Kim Wook Youn, Oh Seo Young, Kim Hyunkyung, Hwang Tae Sook
Department of Pathology, the Research Institute of Medical Science, Konkuk University School of Medicine, Seoul, Korea.
Department of Pathology, Konkuk University Medical Center, Seoul, Korea.
Diagn Cytopathol. 2016 May;44(5):450-8. doi: 10.1002/dc.23441. Epub 2016 Jan 23.
In fine needle aspiration biopsy (FNAB) of thyroid nodules, LBC is adopted in most of the hospitals and clinics in Korea for its convenience. BRAF mutation test has been introduced as an important ancillary test, but its applicability has not been completely proven with LBC samples.
Five aspirates from thyroidectomy specimens were simultaneously processed into LBC and CS slides, in which BRAF mutation tests were performed using three primer sets with PCR products of 72, 164, and 226 base pairs (bp) at 6, 9, and 12 months after processing. In addition, BRAF mutation tests were performed in nine clinical samples that had been prepared by LBC or CS and stored for 3-5 years after processing.
At 9 months after processing, LBC failed to provide DNA of sufficient quality for PCR, whereas CS succeeded with primers for amplifying a 226 bp fragment. Furthermore, CS had successful amplification of DNA despite a delay of more than 1 year. The failure of DNA amplification in LBC was overcome by using primers to amplify shorter PCR products, suggesting that DNA degradation occurred in LBC. However, false positive or negative results were observed in primers for amplifying shorter size. The kind of preservative solutions used in LBC did not affect test results.
LBC may have disadvantages in long-term DNA preservation because of its accelerated DNA degradation compared with alcohol-fixed CS. Using primers to amplify shorter size fragments might be helpful in mitigating loss of signal due to DNA degradation in LBC.
在甲状腺结节细针穿刺活检（FNAB）中，韩国大多数医院和诊所采用液基薄层制片（LBC）是因其便利性。BRAF突变检测已作为一项重要的辅助检测方法被引入，但LBC样本对其适用性尚未得到充分证实。
将甲状腺切除标本的5份穿刺样本同时制成LBC和细胞块（CS）玻片，在制片后6、9和12个月，使用3组引物对PCR产物分别为72、164和226碱基对（bp）的样本进行BRAF突变检测。此外，对9份经LBC或CS制备并在制片后保存3至5年的临床样本进行BRAF突变检测。
制片后9个月，LBC未能提供质量足以进行PCR的DNA，而CS使用扩增226 bp片段的引物成功完成检测。此外，即使延迟超过1年，CS仍能成功扩增DNA。通过使用引物扩增较短的PCR产物克服了LBC中DNA扩增失败的问题，这表明LBC中发生了DNA降解。然而，在扩增较短片段的引物检测中观察到假阳性或假阴性结果。LBC中使用的保存液种类不影响检测结果。
与酒精固定的CS相比，LBC可能因DNA加速降解而在长期DNA保存方面存在劣势。使用引物扩增较短片段可能有助于减轻LBC中因DNA降解导致的信号损失。
