Minimum fascia tumor distance for selection of extracapsular dissection for benign parotid tumors: A preliminary study

Objective: There is increasing literature supporting the use of extracapsular dissection (ECD) for the treatment of select superficial lobe parotid tumors, though no objective criteria for selection has been proposed. Prior studies have suggested the minimum distance between the parotideomasseteric fascia and the tumor edge or minimum fascia-tumor distance (MFTD) as a useful measurement for the identification of superficial parotid tumors. The objective of this study is to demonstrate the utility of the minimum fascia-tumor distance in selecting candidates for extracapsular dissection of benign parotid tumors. Methods: This is a retrospective case-control study at a tertiary academic otolaryngology clinic. Twenty-three patients with prior surgical excision of benign parotid tumors that underwent surgeon-performed ultrasonography prior to excision of tumor were identified. Ultrasound images were reviewed and the minimum fasciatumor distance was recorded and categorized by less than 3 mm or as 3 mm or greater. The primary outcome was successful completion of extracapsular dissection versus more extensive resection. Results: Thirteen patients had a minimum fascia-tumor distance less than 3 mm; eleven of thirteen (84.6%) successfully underwent extracapsular dissection. Ten patients had a minimum fascia-tumor distance of 3 mm or greater; one of ten (10%) successfully underwent extracapsular dissection. A minimum fascia-tumor distance less than 3 mm was sensitive, specific, and accurate in predicting successful ECD at 91.7%, 81.8%, and 87.0% respectively (OR 49.5, 95% CI 3.4-573.2). Conclusion: Minimum fascia-tumor distance may be a useful measurement in identifying candidates for removal of benign parotid tumors with extracapsular dissection.