1 Department of Medicine, Kuma Hospital , Kobe, Japan .
2 Department of Pathology, Kuma Hospital , Kobe, Japan .
Thyroid. 2015 Jul;25(7):804-11. doi: 10.1089/thy.2014.0567. Epub 2015 May 18.
Most benign thyroid nodules found on fine-needle aspiration cytology (FNAC) can be followed with periodic ultrasonography. During follow-up, when nodules grow, re-aspiration or surgical resection for a histologic diagnosis is recommended. However, there is little evidence regarding the malignancy risk associated with nodule growth.
We retrospectively reviewed the records of 542 patients with FNAC-diagnosed adenomatous nodules (ANs) who underwent surgery in 2011-2012 at Kuma Hospital. Among them, 196 patients had surgical resection because of nodule volume growth (median, 1.94 times; range, 1.21-27.60) during the observation period (mean, 45.9 months). Excluding nodule growth, the remaining 346 patients underwent surgery for various reasons including the large size of nodules or the appearance of undefined ultrasound features suspicious for malignancy during follow-up. For comparison, we reviewed 409 patients with FNAC-diagnosed follicular neoplasms (FNs) operated on in 2011-2013. Most (n=327) underwent surgery shortly after the FNAC diagnosis, while 82 patients were observed for a period of time and had a late operation due to nodule volume growth (median, 2.70 times; range, 1.27-15.82).
The histologic diagnoses of the 196 growing FNAC-diagnosed ANs were 158 ANs, 32 follicular adenomas (FAs), 4 follicular tumors of uncertain malignant potential (FT-UMP; 2%), and 2 malignancies (1%). The 346 patients who underwent surgery for reasons other than nodular growth had 16 FT-UMP (4.6%) and 16 malignancies (4.6%). This suggests that nodule growth itself is not a risk factor for malignancy. On the other hand, there were 23 FT-UMP (28%) and 15 malignancies (18.3%) in the 82 growing FNAC-diagnosed FNs, while 44 FT-UMP (13.5%) and 54 malignancies (16.5%) in the 327 FNAC-diagnosed FN patients who underwent immediate surgery. The malignant potential was significantly higher in the growing-FN group than the immediate-surgery FN group (p<0.05). No significant difference was found in the volume change between the benign and the FT-UMP plus malignant group in the growing FNs, suggesting that a growth rate does not correlate with malignant potential.
This is the first demonstration that the malignancy risk is low in FNAC-diagnosed ANs, even if the nodules grow significantly, whereas FNs have a higher risk when they grow.
大多数在细针穿刺细胞学（FNAC）检查中发现的良性甲状腺结节可以通过定期超声检查进行随访。在随访过程中，当结节生长时，建议重新进行抽吸或手术切除以进行组织学诊断。然而，关于结节生长与恶性风险之间的关联，证据有限。
我们回顾性分析了 2011 年至 2012 年在久留米医院接受手术的 542 例 FNAC 诊断为腺瘤性结节（ANs）患者的病历。其中，196 例因结节体积在观察期间（平均 45.9 个月）增长（中位数 1.94 倍；范围 1.21-27.60）而进行了手术切除。排除结节生长的情况，其余 346 例因结节体积较大或在随访期间出现超声特征不明确的恶性肿瘤等原因进行了手术。为了进行比较，我们回顾了 2011 年至 2013 年接受 FNAC 诊断为滤泡性肿瘤（FNs）并接受手术的 409 例患者的病历。大多数（n=327）在 FNAC 诊断后不久即进行了手术，而 82 例患者进行了一段时间的观察，由于结节体积增长（中位数 2.70 倍；范围 1.27-15.82）而进行了晚期手术。
196 例 FNAC 诊断为生长性 ANs 的组织学诊断为 158 例 ANs、32 例滤泡性腺瘤（FA）、4 例滤泡性肿瘤不确定恶性潜能（FT-UMP；2%）和 2 例恶性肿瘤（1%）。346 例因结节生长以外的其他原因进行手术的患者中有 16 例 FT-UMP（4.6%）和 16 例恶性肿瘤（4.6%）。这表明结节生长本身并不是恶性肿瘤的危险因素。另一方面，在 82 例生长性 FNAC 诊断为 FNs 中有 23 例 FT-UMP（28%）和 15 例恶性肿瘤（18.3%），而在 327 例立即接受手术的 FNAC 诊断为 FN 患者中有 44 例 FT-UMP（13.5%）和 54 例恶性肿瘤（16.5%）。生长性 FN 组的恶性潜能明显高于立即手术的 FN 组（p<0.05）。在生长性 FNs 中，良性和 FT-UMP 加恶性组之间的体积变化没有显著差异，这表明生长速度与恶性潜能无关。
这是首次表明 FNAC 诊断为 ANs 的结节即使显著生长，恶性风险也较低，而 FNs 生长时风险较高。
