Sonographic Features of Multifocal Papillary Thyroid Carcinomas

Dong Wook Kim, MD; Gi Won Shin, MD; Yoo Jin Lee, MD; Soo Jin Jung, MD; Hye Jin Baek, MD; Taewoo Kang, MD

Disclosures

Endocr Pract. 2018;24(4):351-360. 

In This Article

Abstract and Introduction

Abstract

Objective: It is uncertain whether papillary thyroid carcinomas (PTCs) of the same subtype display similar sonographic features. This retrospective analysis of pre-operative sonographic and pathologic findings aimed to assess whether PTCs of the same subtype share sonographic features.

Methods: Before undergoing thyroid surgery, 137 patients underwent ultrasound (US) examination. A single radiologist used a picture archiving and communication system and pathologic reports to investigate all sonographic features of the largest and second largest PTCs. Additionally, the radiologist evaluated the similarity of sonographic features between primary (largest), secondary (second largest), and daughter (secondary with same subtype as the primary) PTCs.

Results: Of the 137 PTC patients, 48 (35.0%) had multiple PTCs; however, 5 had no US images of the secondary PTC. Of the 43 secondary PTCs with US images, 9 (20.9%) secondary PTCs were of a different subtype than the primary PTC and revealed sonographic features that differed from those of the primary PTC. Of the 48 patients with multiple PTCs, the subtype was the same in the primary and secondary PTCs in 34 (70.8%) patients. Of the 34 daughter PTCs, 32 (94.1%) had sonographic features similar to those of the primary PTC, whereas 2 (5.9%) showed different sonographic features than the primary PTC. There was no significant difference between primary and daughter PTCs in the size, location, sonographic features, or Korean Thyroid Imaging Reporting and Data System category (P>.05).

Conclusion: Daughter PTCs show similar sonographic features as the primary PTC.

Introduction

Papillary thyroid carcinoma (PTC) is the most common type of thyroid malignancy.[1] In patients with thyroid nodules that are suspicious for PTC on cytology, ultrasound (US) is the most popular preoperative diagnostic tool for the evaluation of tumor stage, nodal stage, multifocality, and bilaterality.[1] PTC frequently presents with multifocal or bilateral tumors.[2–4] Although still controversial, the multifocality and bilaterality of PTC may be associated with an increased risk of disease recurrence and/or persistence.[2] Before thyroid surgery, US evaluation for the bilaterality of PTC helps surgeons choose between hemithyroidectomy or total thyroidectomy in patients considered to be at low risk.[1]

To date, the reported malignant sonographic features of thyroid nodules include hypo-echogenicity, microcalcifications, a spiculated/microlobulated margin, and a taller-than-wide shape.[5–8] In comparison with other thyroid malignancies, PTC tends to demonstrate malignant sonographic features.[5–7] However, the pathologic subtypes of PTC vary. In the literature, the follicular variant of PTC tends to have no malignant sonographic features, and it commonly shows sonographic features similar to those of follicular thyroid carcinoma.[9] In practice, surgeons may select an inappropriate type of surgery for PTC patients due to a misdiagnosis of bilaterality during the preoperative US examination. In a patient with a thyroid nodule that is suspicious for PTC on cytology, the presence of a smaller thyroid nodule showing similar sonographic features in the contralateral lobe would indicate that a total thyroidectomy is needed.[10] However, it is uncertain whether PTCs of the same subtype show the same sonographic features. Thus, using a retrospective analysis of preoperative sonographic and pathologic findings, this study aimed to evaluate sonographic features of multifocal PTCs and to assess whether PTCs of the same subtype share sonographic features.

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