Could Pretreatment Computed Tomography Imaging Accurately Predict the Pathological Diagnosis of Lymph Node Involvement in Thymic Epithelial Tumors?

Background: Thymic epithelial tumors (TETs) are the most common primary malignancies of the anterior mediastinum. Initial treatment planning for TETs is based on staging determined through computed tomography (CT) imaging. This study aimed to demonstrate that pretreatment CT imaging can provide critical insights into lymph node (LN) metastasis in TETs, potentially guiding surgical decisions. Methods: Thirty patients with TETs treated at National Taiwan University Hospital from 2008 to 2023 were included. Three radiologists independently evaluated the pretreatment CT scans for LN metastasis, with findings validated against postoperative pathology reports. The study assessed the correlation between radiological and pathological LN findings, including criteria such as LN size, density, and morphology. Results: In a cohort of 30 TET patients, 43% were male, with an average age of just over 57 years. All patients underwent N1 LN dissection, and three also received N2 dissections. Pathological results confirmed LN metastasis in four cases (two thymoma B3, two thymic carcinoma), and 40% of patients were Masaoka-Koga stages III-IVb. Three experienced radiologists independently reviewed pretreatment CT scans and identified all four pathology-confirmed metastatic cases, yielding 100% sensitivity and negative predictive value (NPV) in this cohort. However, these findings should be interpreted cautiously because only four patients had pathologically confirmed LN metastasis. Conclusions: Pretreatment CT assessment may provide useful information for the evaluation of suspicious LN involvement in TETs and may assist preoperative planning. However, given the small number of metastatic cases, these findings should be considered preliminary, and further validation in larger, multicenter studies are required.