Brutsaert Erika F, Gersten Adam J, Tassler Andrew B, Surks Martin I
Department of Medicine, Division of Endocrinology (E.F.B., M.I.S.), Department of Pathology (A.J.G.), and Department of Otorhinolaryngology (A.B.T.), Montefiore Medical Center, Bronx, New York 10467.
J Clin Endocrinol Metab. 2015 Feb;100(2):337-41. doi: 10.1210/jc.2014-3095. Epub 2014 Dec 9.
Calcitonin is a sensitive biomarker that is used for diagnosis and follow-up in medullary thyroid cancer (MTC). In patients with tumors > 1 cm, it is uncommon for preoperative serum calcitonin to be in the normal laboratory reference range in patients with MTC, and even more unusual for serum calcitonin to be undetectable.
A 39-year-old woman was found to have a left thyroid nodule on magnetic resonance imaging done for neck pain. Ultrasound and fine-needle aspiration biopsy were performed, and cytopathology was positive for malignant cells. The cells also had features suggestive of a neuroendocrine tumor, and the specimen was immune-stained with calcitonin. There was positive immunoreactivity for calcitonin in isolated cells of the cytospin, highly favoring a diagnosis of MTC. Serum calcitonin was < 2 pg/mL (<6 pg/mL), and serum carcinoembryonic antigen was 3.1 ng/mL (<5.2 ng/mL). Given the low calcitonin levels, procalcitonin was also tested and was elevated at 0.21 ng/mL (< 0.1 ng/mL). The patient subsequently underwent a total thyroidectomy and central and ipsilateral lateral lymph node dissection. Histopathology confirmed a 2.6 × 2.0 × 1.2-cm MTC, with strong, diffuse immunostaining for calcitonin. Postoperatively, serum calcitonin has remained undetectable, carcinoembryonic antigen has remained within the reference range, and procalcitonin has become undetectable.
We present a rare case of a patient with MTC with undetectable preoperative serum calcitonin, whose tumor demonstrated strong, diffuse immunohistochemical staining for calcitonin. We discuss the possible pathogenesis of calcitonin-negative MTC and the challenges in following patients with this condition.
降钙素是一种敏感的生物标志物，用于甲状腺髓样癌（MTC）的诊断和随访。对于肿瘤直径>1 cm的患者，MTC患者术前血清降钙素处于正常实验室参考范围内的情况并不常见，血清降钙素无法检测到的情况则更为罕见。
一名39岁女性因颈部疼痛进行磁共振成像检查时发现左侧甲状腺结节。进行了超声和细针穿刺活检，细胞病理学检查显示恶性细胞阳性。细胞还具有神经内分泌肿瘤的特征，标本用降钙素进行免疫染色。细胞涂片的单个细胞中降钙素免疫反应呈阳性，高度支持MTC的诊断。血清降钙素<2 pg/mL（<6 pg/mL），血清癌胚抗原为3.1 ng/mL（<5.2 ng/mL）。鉴于降钙素水平较低，也检测了降钙素原，其升高至0.21 ng/mL（<0.1 ng/mL）。该患者随后接受了全甲状腺切除术及中央和同侧侧方淋巴结清扫术。组织病理学证实为2.6×2.0×1.2 cm的MTC，降钙素免疫染色强且弥漫。术后，血清降钙素一直无法检测到，癌胚抗原一直处于参考范围内，降钙素原也变得无法检测到。
我们报告了一例罕见的MTC患者，其术前血清降钙素无法检测到，但其肿瘤降钙素免疫组化染色强且弥漫。我们讨论了降钙素阴性MTC的可能发病机制以及对此类患者进行随访的挑战。
