Plunging ranula: congenital or acquired?

Otolaryngol Head Neck Surg. 2010 Jan;142(1):104-7.
Plunging ranula: congenital or acquired?
Morton RP, Ahmad Z, Jain P.

Department of Otolaryngology-Head and Neck Surgery, Manukau DHB, Manukau City, New Zealand.
OBJECTIVE: To review our clinical experience with plunging ranula and examine the evidence in support of our impression that plunging ranula has a genetic basis. STUDY DESIGN: Case series with chart review. SETTING: Secondary otolaryngology service. SUBJECTS AND METHODS: Review of the medical records of a clinical series of 80 consecutive plunging ranulas in 77 patients was conducted, with recording of clinical and radiological findings, surgical treatment, and outcome. A literature review using MEDLINE and OLD MEDLINE was performed. RESULTS: The majority of plunging ranulas had no intraoral component on clinical examination, although evidence of mucus extravasation from the sublingual gland could be found both radiologically and histologically in all cases. There were four patients with bilateral plunging ranula and one instance of siblings with unilateral plunging ranula. Maoris and Polynesians comprised more than 82 percent of our cases; this was a significant overrepresentation of these ethnic groups (P < 0.0001). A very strong predominance of cases of Chinese origin was also evident in the literature. CONCLUSION: The clinical findings and the supporting data from the literature, when viewed in light of information relating to the known anatomical anomaly of a dehiscence in the mylohyoid muscle and ectopic sublingual gland lying below the plane of the mylohyoid, appear to support the case for a genetic basis for this unusual clinical entity.