Understanding Ranulas: From Simple to Plunging
A ranula is a mucus-filled pseudocyst on the floor of the mouth caused by damage or blockage of a salivary gland duct. The term comes from the Latin word rana, meaning “frog,” due to its appearance. Ranulas are classified as simple (oral) or plunging (cervical or diving). A simple ranula remains in the mouth, while a plunging ranula extends into the neck, distinguished by its movement past the mylohyoid muscle.
The Pathophysiology of a Plunging Ranula
A plunging ranula occurs when a simple ranula expands and ruptures through the mylohyoid muscle, which separates the sublingual space (mouth) from the submandibular space (neck). This allows salivary fluid, usually from the sublingual gland, to enter and dissect into the neck, presenting as a neck mass rather than an oral swelling.
Factors contributing to plunging ranula formation include trauma, salivary duct obstruction, and anatomical variations in the mylohyoid muscle.
Symptoms and Diagnosis
Unlike a simple oral ranula (a bluish cyst under the tongue), a plunging ranula typically appears as a painless, soft, and slow-growing mass in the neck, below the jaw or chin. Sometimes both an oral cyst and a neck mass are present. Large masses can cause difficulty swallowing or, rarely, airway obstruction.
Diagnosing a plunging ranula involves a clinical examination and imaging techniques like ultrasound, CT, or MRI to confirm the cystic nature and extent of the mass. MRI provides superior soft tissue detail. Fine-needle aspiration (FNA) can analyze the cyst fluid for mucus rich in amylase, helping to differentiate it from other neck lesions.
Differential Diagnosis
Distinguishing a benign plunging ranula from other neck masses is crucial. Several conditions can present similarly. The table below outlines key differentiators:
| Condition | Typical Location | Key Features for Differentiation |
|---|---|---|
| Plunging Ranula | Neck (submandibular/cervical) | Communicates with floor of mouth; amylase-rich fluid |
| Cystic Hygroma | Neck, often infiltrative | Multiloculated; watery or milky fluid with cholesterol crystals |
| Branchial Cleft Cyst | Lateral neck | Well-circumscribed; characteristic "beak sign" |
| Dermoid/Epidermoid Cyst | Midline (dermoid) or off-midline (epidermoid) neck/oral floor | Contains keratin; "sack-of-marbles" appearance |
| Thyroglossal Duct Cyst | Midline neck | Moves with swallowing |
Treatment and Prognosis
Surgical intervention is the primary treatment for plunging ranulas to prevent recurrence. The most effective approach is excision of the cyst along with the ipsilateral sublingual gland, the source of the mucus. Draining or removing only the cyst results in high recurrence rates because the gland continues to produce fluid.
Surgical methods include intraoral excision (through the mouth) or cervical excision (external neck incision), depending on the size and location of the mass. Marsupialization, creating a drainage path, is an alternative but less effective for plunging ranulas due to higher recurrence risks.
The prognosis after successful surgical removal of both the cyst and the affected gland is excellent, with minimal recurrence risk. Potential risks include nerve damage, which skilled surgeons minimize. For additional information on oral health conditions, you can consult resources from authoritative health bodies: WebMD on Ranulas.
Conclusion: Seeking Expert Care
A plunging ranula is a rare, treatable condition requiring accurate diagnosis and surgical management, ideally by an otolaryngologist, to prevent recurrence. Understanding its origin from the sublingual salivary gland and how it extends into the neck is key to proper treatment and a successful outcome.
