Parotid tumor size predicts proximity to the facial nerve.

OBJECTIVES/HYPOTHESIS: Parotid surgery mandates that every effort be made to identify and preserve the integrity of the facial nerve. A simple method of predicting the proximity of the nerve to the capsule of the tumor preoperatively may benefit surgical planning and patient counseling. We hypothesized that tumor diameter would be an easily available method to predict nerve proximity to the capsule.

STUDY DESIGN: Retrospective review.

METHODS: Pathology reports for patients undergoing parotidectomy were retrospectively reviewed. Diameter and facial nerve margin positivity were observed and recorded for 109 pleomorphic adenomas, 41 Warthin's tumors, and 106 malignant lesions.

RESULTS: Malignant tumors were most likely to have positive facial nerve margin (63% vs. 53% of pleomorphic adenomas and 37% of Warthin's tumors). A significant difference was found between the diameter of all tumors with a positive facial nerve margin and those with a negative facial nerve margin (P < .001) with margin positivity associated with larger diameter lesions. For all type tumors ≥5 cm, 82.34% had a positive facial nerve margin. Tumors <2 cm were least likely to have a positive facial nerve margin. Logistic regression showed that diameter was correlated with risk of facial nerve margin positivity (odds ratio, 2.66; 95% confidence interval, 1.69-4.18; P < .001).

CONCLUSIONS: These results demonstrate that parotid tumor diameter is both a convenient and functional means of predicting proximity of a tumor to the facial nerve and for preoperative risk stratification. These observations have important clinical implications.