A ranula is a type of mucocele that forms exclusively on the floor of the mouth, arising from disrupted mucous flow within the sublingual gland or, less commonly, the submandibular (Wharton’s) duct. The name derives from the Latin word for frog (rana), a reference to the dome-shaped swelling’s resemblance to a frog’s translucent underbelly.

Types of Ranula

Ranulas are classified into two forms based on the extent of the lesion:

• Simple (oral) ranula: A superficial, dome-shaped swelling confined to the floor of the mouth, typically appearing blue or translucent because of the thin overlying mucosa.
• Plunging (cervical) ranula: A more complex form in which extravasated mucus dissects through or around the mylohyoid muscle, producing a palpable mass in the neck. This variant is less common but clinically more significant and can be mistaken for a neck abscess or lymph node enlargement.

Clinical Significance

Most ranulas are painless and asymptomatic in early stages, but enlarging lesions can impair speech, swallowing, and tongue movement. On examination, a simple ranula presents as a soft, fluctuant swelling with a characteristic blue hue; spontaneous rupture releases clear or mucoid fluid, though the cyst typically recurs because the underlying glandular source remains intact. A plunging ranula may compress adjacent structures within the sublingual or submandibular space, underscoring the importance of timely evaluation.

Common Causes

Ranulas result from disruption of normal salivary outflow rather than infection. Recognized contributing factors include:

• Trauma to the floor of the mouth from biting, injury, or dental procedures
• Obstruction or rupture of the sublingual gland’s ductal system
• Mucous extravasation following ductal injury
• Congenital ductal anomalies, particularly in pediatric patients

Diagnosis and Treatment

Diagnosis is primarily clinical, though ultrasound or MRI is indicated when a plunging ranula is suspected or the lesion is unusually large. Differentiating a ranula from other floor-of-mouth pathology — including a dermoid cyst, lymphangioma, or salivary gland neoplasm — may require biopsy. The preferred treatment is marsupialization combined with excision of the associated sublingual gland; removing the gland substantially reduces recurrence rates compared with drainage or marsupialization alone.

Any persistent or enlarging swelling on the floor of the mouth warrants prompt assessment by a dental professional or oral and maxillofacial surgeon to confirm the diagnosis and determine the most appropriate intervention.