A ranula is a benign swelling that develops on the floor of the mouth beneath the tongue. This growth is a fluid-filled pocket that arises when saliva leaks out of a damaged salivary gland. The term “ranula” comes from the Latin word rana (frog), because the swelling often resembles the translucent underbelly of a frog. While typically painless, a ranula can grow large enough to cause noticeable symptoms and may require professional attention.
The Characteristic Appearance of an Oral Ranula
The most distinctive feature of an oral ranula is its appearance as a smooth, dome-shaped swelling located unilaterally on the floor of the mouth. This lesion is often described as translucent and typically has a pale blue or bluish color due to the fluid close to the surface of the oral mucosa. This bluish hue results from light filtering through the thin overlying tissue and reflecting off the accumulated fluid beneath.
The texture of the ranula is typically soft and fluctuant, meaning it feels like a fluid-filled balloon when gently pressed. The size is variable, ranging from a small, pea-sized bump to several centimeters in diameter. A large ranula can cause the tongue to be noticeably elevated and displaced.
A large ranula may interfere with normal mouth functions, such as speaking, chewing, or swallowing (dysphagia). The lesion is generally painless unless it becomes secondarily infected. If the ranula is located deeper within the connective tissues, the blue, translucent characteristic may be less obvious, and the swelling might appear pinkish or the same color as the surrounding mucosa.
How a Ranula Forms
A ranula is technically a mucocele, or mucus extravasation phenomenon, because it lacks a complete epithelial lining. This structure originates almost exclusively from the sublingual salivary gland, the smallest of the major paired salivary glands. Formation begins when a duct of the sublingual gland is disrupted or blocked, often due to minor trauma or injury to the floor of the mouth.
When the duct is compromised, the saliva (primarily mucus) leaks into the surrounding connective tissue space instead of draining into the mouth. This accumulated mucus triggers a localized inflammatory response. The body attempts to wall off this pooled fluid, forming a pseudocyst that results in the soft, dome-shaped swelling.
While trauma is a common suspected cause, ranulas can also form without a clear preceding injury. The continuous secretion of the sublingual gland contributes to the ongoing fluid accumulation and enlargement of the ranula.
Distinguishing Between Simple and Plunging Ranulas
Ranulas are categorized into two main types based on their anatomical location: simple (oral) and plunging (cervical). The simple ranula is the most common form, confined entirely to the sublingual space above the mylohyoid muscle. This type is the classic bluish, translucent swelling that can push the tongue upward.
A plunging ranula, sometimes called a diving or cervical ranula, occurs when the accumulated mucus extends beyond the floor of the mouth. This happens when the fluid penetrates the mylohyoid muscle and migrates into the neck region. The visual presentation of a plunging ranula is a firm, non-tender swelling in the upper neck, specifically the submandibular area.
The oral component of a plunging ranula may be small or absent, meaning the swelling is only visible externally in the neck. The neck mass is typically larger than its oral counterpart, sometimes reaching four to ten centimeters in size. While oral ranulas cause issues like difficulty with speech, plunging ranulas may manifest with a sensation of neck tightness but are usually otherwise asymptomatic.
Diagnosis and Management Options
The diagnosis of a ranula is often made through a clinical examination due to its characteristic appearance and location. The healthcare provider typically assesses the swelling’s location, color, and consistency, often palpating it to determine its soft, fluctuant nature. For unclear cases, or to assess the extent of a plunging ranula, imaging studies may be used.
High-resolution ultrasound helps evaluate the cystic nature of the mass. Computed tomography (CT) or magnetic resonance imaging (MRI) is often used for larger or plunging ranulas. These techniques help differentiate a ranula from other neck masses, such as a dermoid cyst or an abscess.
The chosen management approach depends primarily on the size and type of the ranula. Small, asymptomatic ranulas may simply be observed, as some resolve spontaneously. For larger or persistent lesions, surgical management is usually recommended.
Surgical Procedures
One common procedure is marsupialization, which involves unroofing the cyst and stitching the edges to keep it open, allowing for continuous drainage. A more definitive treatment to prevent recurrence involves surgically removing the entire sublingual gland on the affected side, which eliminates the source of the mucus leakage.