Cytomorphological factors and BRAF mutation predicting risk of lymph node metastasis in preoperative liquid-based fine needle aspirations of papillary thyroid carcinoma

Objective: Preoperative fine needle aspiration biopsy (FNAB) has become the initial diagnostic method for papillary thyroid carcinoma (PTC). Identification of cytomorphologic factors predicting lymph node metastasis (LNM) is clinically important for determining the appropriate treatment regimen due to the high rate of lymph node involvement in PTC at the time of diagnosis. Hobnail features (HF) have previously been described as potential histomorphologic features in the histological examination of PTC. This study evaluated the value of HF as a predictor of LNM. Study Design: Histologically confirmed FNABs (n = 111) of papillary thyroid microcarcinoma prepared by the liquid-based method were enrolled. Along with other cytomorphologic parameters, HF were evaluated for their value in predicting LNM. Results: Although HF were closely correlated with cytoplasmic vacuoles of tumor cells and background macrophages (p < 0.05), which were considered diagnostic indicators of PTC with cystic changes, HF were only found to be significantly correlated with LNM (p = 0.008). The BRAF ^V660E mutation was not associated with LNM. All combinations including HF were revealed as stronger predictors of LNM (odds ratios: 2.254-2.524, p < 0.05). Conclusions: HF, a distinctive cytomorphologic feature, may be used as a factor predicting LNM in preoperative FNAB of PTC.