Histopathological Patterns of Metastatic Cutaneous Squamous Cell Carcinoma to Intra-Parotid Lymph Nodes and Correlation With Outcomes.

OBJECTIVE: Metastatic cutaneous squamous cell carcinoma (cSCC) to the parotid gland is an uncommon but serious disease process. This study evaluates the histopathological patterns of cSCC metastases to the parotid and correlates with recurrence rates and other clinical outcomes. STUDY DESIGN: This was a retrospective cohort study. SETTING: The study was conducted at a single tertiary care center. METHODS: Cases of cSCC with metastasis to the parotid between 2016 and 2022 were included. The histological slides from the parotidectomy were reviewed to determine the WPOI. The patient's history, operative and surgical pathology reports, and postoperative clinic notes were also reviewed. RESULTS: There was a total of 46 primary tumors. Most cases were located on the pinna, followed by temple and scalp. Patients with WPOI 4/5 were more likely to have received prior adjuvant treatment after initial excision of their primary (P = .035).These tumors were clinically aggressive. 54.3% had perineural invasion (PNI). Histologically, 71.1% were infiltrative with a median WPOI of 3. PNI was the only statistically significant histological factor associated with a higher risk of postparotidectomy recurrence (P = .036). Univariate logistic regression showed that patients with PNI were more likely to have recurrence (OR 8.33, P = .023). CONCLUSION: There were no statistically significant differences in outcomes when comparing WPOI groups. However, PNI, even at a metastatic site, was noted to be a significant risk factor for recurrence in these tumors, supporting prior evidence that PNI is an important factor to consider when determining treatment options in these clinically aggressive malignancies.