# Ultrasound findings suggestive of microscopic extranodal extension in papillary thyroid carcinoma

## TL;DR

This study identifies ultrasound features that suggest microscopic extranodal extension in papillary thyroid cancer, which is linked to worse outcomes.

## Contribution

The paper introduces specific ultrasound features that correlate with microscopic extranodal extension confirmed by histology.

## Key findings

- Irregular shapes, ill-defined jagged borders, and perinodal hyperechoic rims were more common in lymph nodes with ENE.
- Sensitivity and specificity of these ultrasound features for ENE were 81.0% and 82.6%, respectively.
- Histological analysis confirmed that these ultrasound features correspond to specific types of tumor invasion.

## Abstract

Extranodal extension (ENE) of metastatic carcinoma in patients with papillary thyroid carcinoma (PTC) has been associated with an increased risk of recurrent disease, persistent disease, and disease-specific mortality; however, ultrasound findings suggestive of ENE have not been well established. In this study, we aimed to identify ultrasound findings suggestive of microscopic ENE and validate them histologically.

We retrospectively examined the ultrasound and histological findings of 21 PTC patients with microscopic ENE and 46 without ENE.

Node matting, irregular shapes, ill-defined jagged border, and perinodal hyperechoic rims were observed in 38.1%, 57.1%, 42.9%, and 57.1% of lymph nodes with ENE, respectively, and the frequencies were significantly higher than those without ENE, with p values less than 0.05, 0.0005, 0.0001, and 0.0001, respectively. The sensitivity and specificity of cases with any one of irregular shapes, ill-defined jagged border, and perinodal hyperechoic rims were 81.0% and 82.6%, respectively. Histologically, node matting, irregular shape, ill-defined jagged border, and a perinodal hyperechoic rim correspond to adhesion between lymph nodes, extensive invasion, minimal invasion, and invasion into adipose tissue, respectively.

We would argue that any irregular shape, ill-defined jagged border, and perinodal hyperechoic rim can be accepted as findings indicative of microscopic ENE.