Risk of Lymph Node Metastasis in Papillary Thyroid Microcarcinoma: Predictive Finding of Ultrasonography

Shin, Hwa Seon; Kim, Ji Hoon; Na, Dong Gyu

Abstract

PURPOSE
The purpose of this study is to suggest predictive ultrasonographic finding of papillary thyroid microcarcinoma (PTMC) with lymph node metastasis (LNM), compared to PTMC without LNM.
MATERIALS AND METHODS
This study included 93 patients (79 women, 14 men; mean age 46.0 +/- 10.6 years) with surgically proven PTMC. Twenty patients had LNM and 73 patients did not have LNM on surgical specimens. The following ultrasonographic characteristics were evaluated: tumor location, size, shape, echogenicity, margin, presence of calcification, and presence of capsular abutment. Univariate analysis and multivariable stepwise logistic regression analysis were performed for comparison of these characteristics in regard to the presence of LNM in order to determine predictors of LNM.
RESULTS
Two factors were significantly related to LNM: presence of capsular abutment (p = 0.0011) and tumor size (cutoff value: > or = 5 mm, p = 0.0058). Lateral lymph node metastasis (LLNM) showed a significant association with macrocalcification (p = 0.015), presence of capsular abutment (p = 0.0104), tumor size (cutoff value: > or = 7 mm, p = 0.002), and upper location of thyroid nodule (p= 0.0255). Presence of capsular abutment was an independent predictive factor for LNM (Odds ratio: 14.83, p = 0.010). Tumor size was an independent predictive factor for LLNM (Odds ratio: 2.102, p = 0.010).
CONCLUSION
Presence of capsular abutment and tumor size are important ultrasonographic predictors for LNM or LLNM in patients with PTMC.