Peer Reviewed

Photo Essay

An Atlas of Lumps and Bumps: Part 13

Alexander K. C. Leung, MD1,2—Series Editor • Benjamin Barankin, MD3 • Joseph M. Lam, MD4 • Kin Fon Leong, MD5

1Department of Pediatrics, University of Calgary, Calgary, Alberta, Canada
2Alberta Children’s Hospital, Calgary, Alberta, Canada
3Toronto Dermatology Centre, Toronto, Ontario, Canada
4Department of Pediatrics and Department of Dermatology and Skin Sciences, University of British Columbia, Vancouver, British Columbia, Canada
5Pediatric Institute, Kuala Lumpur General Hospital, Kuala Lumpur, Malaysia

Leung AKC, Barankin B, Lam JM, Leong KF. An atlas of lumps and bumps, part 13. Consultant. 2022;62(2):e33-e35. doi:10.25270/con.2022.01.00005

Dr Leung is the series editor. He was not involved with the handling of this paper, which was sent out for independent external peer review.

Alexander K. C. Leung, MD, #200, 233 16th Ave NW, Calgary, AB T2M 0H5, Canada (

This article is part of a series describing and differentiating dermatologic lumps and bumps. To access previously published articles in the series, visit



A ranula is a large mucus-containing, cyst-like mass caused by extravasation and accumulation of mucus from a major salivary gland (most commonly the sublingual salivary gland) into the surrounding tissue in the floor of the mouth.1-4 The condition can be congenital or iatrogenic.2,5 Congenital ranulas may result from an imperforate salivary duct or ostial adhesion.4 Iatrogenic ranulas may result from trauma to or obstruction of an excretory duct of a major salivary gland.2,6 Because ranulas are lined with granulation tissue instead of epithelium, they are considered a type of pseudocyst.1,4

The prevalence rate of ranulas is 2 cases per 10,000 persons.3,5,6 Individuals in their second and third decades of life are more commonly affected.2,4,7 The sex ratio is approximately equal.2,6 There is no racial predilection.6

Typically, a simple (or intraoral) ranula presents as a slow-growing, thin-walled, translucent to bluish, fluctuant, painless, round or oval swelling in the floor of the mouth that resembles the belly of a frog (Figures 1 and 2).3,5,6 In fact, the term “ranula” is derived from the Latin word “rana,” meaning belly of the frog.4 Large lesions might lead to speech impairment, difficulty with mastication, dysphagia, and rarely, airway blockage and obstructive sleep apnea.2,3

Figure 1. Ranula

Figure 2. Ranula

A plunging (or cervical) ranula occurs when a portion of the sublingual gland herniates through a dehiscence in the mylohyoid muscle with its extravasated mucin into the submandibular and submental space.1,7,8 Typically, a plunging ranula presents as an asymptomatic, fluctuant to soft cervical mass without swelling of the floor of the mouth. The swelling is usually unilateral but may cross the midline.6 A mixed ranula, on the other hand, presents with both intraoral and cervical swelling.1


Mucoceles are the most common mucus cyst occurring in the oral cavity.9,10 The incidence in the general population is estimated to be 0.2.%.6 A mucocele is caused by a traumatic severed or blocked duct of a minor salivary gland.6,11,12 A traumatic severed duct of a minor salivary gland is most often caused by lip biting during chewing, habitual lip biting, or accidental injury to the lip.6,9,13 This leads to extravasation and accumulation of mucin in submucous tissue, referred to as an extravasation mucocele.10 The extravasated mucin is surrounded by condensed connective tissue with a variable amount of inflammation.10,14 No epithelial lining is present.15 The lower lip is the most frequent site of the extravasation cyst because it is the area most often susceptible to trauma.13,16 A retention mucocele, on the other hand, results from obstruction of the duct of a minor salivary gland.10,17 The obstruction may be caused by epithelial proliferation, trauma, or a sialolith.18,19 The trapped mucus is lined by columnar or cuboidal ductal epithelium.14 Approximately 90% of mucoceles are extravasation mucoceles and the remaining 10% retention mucoceles.20

Mucoceles affect patients of all ages with peak incidence in the first and second decades of life.10,20 Both sexes are equally affected.15,17,20 There is no racial predilection.19

Typically, a mucocele, irrespective of its etiology, presents as an asymptomatic, fluctuant, tense, well-circumscribed, dome-shaped swelling or nodule on the mucosal surface of the lip (Figures 3 and 4).10,16,21 More than 70% of cases occur on the lower lip.22 Less commonly, the mucocele occurs on the upper lip and buccal mucosa. The size of the lesion ranges from a few millimeters to a few centimeters in diameter.18 The color ranges from deep blue to pink (the color of normal mucosa).15,20,21 A mucocele may fluctuate in size and rupture spontaneously.19 Lesions are usually solitary but can be multiple (Figure 5).23

Figure 3. Mucocele

Figure 4. Mucocele

Figure 5. Mucocele

Occasionally, mucoceles may occur on the floor of the mouth, soft palate, hard palate, and tongue.12,20,22,24 The occurrence on the tongue accounts for approximately 2% of cases.25 Rarely, a mucocele may arise on the ventral surface of the tongue and is known as mucocele of the gland of Blandin-Nuhn.14,26 The glands of Blandin-Nuhn are located in the anterior ventral surface of the tongue.14,16,20,27 These glands are arranged in a mass with a horseshoe shape and covered by thin mucous membrane.14,16 In most cases, a mucocele of the gland of Blandin-Nuhn results from a self-inflicted bite wound.16,27 The lesion is usually less than 1 cm in diameter. Rapid onset, fluctuation in size, bluish discoloration and fluid-filled consistency are characteristic.25 A superficial mucocele, a rare subtype of the mucocele of the gland of Blandin-Nuhn, may present as a translucent fluid-filled vesicle or cyst (Figure 6).28,29 The lesion ruptures easily and may leave a slightly painful erosion, which usually heals within a few days.

Figure 6. Mucocele

The diagnosis of oral mucoceles is mainly clinical. Depending on the size and location, a mucocele can become cosmetically unsightly.9 A mucocele may persist for weeks or months before it ruptures spontaneously. Recurrence is common and may lead to fibrosis.10


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