Case presentation and overview

The patient is a 19-year-old female who had an incidental thyroid nodule discovered on magnetic resonance imaging (MRI) in July 2020 during the work-up of a superficial, midline neck cellulitis. She reported having noticed a bulge in her neck a few years prior but had never been concerned about it. She began seeing an endocrinologist and underwent a thyroid ultrasound in July 2020, which revealed a solid, hypoechoic nodule in the left upper thyroid lobe measuring 2.2 cm in greatest dimension, classified as American College of Radiology Thyroid Imaging Reporting and Data System (ACR TI-RADS) 4 (Figure 1). Multiple, enlarged, abnormal-appearing lymph nodes were also noted in the left cervical lymph node chain in level IV (Figure 2). The lower pole of the left thyroid lobe was heterogeneous, with scattered calcifications and subcentimeter cystic areas, and no abnormal findings were noted in the isthmus or right lobe of the thyroid gland. Her thyroid function tests were normal, with a thyroid-stimulating hormone (TSH) level of 2.34 mU/L (reference range, 0.45–5.33 mU/L) and a T4 (thyroxine) level of 0.88 ng/dL (reference range, 0.58–1.64 μg/dL), with negative thyroid peroxidase antibodies and normal blood cell counts.

A fine-needle aspiration (FNA) of the left thyroid nodule was performed in September 2020 and revealed papillary thyroid cancer (PTC). The patient was then referred to the endocrine surgery clinic for evaluation and further management. An FNA biopsy of the concerning left lateral cervical lymph nodes (Figure 2) was conducted in the endocrine surgery clinic because it had not previously been performed. Given the concerning appearance of the lymph nodes on ultrasound, a total thyroidectomy with possible left central and lateral neck dissections was discussed as the likely operation pending pathology results from the lymph node biopsy. The patient agreed with the treatment plan, and FNA results from the lymph nodes returned as metastatic PTC.

Given the evidence of metastatic lymph node disease, the patient underwent a total thyroidectomy along with left central and lateral neck dissections in October 2020. Intraoperatively, a very firm nodule in the left lobe of the thyroid gland was encountered that was unable to be cleanly separated from the overlying sternothyroid muscle. Given concern for extrathyroidal extension, the muscle was resected en bloc with the thyroid specimen. During the dissection, there was concern for devascularization of the left superior parathyroid gland, so it was excised and re-implanted. However, there was significant lymphadenopathy low in cervical level VI surrounding the left inferior parathyroid gland, making clear identification of the inferior gland difficult. A frozen section was obtained that confirmed the identification of the left inferior parathyroid gland, so it was also re-implanted into the left sternocleidomastoid muscle. Bulky lymphadenopathy was found throughout the left central and lateral neck (levels II–VI) during the neck dissection.

Surgical pathology revealed a greatest tumor dimension of 4.5 cm with lymphovascular invasion but no extrathyroidal extension and clear resection margins. Five of the seven resected lymph nodes from the central neck and nine of the 19 nodes in the lateral neck showed PTC without extranodal extension. The overall pathologic stage was pT3aN1b.

Postoperatively, the patient experienced transient hypocalcemia, which required 8 weeks of calcium supplementation. Her 6-week postoperative thyroglobulin (Tg) level was 0.6 ng/mL in December 2020. A diagnostic whole-body scan in January 2021 revealed physiologic uptake in the thyroidectomy bed with no evidence of metastatic disease. She subsequently underwent radioactive iodine (RAI) therapy with 157.7 millicuries (mCi) of iodine-131 (¹³¹I), and her postablation scan similarly showed physiologic uptake in the thyroidectomy bed with no evidence of metastatic disease (Figures 3 and 4). Subsequent thyroid ultrasound studies in April and September of 2021 also showed no evidence of recurrent disease or suspicious findings throughout the thyroid bed or bilateral cervical chains I–VI. Her Tg level was undetectable (<0.1 ng/mL) in October 2021 after her RAI therapy.

中文翻译：

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虚拟肿瘤委员会：甲状腺乳头状癌伴淋巴结病

案例介绍和概述

该患者是一名 19 岁女性，2020 年 7 月在检查浅表中线颈部蜂窝织炎期间，通过磁共振成像 (MRI) 偶然发现了甲状腺结节。她报告说几年前就注意到自己脖子上有一个凸起，但从未担心过。她开始去看内分泌科医生，并于 2020 年 7 月接受了甲状腺超声检查，结果显示左甲状腺上叶有一个实性低回声结节，最大尺寸为 2.2 厘米，被归类为美国放射学会甲状腺成像报告和数据系统 (ACR TI- RADS）4（图1）。IV 级左颈淋巴结链中还发现多个、肿大、外观异常的淋巴结（图 2）。甲状腺左叶下极不均匀，有散在钙化和亚厘米囊性区，峡部或甲状腺右叶未见异常。她的甲状腺功能测试正常，促甲状腺激素 (TSH) 水平为 2.34 mU/L（参考范围，0.45–5.33 mU/L），T4（甲状腺素）水平为 0.88 ng/dL（参考范围，0.58） –1.64 μg/dL），甲状腺过氧化物酶抗体呈阴性且血细胞计数正常。

2020 年 9 月对左侧甲状腺结节进行细针抽吸 (FNA)，结果显示甲状腺乳头状癌 (PTC)。随后，患者被转诊至内分泌外科诊所进行评估和进一步治疗。由于以前从未进行过相关左侧颈淋巴结的 FNA 活检（图 2），因此在内分泌外科诊所进行。鉴于超声检查中淋巴结的外观令人担忧，因此讨论了甲状腺全切除术以及可能的左中央和侧颈清扫术，作为可能的手术，等待淋巴结活检的病理结果。患者同意治疗计划，淋巴结 FNA 结果显示为转移性 PTC。

鉴于转移性淋巴结疾病的证据，患者于2020年10月接受了甲状腺全切除术以及左中央和侧颈清扫术。术中发现甲状腺左叶有一个非常坚硬的结节，无法干净地分离来自上面的胸骨甲状肌。考虑到甲状腺外延伸，肌肉与甲状腺标本一起被切除。在解剖过程中，担心左上甲状旁腺断流，因此将其切除并重新植入。然而，左下甲状旁腺周围的颈部VI低位有明显的淋巴结肿大，使得清楚识别下腺体变得困难。获得的冰冻切片证实了左下甲状旁腺的识别，因此它也被重新植入到左胸锁乳突肌中。在颈部清扫过程中，在整个左颈中央和侧颈（II-VI 级）发现大量淋巴结肿大。

手术病理显示肿瘤最大尺寸为 4.5 厘米，有淋巴管侵犯，但无甲状腺外扩展，切除边缘清晰。中央颈切除的 7 个淋巴结中的 5 个和侧颈 19 个淋巴结中的 9 个显示 PTC，无结外扩散。总体病理分期为pT3aN1b。

术后患者出现短暂性低钙血症，需要补钙8周。2020 年 12 月，她术后 6 周的甲状腺球蛋白 (Tg) 水平为 0.6 ng/mL。2021 年 1 月的诊断性全身扫描显示甲状腺切除床上的生理摄取，没有转移性疾病的证据。随后，她接受了 157.7 毫居里 (mCi) 碘 131 ( ¹³¹ I) 放射性碘 (RAI) 治疗，她的消融后扫描同样显示甲状腺切除床上的生理摄取，没有转移性疾病的证据（图 3 和 4）。随后于 2021 年 4 月和 9 月进行的甲状腺超声研究也显示，整个甲状腺床或双侧颈链 I-VI 中没有疾病复发或可疑发现的证据。2021 年 10 月，RAI 治疗后，她的 Tg 水平检测不到（<0.1 ng/mL）。