Plunging Ranulas and Prevalence of the “Tail Sign” in 126 Consecutive Cases

Abstract

Objectives Plunging (or diving) ranulas are extravasation pseudocysts arising from the sublingual gland that present as soft submandibular swelling. The “tail sign” has been widely reported as pathognomonic for their diagnosis. It is described as a smooth tapering comet‐shaped unilocular fluid mass with its “tail” in the collapsed sublingual space (SLS) and its “head” in the posterior submandibular space. This sign is based on the premise that extravasated saliva from the sublingual gland in the SLS escapes and plunges, over the posterior edge of the mylohyoid muscle into the submandibular space. Therefore, some fluid must be present in the posterior SLS in almost all patients with plunging ranulas. This study aimed to determine the frequency of fluid seen with ultrasound (US) in the posterior SLS to corroborate the tail sign. Methods A total of 126 consecutive cases of surgically proven plunging ranulas were investigated with US over 13 years. The findings were reviewed retrospectively for the prevalence of fluid in the posterior SLS. Results Thirteen patients (10.3%) showed SLS fluid on US images. Most showed fluid extension through a mylohyoid dehiscence. Only 2 patients (1.6%) showed fluid within the posterior SLS, and 1 patient alone in this entire study showed all of the components of the classically described tail sign. Conclusions This largest ever radiologic study showed low prevalence of the tail sign in 2 of 126 patients. A mylohyoid dehiscence was the more common route for extravasation. Absence of the tail sign does not exclude the diagnosis of a plunging ranula.

Bilateral Plunging Ranulas in South Auckland: Evidence for a Genetic Basis

“…However, this ethnic makeup enabled the material to be obtained, which led to the realization that there can be a genetic basis for plunging ranula and bilateral plunging ranulas. 2,3,6,19 CONCLUSION All patients with a unilateral plunging ranula should be advised of the potential for developing contralateral disease, and this should be emphasized in patients of Pacific Island, Maori, and Asian descent. 4…”

“…However, these ethnicities were even more overrepresented in our data, with 96.2% of all patients in our case series being of Maori, Pacific Island, or Asian descent, showing that our results do not simply represent the ethnic makeup of our catchment area. However, this ethnic makeup enabled the material to be obtained, which led to the realization that there can be a genetic basis for plunging ranula and bilateral plunging ranulas 2,3,6,19 …”

“…Commonly, a mylohyoid muscle dehiscence is also associated with SLG herniation. 1,2 Plunging ranulas have an age-adjusted incidence in New Zealand of 2.6 per 100 thousand person-years; typically occur in the second and third decades of life; and appear to be more common in patients of Pacific Island, Maori, and Asian descent. 3,4 Bilateral plunging ranulas are rare, with only 25 cases reported in the literature.…”

“…They can be synchronous or metachronous, with metachronous plunging ranulas presenting up to 2.5 years apart. 1,2,[5][6][7][8][9][10][11][12][13][14] Due to the apparent association of Pacific Island, Maori, and Asian descent with plunging ranula, we decided to investigate the possibility of such an association with bilateral plunging ranulas and whether it could have an effect on treatment and prognosis.…”

“…A plunging ranula generally occurs when saliva escapes from the sublingual space into the submandibular space via a mylohyoid muscle dehiscence; it infrequently occurs around the posterior border of the mylohyoid muscle. Commonly, a mylohyoid muscle dehiscence is also associated with SLG herniation 1,2 . Plunging ranulas have an age‐adjusted incidence in New Zealand of 2.6 per 100 thousand person‐years; typically occur in the second and third decades of life; and appear to be more common in patients of Pacific Island, Maori, and Asian descent 3,4 .…”