Ranula is a mucus retention cyst or mucus extravasation pseudocyst arising from the sublingual salivary gland, located in the floor of the mouth. It has two forms: simple (oral) ranula is confined to the floor of the mouth; plunging (diving) ranula extends through the mylohyoid muscle into the submandibular and submental spaces. Plunging ranula may present as a neck mass in the submandibular region and is included in the differential diagnosis of cystic neck masses. Histologically, it may be a true cyst lined by epithelium (retention cyst) or a pseudocyst without epithelial lining (extravasation cyst); the pseudocyst form is much more common (90%+). Peak incidence occurs in young adults, slightly more common in females. Oral ranula appears as a blue-translucent, fluctuant, painless swelling — the name 'ranula' (= little frog) comes from this appearance. Plunging ranula presents as a painless, compressible mass in the submandibular/submental region.
Age Range
10-40
Peak Age
25
Gender
Equal
Prevalence
Uncommon
The imaging findings of ranula are based on leakage of mucinous salivary secretion from the sublingual gland or ductal obstruction. In the extravasation (pseudocyst) form, rupture of the sublingual gland duct due to trauma or obstruction causes mucinous saliva to leak into surrounding soft tissues; inflammatory granulation tissue forms the pseudocyst wall. In plunging ranula, mucinous fluid passes through the posterior free edge of the mylohyoid muscle or through a mylohyoid defect into the submandibular and submental spaces — a thin connecting channel known as the 'tail sign' shows the passage from the sublingual space. This mucinous fluid contains high protein and glycoprotein and shows higher density than simple fluid on CT, hyperintensity on T1 MRI. Thin wall and homogeneous fluid content reflect the simple cystic structure. In infected ranula, the wall thickens and inflammatory changes develop in surrounding tissues.
The pathognomonic imaging finding of plunging ranula is the 'tail sign' — a thin, T2 hyperintense tail extension from the sublingual space passing through the posterior free edge or defect of the mylohyoid muscle into the submandibular space. This finding distinguishes plunging ranula from other submandibular cystic masses.
On T2-weighted sequences, ranula appears as a thin-walled cystic lesion with markedly hyperintense signal. Simple ranula is confined to the sublingual space. Plunging ranula extends through the mylohyoid muscle into the submandibular and/or submental space — a thin connecting channel known as the 'tail sign' shows the passage from the sublingual space and is a pathognomonic finding. MRI is the most valuable modality for complete anatomical mapping of plunging ranula. T2 signal may differ slightly from simple serous fluid — slightly lower T2 is possible due to mucinous content but generally markedly hyperintense. In infected ranula, the wall thickens and T2 hyperintense edema is observed in surrounding tissues.
Report Sentence
A T2 hyperintense cystic lesion extending from the sublingual space through the mylohyoid muscle into the submandibular space is identified in the floor of mouth ('tail sign' positive); consistent with plunging ranula.
On T1-weighted sequences, the fluid content of ranula generally shows mildly hyperintense signal — different from simple serous fluid (T1 hypointense). This finding reflects the proteinaceous nature of the mucinous fluid. In infected or hemorrhagic ranula, T1 hyperintensity may be more prominent. The thin cyst wall shows minimal enhancement on T1. On post-contrast series, rim enhancement is thin and smooth — thick or irregular rim enhancement suggests infection or tumor.
Report Sentence
The fluid content of the cystic lesion shows mildly hyperintense signal relative to simple fluid on T1-weighted sequences; consistent with mucinous content and supporting ranula.
On contrast-enhanced CT, plunging ranula appears as a thin-walled, low-density cystic mass in the submandibular space. Cyst fluid density is slightly higher than simple fluid (10-25 HU — mucinous content). 'Tail sign' — a thin tail extension from the sublingual space crossing the mylohyoid muscle — is also visible on CT and is pathognomonic for distinguishing plunging ranula from other submandibular cystic masses (thyroglossal duct cyst, branchial cleft cyst, dermoid). The thin, smooth cyst wall shows minimal enhancement. In infected ranula, wall thickening, peripheral enhancement increase, and surrounding soft tissue edema are observed.
Report Sentence
A thin-walled, low-density cystic mass is identified in the submandibular space, with a thin tail extension (tail sign) from the sublingual space crossing the mylohyoid muscle; consistent with plunging ranula.
On B-mode ultrasonography, simple ranula appears as an anechoic or low-echo, thin-walled, well-defined cystic lesion in the floor of the mouth. Posterior acoustic enhancement is prominent. Plunging ranula is seen as a similar cystic structure in the submandibular space. US can demonstrate extension from the sublingual space along the mylohyoid muscle but may not show the tail sign as clearly as MRI and CT. In infected ranula, internal echoes increase, wall thickens, and edema is observed in surrounding tissues. US is useful for FNAB guidance and post-treatment follow-up.
Report Sentence
A thin-walled, anechoic cystic lesion with posterior acoustic enhancement is identified in the floor of mouth/submandibular space; consistent with ranula.
On DWI, ranula does not show diffusion restriction — ADC values are high (>2.0 × 10⁻³ mm²/s). This finding is critical for distinguishing ranula from infected cystic lesions (abscess — low ADC) and solid tumors (low ADC). In infected ranula, purulent content may show diffusion restriction (ADC decreases). T2 shine-through effect may create hyperintensity on DWI at high b-values; correlation with ADC maps is mandatory.
Report Sentence
The cystic lesion does not show diffusion restriction with high ADC values; consistent with uncomplicated ranula and abscess is excluded.
Criteria
Confined to sublingual space, not crossing mylohyoid muscle.
Distinct Features
Blue-translucent fluctuant swelling in floor of mouth, clinical diagnosis usually sufficient, marsupialization treatment.
Criteria
Extending through mylohyoid muscle into submandibular/submental space.
Distinct Features
Presents as neck mass, tail sign positive, treatment with sublingual gland excision, MRI mandatory preoperatively.
Criteria
Ranula with secondary bacterial infection.
Distinct Features
Wall thickening, surrounding edema, DWI diffusion restriction may occur, pain, fever. May mimic abscess.
Distinguishing Feature
Branchial cleft cyst is periauricular/parotid located, no tail sign, may relate to external auditory canal. Ranula is sublingual origin, tail sign positive, floor of mouth location.
Distinguishing Feature
Sialolithiasis shows hyperdense calculus in the duct and obstructive ductal dilation. Ranula is cystic, no stone, tail sign positive.
Distinguishing Feature
Acute sialadenitis shows diffuse gland enlargement and enhancement increase. Ranula is focal cystic lesion, gland parenchyma normal.
Urgency
routineManagement
surgicalBiopsy
Not NeededFollow-up
Basit ranula: marsupializasyon veya sublingual bez eksizyonu. Dalıcı ranula: sublingual bez eksizyonu ile birlikte kist eksizyonu (bez çıkarılmazsa rekürrens yüksek). MR preoperatif planlama için zorunlu. Aspirasyon tek başına yetersiz — rekürrens oranı yüksek.In ranula treatment, excision of the sublingual gland is critical for preventing recurrence. Simple ranula can be treated with marsupialization (opening the cyst and marginal suture) but recurrence can reach 60-70%. Surgical treatment combined with sublingual gland excision reduces recurrence to <5%. In plunging ranula, sublingual gland excision is mandatory — cyst aspiration or submandibular cyst excision alone without removing the gland is insufficient. MRI is mandatory preoperatively for complete anatomical mapping of plunging ranula. OK-432 (picibanil) injection can be used as sclerotherapy as a surgical alternative.
Treated with sublingual gland excision. Marsupialization carries recurrence risk.