Plunging ranulas: high-resolution ultrasound for diagnosis and surgical management.

OBJECTIVES: We see a high incidence of plunging ranulas, particularly in Maori and Polynesian populations. We have investigated the usefulness of ultrasound in the diagnosis and management of plunging ranulas and present our findings.

METHODS: Thirty-three new cases were examined over 4 years (June 2004 to October 2008).

RESULTS: High-resolution ultrasound was very successful in determining the extent of the plunging ranula, confirming the cystic nature of the lesion, assessing the status of the mylohyoid muscle (a defect demonstrated in 100% of our cases) and evaluating the sublingual gland for rupture or herniation. Correlation with surgical findings was available for 30 cases. There was excellent ultrasonographic and surgical correlation, particularly with respect to submandibular space cystic collection (29 of 30 cases, 96.7%) and mylohyoid defects (27 of 30 cases, 90%).

CONCLUSIONS: With the considerations of cost, accessibility and the fact that many of our patients are young (median of 20 years), ultrasound is recommended as the preferred examination for plunging ranula.