Abstract: Objective To establish a pathology-based microvascular invasion (MVI) risk stratification system for hepatocellular carcinoma (HCC), analyze the pathological invasion characteristics and immune microenvironment differences among different risk levels, and assess their association with postoperative prognosis. Furthermore, this study aimed to evaluate the independent prognostic value of MVI risk stratification and provide a reference for postoperative risk assessment and individualized treatment. Methods Clinical and pathological data of 81 patients with HCC who underwent curative resection in the First Affiliated Hospital of Henan Medical University were retrospectively analyzed. According to the number, distribution, and morphological characteristics of MVI, patients were categorized into three groups: M0 (n=53), M1 (n=18), and M2 (n=10). Pathological invasive behaviors, postoperative recurrence patterns, and immune infiltration characteristics were compared among different MVI risk levels. Recurrence-free survival was analyzed using the Kaplan-Meier method. Results With increasing MVI risk stratification, invasive pathological features of HCC progressively intensified. The M2 group showed significantly lower capsule integrity and markedly higher proportions of moderate-to-poor differentiation, unclear/infiltrative margins, and satellite nodules (P<0.05). Postoperative recurrence analysis revealed recurrence rates of 50.0%, 70.0%, and 90.0% at 6 months, 1 year, and 2 years, respectively, in the M2 group, which were significantly higher than those in the M0 and M1 groups. In the M2 group, the median recurrence time was markedly shorter, re-resection rates decreased, and 1-year mortality after recurrence increased (P<0.05). Regarding the immune microenvironment, high-risk MVI patients exhibited significantly reduced CD4⁺, CD8⁺, and NK cell infiltration, whereas Treg, TAM, and MDSC levels increased progressively (P<0.05), indicating an immunosuppressive phenotype. Kaplan-Meier analysis showed significant differences in recurrence-free survival among the risk groups (log-rank test, P<0.001). Conclusion The pathology-based MVI risk stratification system effectively reflects the invasive characteristics of HCC and differences in the immune microenvironment and serves as an independent predictor of postoperative recurrence and survival. Compared with traditional binary MVI assessment (presence/absence), this stratification system provides a more refined approach and may offer important guidance for postoperative risk management, follow-up strategies, and adjuvant treatment decision-making in HCC patients.

Key words: Hepatocellular carcinoma, Microvascular invasion, Pathological features, Immune microenvironment, Prognostic analysis