Ultrasound in the diagnosis and differential diagnosis of enoral and plunging ranula: a detailed and comparative analysis

Abstract

Purpose: To develop sonographic criteria for ranula that to allow rapid and precise diagnosis, differentiation between enoral (ER) and plunging ranula (PR), and differential diagnosis from other competing pathologies in this region.

Methods: Patients who presented with or were referred with ranula between 2002 and 2022 were assessed in a retrospective study. After clinical investigation, ultrasound examinations were performed in all cases. Several sonographic parameters describing the echotexture, shape and size of ranulas, their relationship to important surrounding anatomical landmarks and the characteristic spreading pattern of ERs and PRs were elaborated and evaluated.

Results: 207 ranulas were included (82.12% ERs and 17.87% PRs). The ranulas were all in close anatomical relationship to the sublingual gland (SLG) and mylohyoid muscle (MM). The echo texture was hypoechoic to anechoic in 97.6% of the lesions. In comparison with ERs, PRs were larger and irregular in shape significantly more often (P = 0.0001). There were significant differences between ERs and PRs in their exact location relative to the SLG (superficial, deep, anterior, each P = 0.0001; posterior, P = 0.03) and level of the MM (above, below, above and below, P = 0.0001 each). The exact extent and plunging pattern were depicted in all PRs, but naturally in none of the ERs.

Conclusions: The ultrasound criteria developed in this study, confirming previously published results, indicate that ultrasound is an excellent diagnostic tool for diagnosing ranula and differentiating between ERs and PRs.

Keywords: Diagnosis; Differential diagnosis; Enoral; Plunging; Ranula; Ultrasound.

Fig. 1

a–b Anterior a and lateral transection view b view of the floor of the mouth shows an ER in a 11-year old female patient (size 31 × 27x35mm): the ER (SOL) is located anterior, superficial and deep to the SLG and above the intact MM (orange arrows) in the floor of the mouth. The internal structure is characterized by a moderate hypoechoic tissue pattern, the echogenicity is sludge-like due to a thickened mucous secretion. GHM geniohyoid muscle, DM digastric muscle, MM mylohyoid muscle, SOL space occupying lesion/ER, SLG sublingual gland, TONG tongue, M mandibula, Level IB links Level IB left side

Fig. 2

a–b Anterior (a) and lateral transection view (b) of the floor of the mouth showing a PR with a hypoechoic tissue pattern with an irregular shape in a 12 year old female patient (size 33 × 31 × 55 mm): the PR (SOL) is located anterior, superficial and deep to the SLG and above the intact MM (a, green arrow) in the (anterior part of the) floor of the mouth. The PR is also posteriorly located above the MM and is extending beyond the posterior border of the MM (a, orange arrow). The huge plunging part of the ranula, extending into the submandibular space, is indicated (b, blue arrow). MGH geniohyoid muscle, DM digastric muscle, MM mylohyoid muscle, SOL space occupying lesion/PR, SLG sublingual gland, SMG submandibular gland

Fig. 3

a–c Anterior transection view of the floor of the mouth native (a) and with low-flow doppler sonography (b) shows a PR in a 23 year old female patient (size 30 × 27x44mm): the moderate hypo-echoic and irregular shaped PR (SOL) is located anterior and deep to the SLG and partially above and partially below the MM in the anterior part of the floor of the mouth and is reaching to the submandibular space (a, orange arrow). The low-flow doppler sonography shows that the PR is perfused also in the region of the plunging through the hiatus of the MM (diameter 23.3 mm, orange arrow, b). Video 1 of the supplemental material is corresponding to this imaging. Lateral transection view (c) with low-flow doppler sonography shows that the PR (SOL) is partially perfused, in particular in the region of the plunging through the hiatus of the MM (diameter 26.1 mm) and is extending to the submandibular space (orange arrow, C). A puncture of the SOL revealed secretion characteristic for ranula. To exclude any combined pathology (e.g. PR and vascular malformation), MRI was also indicated. Video 2 of the supplemental material is corresponding to this imaging. GHM geniohyoid muscle, DM digastric muscle, MM mylohyoid muscle, SOL space occupying lesion, SLG sublingual gland, SMG submandibular gland, TONG tongue, M mandible

Fig. 4

a–b Transection (a) and longitudinal view (b) of the floor of the mouth shows a PR (SOL) in the left floor of the mouth in a 69 year old male patient (size 48 × 18 × 23 mm): The SOL (PR) shows a hypo-echoic tissue texture and is irregular shaped. The anatomical structure of the MM shows no continuity due to a hiatus (orange arrow, A). The PR located deep to the SLG and there is nearly no contact to it. The PR (SOL) is located almost totally below the MM in the submandibular space nearby the SMG and below the niveau of the mandible (orange arrow, B). DM digastric muscle, MM mylohyoid muscle, SOL space occupying lesion, SLG sublingual gland, SMG submandibular gland, M mandible, TONG tongue, Level IB links Level IB left side

Fig. 5

Transection view of the posterior submandibular space shows space occupying lesion dorsal to the tongue and the tonsil region in the transition to the PPS in a 34 year old male patient presenting with 2 recurrent ranulas on the left side (size of ranula located in the PS 37 × 18 × 28 mm). One PR (not depicted) was located primarily in the SS and the second in the PS. The hypo-echoic and regular shaped SOL is shown dorsal to the TONG and tonsil nearby the pharynx within the PS. The orange arrow indicates the reverberations effect caused by the air within the pharyngeal lumen. Video 3 of the supplemental material is corresponding to this imaging. SOL space occupying lesion, TONG tongue, PH pharynx, PS parapharyngeal space, SS submandibular space, Li left side