Ranula

A ranula is a fluid-filled cyst that develops under the tongue when salivary glands become blocked or damaged. This condition appears on radiology reports as a well-defined, fluid-containing structure in the floor of the mouth. Ranulas are benign lesions that form when saliva accumulates in tissue spaces rather than draining normally into the mouth.

What Is a Ranula

A ranula is a mucous-filled cyst that forms under your tongue when one of your salivary glands becomes blocked or damaged. The name comes from the Latin word “rana,” meaning frog, because the swelling can make the area under your tongue look like a frog’s throat when inflated. These cysts develop specifically from the sublingual salivary glands, which are located beneath your tongue on either side of your mouth.

The condition occurs when saliva cannot flow normally from these glands into your mouth. Instead of draining properly, the saliva accumulates in the surrounding tissue, creating a balloon-like structure filled with clear or slightly cloudy fluid. This trapped saliva forms what medical professionals call a pseudocyst, since it lacks the true lining that characterizes other types of cysts.

Types of Ranula Cysts

Medical professionals classify ranulas into two main categories based on their location and extent. Understanding these differences helps explain why your doctor might recommend specific treatments or additional imaging studies.

Simple ranulas remain confined to the floor of your mouth, staying above the muscle that forms the base of your oral cavity. These smaller cysts typically appear as soft, bluish swellings directly under your tongue. They feel similar to a water balloon when gently pressed and may change size throughout the day as saliva production varies.

Plunging ranulas represent a more complex form of this condition. These cysts extend deeper into your neck tissues, passing through or around the muscles of your mouth floor. The term “plunging” describes how the cyst appears to dive down into your neck area. These deeper ranulas often require more extensive imaging to fully evaluate their extent and relationship to surrounding structures.

Ranula Symptoms and Signs

The most obvious sign of a ranula is a painless swelling under your tongue. This bump typically appears on one side of your mouth floor and has a characteristic blue or purple tint when viewed through the thin tissue covering. The size can vary considerably, from small pea-sized swellings to larger masses that significantly alter the appearance of your mouth.

Many people notice that their ranula changes size, sometimes becoming more prominent after meals when saliva production increases. The swelling may interfere with normal tongue movement, affecting your speech or making it difficult to eat certain foods. Some individuals report a feeling of fullness or pressure under their tongue, even when the ranula is relatively small.

Unlike infections or other oral conditions, ranulas typically do not cause pain or fever. The surrounding tissues usually appear normal, without the redness or warmth associated with inflammatory conditions. However, if a ranula becomes very large, it may cause discomfort simply due to its size and the pressure it places on surrounding structures.

How Ranulas Appear on Medical Imaging

Radiologists can identify ranulas using several different imaging techniques, each providing specific information about the cyst’s characteristics and location. The appearance of these cysts on medical scans helps doctors distinguish them from other conditions and plan appropriate treatment.

On ultrasound examinations, ranulas appear as well-defined, fluid-filled structures with thin walls. The fluid inside typically shows no internal echoes, appearing black or very dark on the ultrasound screen. This clear appearance helps radiologists differentiate ranulas from solid masses or infected areas that would show different patterns.

CT scans provide excellent detail about ranula size and location, especially for plunging types that extend into the neck. On these images, ranulas appear as smooth, round or oval structures with fluid density similar to water. The cyst walls may be barely visible or appear as thin lines surrounding the fluid collection.

MRI scans offer the most detailed view of ranula characteristics. These cysts typically show high signal intensity on specific MRI sequences, appearing bright white against the darker surrounding tissues. The fluid content and lack of solid components create a distinctive appearance that experienced radiologists recognize immediately.

Ranula Treatment Options

Treatment approaches for ranulas depend on several factors, including the size of the cyst, symptoms it causes, and whether it represents a simple or plunging type. Many small, asymptomatic ranulas require no immediate treatment, as they may resolve spontaneously over time.

For symptomatic ranulas, several treatment options exist. Simple drainage involves inserting a needle to remove the fluid, but this approach often leads to recurrence since the underlying blockage remains. More definitive treatments focus on addressing the source of the problem rather than just the fluid accumulation.

Surgical removal of the affected sublingual gland provides the most reliable long-term solution for recurrent ranulas. This procedure eliminates the source of saliva that creates the cyst, significantly reducing the chance of recurrence. The surgery is typically performed under general anesthesia and involves careful dissection to avoid injury to nearby nerves and blood vessels.

Ranula Complications and Prognosis

Most ranulas remain benign conditions that respond well to appropriate treatment. However, some complications can occur, particularly with larger cysts or those that go untreated for extended periods. Understanding these potential issues helps explain why doctors sometimes recommend treatment even for asymptomatic ranulas.

Large ranulas can interfere with normal mouth function, affecting speech clarity and making it difficult to eat certain foods. In rare cases, very large cysts may partially obstruct the airway, though this complication is uncommon. Plunging ranulas may cause visible neck swelling that some people find cosmetically concerning.

Infection of a ranula, while uncommon, can occur and typically requires antibiotic treatment in addition to addressing the underlying cyst. Signs of infection include increased pain, redness, warmth, and fever. Infected ranulas may require emergency drainage to prevent the spread of infection to deeper neck tissues.

Conclusion

A ranula diagnosis on your radiology report indicates a benign, fluid-filled cyst under your tongue caused by blocked salivary drainage. While the term might initially cause concern, these conditions are generally harmless and treatable when symptoms warrant intervention. Understanding the nature of your ranula, its appearance on imaging studies, and available treatment options allows you to make informed decisions about your care. Most people with ranulas experience excellent outcomes, whether they choose observation for small, asymptomatic cysts or surgical treatment for larger, problematic ones. Working closely with your doctor ensures you receive the most appropriate care for your specific situation.

References

• University of Iowa Protocols – Ranula Radiology: https://medicine.uiowa.edu/iowaprotocols/ranula-radiology (Updated May 2024 – Comprehensive radiology imaging protocols and findings for ranula diagnosis)
• RadioGyan – Ranula Case Study: https://radiogyan.com/cases/ranula/ (Updated May 2024 – Detailed imaging features and diagnostic approach with illustrations)
• PMC – Plunging Ranulas Revisited: A CT Study: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4781766/ (Korean Journal of Radiology 2016 – Research study on pathogenesis and CT findings of plunging ranulas)