Modified Transverse-Vertical Gross Examination: a Better Method for the Detection of Definite Capsular Invasion in Encapsulated Follicular-Patterned Thyroid Neoplasms

The diagnosis of encapsulated follicular-patterned thyroid carcinoma (EFPTC) is challenging, and the detection of capsular invasion and/or vascular invasion is essential in distinguishing benign lesions from malignant lesions. In this study, we present a modified transverse-vertical gross examination method with additional vertical cuts at the upper and lower ends of thyroid nodules. In addition, we compared the clinicopathological characteristics of patients with EFPTC between conventional and modified methods. The diagnostic rate of follicular thyroid carcinoma and invasive encapsulated follicular variant of papillary thyroid carcinoma was higher with the modified method (p = 0.003 and p = 0.028, respectively). Furthermore, the paraffin block number and the number of capsular invasion per centimeter were significantly higher with the modified method (p < 0.001 and p = 0.007, respectively). However, vascular invasion was not significantly different between the two methods (p = 0.771). The possibility of identifying capsular invasion was around two times higher with the modified method (odds ratio = 1.91, 95% confidence interval = 1.20–3.07, p = 0.007). A total of 38 samples (23%) in the modified transverse-vertical group had capsular and/or vascular invasion in the additional vertical cuts of the upper/lower ends of the tumor. Our modified transverse-vertical gross examination method was more effective than the conventional transverse examination method for the detection of capsular invasion in EFPTC. This modified gross examination method might allow a better differential diagnosis among various encapsulated micro-follicular proliferative lesions.