the features of fine strong echoes, their causative substances, and the correlation between them. Results: Fine strong echoes were observed in PCs with a significantly high incidence of 69.6% (39 cases, p＜0.0001), but also in 21.1% of FA (12 cases) and 25.9% of AG (7 cases). In the 58 positive cases, one or two of five microstructures (psammoma bodies, irregular-shaped microcalcifications in fibrous stroma, calcium oxalate crystal, cholesterol crystals, and psammoma body-like structures) were histologically observed, while they were absent in 76 of the 86 negative cases. Discussion: The presence or absence of fine strong echoes was coincident with the presence or absence of the five microstructures in 93.1% of cases. Fine strong echoes on ultrasound images were considered to reflect these microstructures. Fine strong echoes due to the microstructures looked like each other, but taking incidental findings into account, ultrasonographic estimation of the microstructures may be possible. In anechoic nodules, slow-moving fine strong echoes with comet signs and fixed ones are likely to be cholesterol crystals and calcium oxalate crystals, respectively. Conclusion: Fine strong echoes were observed in 22.6% of benign thyroid nodules. Their causative substances were four types of microstructures other than psammoma bodies. Calcium oxalate crystals and cholesterol crystals in the anechoic nodules may be estimated based on ultrasound images, although it seems difficult to distinguish them in most cases.