Oral Health Group

Lumps and Bumps

A Practical Guide to the Differential Diagnosis of Submucosal Lesions

Diagnosis involves gathering data from the patientís history, clinical examination, and testing; interpreting the data that is obtained; then, formulating a differential diagnosis7.

Having an appropriate differential diagnosis will help to guide proper referral and treatment.
This article will give a framework to create a differential diagnosis for masses below the surface of the mucosa. Cutting into the wrong lesion could result in a significant bleed, a higher relapse rate, or ruining the margins of a malignant tumour prior to definitive treatment.

When faced with a lesion in the mouth, the most common reaction is to focus on it to the exclusion of all else. This can cause significant findings to be missed unless a systematic approach is taken.

Start first with an extra-oral examination, palpating for any lesions or lymphadenopathy in the neck, submandibular, and submental regions. Then, be sure to examine all the soft tissues of the mouth including the lips, buccal mucosa, gingiva, floor of mouth, tongue, hard/soft palate, and oropharynx.

After a lesion has been identified, it is important to describe as many attributes as possible including specific location, size, consistency, colour, surface alterations and ulcerations.

If the lesion has been monitored over subsequent appointments, note the changes that occur in the lesion between appointments. If photographs of the lesion are taken, they should be obtained before any surgical treatment has commenced. Remember that photographs form part of the patient’s record, and should be treated as such. If other testing is required (e.g. CT scan, MRI), it should ideally be obtained before biopsy or treatment.

Surgical biopsy is the last step in the diagnostic process, and should only be undertaken once a thorough history, examination, and testing, have all been completed.

Often times, the history of a lesion will immediately focus the differential diagnosis, and give a clue as to whether a lesion is benign or malignant. A dentist may not find much information when a patient relates that ‘I have a bump on my lip’, but may immediately suspect a mucocele when she says ‘This bump on my lip keeps going up and down, and I remember biting it about a year ago.’1

The duration of the lesion is important, because it can provide a clue as to its natural history. Mucoceles and infections can arise quite rapidly (days to weeks), but can also resolve just as quickly. On the other hand, benign tumours may be extremely slow growing, and be present for years. A rule of thumb is that a lesion that has been present for two weeks is infectious, two months malignant and two years benign, but there are always exceptions.

Any change in the lesion over time is also noteworthy. A mucocele may noticeably increase and decrease in size with time. Neoplasms (whether benign or malignant) rarely shrink.

Just because a growth is slow growing, however, does not mean it is benign. Some malignancies exist that are also slow-growing9 and may exist undetected by the patient such as polymophous low-grade adenocarcinoma and adenocystic carcinoma.11

This stresses the importance of biopsy and evaluation of any lesion, regardless of duration.5

Aside from questions regarding the natural history of the lesion, any symptoms the patient can report may also be useful. Malaise, fever, night sweats, and weight loss are all important clues that may assist in the patient’s diagnosis. A patient presenting with those symptoms, and a swelling in the neck (cervical lymphadenopathy) with lymph nodes greater than 1cm, may raise suspicion of lymphoma in an elderly patient, or leukemia in a young one1,2,8.

Keys: When asking about the lesion, inquire about any surface alterations & ulceration, pain, swelling, change in size/shape/location, duration, other symptoms (fever, night sweats, weight loss).

The frequency of lesions in the mouth varies with location. It is important to know which are common to an area as well as the severity of those lesions.

Fibromas* and mucoceles, which are benign reactions to irritation and trauma, will commonly occur on the lips and buccal mucosa. They are easy to excise and infrequently recur, although incomplete removal of an associated minor salivary gland can cause a mucocele to relapse. Submucosal lesions that look like a mucocele anywhere other than on an area prone to trauma should be viewed with caution as there is a greater chance of it being a minor salivary gland tumor. For instance, canalicular adenoma, a salivary gland neoplasm, may occasionally be encountered in submucosal lesions of the upper lip.12

Aside from a parulis related to a non-vital tooth, lesions on the gingiva are likely to be of a reactive nature.

Examples include pyogenic granuloma and peripheral ossifying fibroma, both of which are caused by a local irritant e.g., calculus. While the lesions may be easily removed, there is a high chance of recurrence unless the irritant is removed as well; it may be useful to curette adjacent teeth to removal all traces of foreign bodies6,13.

Another example of a reactive lesion which may occur on the gingiva is the peripheral giant cell granuloma3. As the name suggests, this lesion is composed of giant cells, and again, is reactive in nature. Removal of the lesion and the underlying irritant is usually curative. A common finding on the unattached gingiva or in the buccal vestibule is a fibrous epulis caused by a denture. These are usually leaf-like or ridge-like lesions that are caused by ill-fitting denture flanges that create pressure and trauma on the mucosa. Severe cases may produce multiple ridges that are unhygienic and can become infected. Treatment involves denture modification and surgical removal of the epulis.

Lesions of the tongue may occur in different frequencies, depending on the specific location of the tongue examined.
The tongue can be divided into three zones; the anterior dorsal (top front), posterior dorsal (top back) and ventral (underside). Fibromas are common in all three. Benign nerve sheath tumors (schwannoma, neuroma and granular cell tumors) occur; the same lesions occur more frequently in the anterior dorsum of the tongue. The ventral surface of the tongue will commonly exhibit varicose veins (varix), especially in the elderly. They typically have a deep blue hue, and will blanch with pressure.

Inflammatory papillary hyperplasia is a common lesion that can occur on the hard palate, typically beneath an unhygienic denture that is worn 24 hours a day. The lesion may resolve by itself after leaving the denture out; or, a combination of new denture, antifungal agents, and surgical therapy may be required. Regardless of the treatment modality, patient instruction and education is important to prevent recurrence. Other submucosal lesions that may occur on the hard palate include abscess related to a necrotic tooth, minor salivary gland tumours (discussed below), as well as mesenchymal tumours such as the neurofibroma.

Pathology on the soft palate deserves special attention, as subepithelial lesions in this area have a higher than average chance of either recurring or being malignant.

As a general rule, any firm, submucosal mass on the soft palate should be considered malignant until proven otherwise. Care during biopsy is required to prevent distorting lesion margins, or to minimize the risk of recurrence. Pleomorphic adenoma is the most common benign salivary gland tumour that occurs on the palate, and has tentacle-like extensions away from the main tumour mass. There is a significant risk of recurrence unless excision is completed with wide margins to include these extensions4. Human papilloma virus (HPV)-related and denture-epulis lesions are also common on the palate. Treatment is
surgical excision, although papillomas should be re-evaluated after removal as they have a high recurrence rate.

As stated above, the first key to forming a differential diagnosis and developing a treatment plan for any pathologic lesion is obtaining a thorough history and performing a comprehensive examination. The information obtained will provide important clues to the diagnosis of the lesion, help to guide additional testing and appropriate treatment.

When faced with an unknown lump or bump, remember these rules of thumb:

• Any submucosal lesion in the roof of the mouth should be considered a malignancy until proven otherwise. The borders of those lesions should not be disrupted in case further surgery is necessary.

• If a lesion is going to be completely removed because it is small in size, make sure to carefully note the location.

• Be wary of any lesion that is hard and fixed. Minor salivary gland tumors typically present this way and can be slow growing.

• Be aware that distant metastases can present as submucosal nodules in the mouth e.g., renal metastasis to the tongue.

A short list of lesions to consider in a differential diagnosis includes:

Gingiva: fibroma, pyogenic gran­u­loma, peripheral ossifying fibroma;

Lip: fibroma, mucocele, salivary gland tumour;

Anterior Dorsal: fibroma vs. nerve sheath tumor;

Anterior Vental: fibroma vs. varix;

Posterior Doral: fibroma vs. lingual tonsil;

Cheek: fibroma, mucocele, epulis;

Palate: fibroma, papilloma virus related lesion, salivary tumours, higher risk of malignancy;

Neck: infectiously mphadenopathy vs. malignant lymphadenopathy.

By carefully reviewing the history of a lesion and knowing the most frequent lesion in each location of the mouth the primary care provider can dramatically increase the odds of correctly diagnosing submucosal lesions.OH

Ian M. Furst DDS, MSc, FRCD(C), FICD*, Stephen Cho DDS, FRCD(C)*, Angela Waciuk DDS, MSc, FRCD(C)**

Oral & Maxillofacial Sur­gery* & Periodontology**, Cam­bridge Memorial Hospital and Cor­on­ation Dental Specialty Group, Cam­bridge, Ontario, Canada.

The authors wish to thank Dr. Tom Daley of the London Health Sciences Centre.

Oral Health welcomes this original article.

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