Lymph node metastasis development in external ear squamous cell carcinoma follow-up: the role of T stage, tumor grade, and anatomical subsites.

Purpose: Lymph node metastasis (LNM) significantly impacts prognosis in external ear squamous cell carcinoma (SCC). Identifying high-risk patients remains a challenge due to the lack of standardized criteria for elective neck dissection (END). This study aims to evaluate predictive factors for LNM in external ear SCC.

Methods: a retrospective analysis of 176 patients with T1-T3, N0 external ear SCC who underwent surgical excision between 2015 and 2019 was conducted. Patients were stratified by tumour subsite (auricle, external auditory canal, retroauricular, and preauricular regions). Histopathological parameters, including tumor size (T), depth of invasion (DOI), perineural invasion (PNI), perivascular invasion (PVI), cartilage invasion, and tumor grade, were analysed for association with LNM. Statistical analyses included univariate and multivariate logistic regression models.

Results: LNM occurred in 5.7% (n = 10) of patients, with metastases appearing within an average of 7.1 months post-surgery. T3 tumours had a significantly higher LNM rate (p < 0.05). The preauricular region was the most frequent metastatic subsite (p = 0.001). Poorly differentiated tumours (G3/G4) were strongly associated with LNM (p = 0.001). DOI and cartilage invasion were not independent predictors. The Brigham and Women's Hospital (BWH) classification system demonstrated superior risk stratification compared to NCCN and AJCC-8.

Conclusion: T3 stage, preauricular location, and high tumour grade are significant predictors of LNM in external ear SCC. The findings support the need for individualised risk stratification, with consideration of END in high-risk cases. Future studies should incorporate molecular markers to refine metastatic risk assessment.