随着新的甲状腺交界性病变和良恶性“灰色地带”的不断发现，加之传统免疫指标的局限性，甲状腺乳头状癌（PTC）的鉴别诊断变得更加困难。 Cyclin D1和P21是细胞周期调节因子，参与包括PTC在内的多种肿瘤的发生和转移，但其具体功能尚不清楚。本研究采用免疫组化染色方法探讨Cyclin D1和P21在PTC、癌旁组织中的表达情况、滤泡性腺瘤（FA）和甲状腺乳头状增生。此外，还研究了它们与PTC临床病理特征的关系以及区分淋巴结内PTC转移灶和淋巴结内异位甲状腺组织的鉴别诊断价值。在200个原发性PTC病灶中，发现Cyclin D1和P21在186个（分别为 93.00%）和 177 个（88.50%），其在 PTC 组织中的表达量显着高于癌旁组织、FA 组织和甲状腺乳头状增生组织（P < 0.05）。 Cyclin D1、P21的表达水平与肿瘤大小、淋巴结转移呈正相关（P<0.05），但与性别、年龄、病灶数量、组织学亚型、慢性淋巴细胞性甲状腺炎及TNM分期无关（P<0.05）。 Cyclin D1和P21的表达水平具有显着相关性(P<0.05)。淋巴结内PTC转移灶中Cyclin D1和P21的阳性率分别为97.96%（48/49）和89.80%（44/49），显着高于淋巴结内异位甲状腺组织（P < 0.05）。 Cyclin D1和P21单独或联合检测的灵敏度（Se）和阴性预测值（NPV）均高于经典抗体标志物CK19、HBME-1和Galectin-3联合检测的灵敏度（Se）和阴性预测值（NPV）。此外，Cyclin D1和P21在鉴别淋巴结内PTC转移瘤和淋巴结内异位甲状腺组织中的Se、Sp、PPV和NPV较高。我们的研究结果表明，Cyclin D1和P21是诊断的高度敏感和特异的标志物。 PTC 优于传统经典抗体。而且，这两个标志物对于淋巴结内 PTC 转移瘤和淋巴结内异位甲状腺组织的鉴别诊断具有重要价值。© 2023。作者。

With the continuous discovery of new borderline thyroid lesions and benign and malignant "gray areas", coupled with the limitations of traditional immune indicators, the differential diagnosis of papillary thyroid carcinoma (PTC) has become more difficult. Cyclin D1 and P21 are cell cycle regulators involved in the occurrence and metastasis of multiple tumors, including PTC, but their specific functions are unclear.In our study, immunohistochemical staining was used to explore the expression of Cyclin D1 and P21 in PTC, paracancerous tissue, follicular adenoma (FA) and papillary thyroid hyperplasia. In addition, their relationship with the clinicopathological features of PTC and their differential diagnostic value in distinguishing between intralymph node PTC metastases and intralymph node ectopic thyroid tissue were studied.Among 200 primary PTC lesions, Cyclin D1 and P21 were found to be expressed in 186 (93.00%) and 177 (88.50%), respectively, and their expression levels were significantly higher in PTC tissue than in adjacent tissue, FA tissue and papillary thyroid hyperplasia tissue (P < 0.05). The expression levels of Cyclin D1 and P21 were positively correlated with tumor size and lymph node metastasis (P < 0.05) but not with sex, age, number of tumor lesions, histological subtype, chronic lymphocytic thyroiditis or TNM stage (P < 0.05). The expression levels of Cyclin D1 and P21 were significantly correlated (P < 0.05). The positivity rates of Cyclin D1 and P21 in intralymph node PTC metastases were 97.96% (48/49) and 89.80% (44/49), respectively, which were significantly higher than those in intralymph node ectopic thyroid tissue (P < 0.05). The sensitivity (Se) and negative predictive value (NPV) of Cyclin D1 and P21 detection alone or in combination were higher than those of the combined detection of the classical antibody markers CK19, HBME-1 and Galectin-3. Besides, the Se, Sp, PPV and NPV of Cyclin D1 and P21 in differentiating intralymph node PTC metastases and intralymph node ectopic thyroid tissue were higher.The results of our study show that Cyclin D1 and P21 are highly sensitive and specific markers for the diagnosis of PTC that are superior to traditional classical antibodies. And, these two markers are of great value in the differential diagnosis of intralymph node PTC metastases and intralymph node ectopic thyroid tissue.© 2023. The Author(s).