Pathological characteristics of cervical lymph node metastases in papillary thyroid carcinoma compared with lung adenocarcinoma.

BACKGROUND: US-guided thermal ablation (TA) has shown favorable local control for cervical lymph node metastases (LNM) from papillary thyroid carcinoma (PTC), whereas outcomes appear less favorable for LNM from lung adenocarcinoma (LAC). The pathological basis underlying these differences remains unclear. PURPOSE: To compare the pathological characteristics of cervical LNMs from PTC and LAC, focusing on proliferation- and invasion-related markers, and to explore potential biological factors associated with their distinct clinical behavior. METHODS: In this single-center retrospective study, cervical LNM specimens from patients with PTC or LAC were assessed by immunohistochemistry for Ki-67, PCNA, p53, and MMP-9. Marker expression in tumor cells was compared between groups. RESULTS: A total of 145 patients were included (PTC-N1a, n = 50; PTC-N1b, n = 50; LAC-LNM, n = 45). LAC-related lymph node metastases (LAC-LNM) showed significantly higher Ki-67, PCNA, p53, and MMP-9 staining intensity than both PTC subgroups (all overall P < 0.001). The proportion of MMP-9-positive tumor cells also differed among groups (P = 0.016). Within the PTC cohort, only Ki-67 expression was significantly higher in N1b than in N1a (P = 0.001). After adjustment for age and sex, LAC-LNM remained associated with higher Ki-67, PCNA, and p53 expression and greater MMP-9 staining intensity, whereas the difference in MMP-9-positive tumor cell proportion was no longer significant. CONCLUSION: LAC-LNM exhibited a more proliferative immunophenotype and greater MMP-9 staining intensity than PTC-LNM. These differences may contribute to their distinct clinical behavior.