9-Year-Old Boy With Lump in Floor of Mouth
A 9-year-old boy is seen by his primary care physician for a soft lump in the floor of his mouth. He is brought in for an immediate appointment by his anxious parents, who just became aware of it and are frightened that “it might be cancerous.”
Child looks systemically well and is developmentally appropriate. Dentition normal. Floor of mouth as shown. Abnormal area, when palpated, has a yielding consistency and is not tender; no secretions are expressible from any salivary gland orifice when the area is palpated. No lymphadenopathy in the head or neck.
WHAT’S YOUR DIAGNOSIS?
Answer on next page
Ranula, from the diminutive form of the Latin word for frog, is a contained sac of extravasated seromucous secretion in the floor of the mouth issuing from the sublingual salivary gland. When ranula is asymptomatic, its import lies principally in that it can be confused with other conditions that may be more threatening and that may require a different management approach.
Ranulas are seldom post-traumatic, although they can complicate surgery on the submental area.1 They can wax and wane in a circadian pattern as salivary flow and drainage vary with activity, ingestion, state of wakefulness, and autonomic tone. Such fluctuations may lead the clinician, if unaware of this characteristic, to doubt the history and to construe it as at least inaccurate and perhaps fabricated.
On physical examination, ranulas are almost always found in the floor of the mouth, anteriorly. This location corresponds to the location of the disordered sublingual gland.2-4 Ranulas look blue if the overlying mucosa is thin, but pink if it is thicker. A dome shape and lack of tenderness are characteristic. When ranulas are fluctuant, as this one was, they may raise the specter of contained pus and an abscess, although none of the other features correspond to acute inflammation: with a ranula, the surrounding tissue should not be indurated, hot, tender, or erythematous, although chronic irritation may superimpose slight overlays. The fluctuance that misleads us to think of abscess relies on the mucous content’s having a texture and viscosity similar to that of pus.
Ranulas do not collapse on firm palpation, ie, they cannot be emptied with digital pressure. The telangiectases on the surface in the present case may result from pressure exerted by the expanding mass. Sialagogues such as lemon drops would be expected to swell ranulas because they should increase the inflow of saliva into them, but we have seen no data confirming or refuting this speculation.
NOT STAYING WHERE EXPECTED
In the case presented, a bluish tint is more prominent on the right side of the floor of the mouth, but the lesion bulges upward on the left as well as the right side of the frenulum linguae. Such spreading suggests that although the lesion originated from a right-sided salivary gland, the ranula did not respect tissue planes.
A still more striking false localization occurs when a ranula herniates inferiorly through a defect in the mylohyoid muscle, or behind this muscle, into the neck (Figure 1). Ranulas that protrude below constitute a subset called plunging ranulas.4-8 They can emerge into the submandibular space, in the neck or, in one extraordinary new report, in the thorax.9 Very rarely, the oral origin is not evident. Much more typically, the visible intra-oral element is identical to that of an ordinary nonplunging ranula (Figure 2).
Several major clinical entities are included in the differential diagnosis:
•Mucocele represents the same process of mucous extravasation and rounded containment by an epithelial or connective tissue boundary, but from an origin in a minor salivary gland of the lip. Hence, mucocele is distinguished by location and by the sometimes discernible mucus beneath a thin, membranous overlying cover (Figure 3). In other words, mucocele closely resembles ranula in pathogenesis but not in appearance.
Criteria have been described for definitive diagnosis of ranula by MRI,6 a test that can often be omitted if one feels confident of the clinical diagnosis.
• Oral abscess has been mentioned in regard to fluctuance, above. If doubt persists, aspiration will promptly settle the question: clear, tenacious mucosalivary material is expected from a ranula, frank pus from an abscess cavity. Microscopy and culture of the retrieved material will then confirm and corroborate the diagnosis.
• Intra-oral hematoma usually follows early after oral surgery or any trauma, except in the patient who is profoundly hypocoagulable. There is often visible damage to the overlying mucous membrane. A stinging tenderness is often present. Fluctuance in this setting results from nonclotted blood, whereas a rubbery texture in one of these will imply coagulation. Sublingual hematoma following minor trauma has been described in accidental overdose of antithrombotic medication.10
• Intra-oral hemangioma can assume the same spectrum from purple to reddish, but it sometimes flattens on digital pressure. One is, of course, best advised not to aspirate a putative hemangioma! Closely related is the (horribly misnamed) pyogenic granuloma, which is actually an aberrant collection of microvessels that has nothing whatever to do with pus formation (pyogenic) or with granulomatous inflammation.
NEOPLASMS TO CONSIDER
Besides the benign collections of blood vessels mentioned above, there are some more ominous prospects:
• Squamous carcinoma shares a predilection for the floor of the mouth, but should manifest erythroplasia or, in the advanced stage, white surface discoloration and irregularity.
• Mucus-producing adenocarcinoma and mucoepidermoid carcinoma1 can delay diagnosis if one notes only the mucous product of the tumor and mislabels the case as a ranula. When the oral surgeon unroofs a ranula, it is imperative that he or she palpate the base for a button of solid tissue, which might represent a tumor, and perform a biopsy for histopathologic study.
• Kaposi sarcoma lesions, seen in the mouth of HIV-infected persons, can assume a blue-purple color. They can be covered by intact mucosa just as ranulas are, but they are solid rather than fluctuant and often bleed with minor trauma. Clearly, in addition to the strong suspicion based on the physical examination, a history of established or suspected HIV infection is crucial to correct inference. Complicating matters further, the incidence of ranula appears sharply increased in persons with HIV disease, according to one report from Zimbabwe.11
MANAGEMENT AND OUTCOME
This boy underwent a marsupialization procedure and was cured. Ten years postoperatively, as he approached adulthood, the ranula had not recurred. Not everyone does this well: a subset of patients require reoperation. New therapeutic procedures continue to be developed—most recently, carbon dioxide laser radiation,12 —while debate continues about marsupialization versus excision of the gland of origin.2,3
Schneiderman H, Nzeako UC. Ranula: regular and plunging varieties. CONSULTANT. 2005;45:1483-1489.
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