8 Oral lesions: differential diagnosis and biopsy techniques
Many oral lesions are first noticed by the patient or clinician as changes in the colour, texture or disruption of the mucosal surface, or as a swelling or asymmetry of the orofacial structures. When involving or arising from the underlying bone, these lesions may produce a variety of radiological changes, including radiolucencies with or without opacities, evidence of expansion and bone loss in the form of erosion or resorption.
Securing the diagnosis is fundamental to safe and successful management of the patient and will depend on a clear and concise history, careful clinical examination and the use of additional special investigations including radiography, biopsy and other laboratory and diagnostic techniques. Within this spectrum, biopsy is a commonly performed test and is detailed later in this chapter. Should the lesion appear malignant, biopsy should not be performed in general practice, but the patient should be referred immediately for a specialist opinion (see Ch. 10). This approach avoids the need for the general practitioner to break unexpected/distressing news with the consequent requirement to explore the management options with a now anxious patient.
Soft-tissue oral lesions are common, often symptomless, slow-growing lumps and are first noticed by the clinician at a routine examination so the clinical history might not contribute greatly to making the diagnosis. Pain is unusual and would indicate infection in a lesion such as a cyst (secondary infection, see Ch. 9). On rare occasions it may indicate aggressive behaviour, e.g. malignant tumour of minor salivary gland (Ch. 14).
The posterior palate, lateral third of hard palate and upper lip are particularly high-risk sites for minor salivary gland tumours. The lower lip is a common site for mucoceles, whilst the buccal mucosa is a common site for fibroepithelial polyps particularly when associated with missing teeth.
Colour will distinguish between fibroepithelial polyps (pink) (Fig. 8.1) and the white rough cauliflower presentation of viral papillomas (warts) (Fig. 8.2). Mucous cysts tend to be translucent with a bluish colour (see Figs 14.7, 14.8) and haemangiomas and ‘venous lakes’ (Fig. 8.3) dark blue. Pyogenic granulomas (Fig. 8.4) and giant-cell epulides (Fig. 8.5) normally present as maroon/red.
Lesions may also be distinguished by their depth within the oral tissues and their relationship to adjacent structures. This will differentiate superficial lesions such as fibroepithelial polyps, viral papillomas and epulides (gingival swellings) from submucosal lesions. Palpation is essential to define the lesion’s consistency and distinguish between discrete and diffuse swellings, or whether the lesion is mobile or attached to deeper structures. Solid submucosal lesions can be reactive (e.g. lymph nodes) or neoplastic arising from any of the submucosal structures (e.g. adenomata of minor salivary glands and neurilemmomas). All submucosal swellings that are solid have the potential to be neoplastic and must be investigated.
The intraoral environment having given rise to lesions may in turn alter their morphology, depending on site. For example, fibroepithelial polyps can vary in presentation from ‘leaf fibromas’ in the palate to denture-induced hyperplasia at the periphery of a denture (see Figs 11.5, 11.6). Immature or developing polyps, particularly when arising from the gingivae, are described as pyogenic granulomas and the pregnancy epulis is a variant. They present as red, acutely inflamed lesions that are soft and bleed readily. Similar in presentation is the peripheral giant-cell granuloma although this may be more purple.
Almost all the lesions described so far present as single and discrete swellings. The presence of multiple lesions is of significance and indicates systemic disorders. Examples include the mucosal tags and polyps in oral Crohn’s disease/orofacial granulomatosis and multiple viral papillomas of HIV infection.
White and red patches are discussed in detail in Chapter 10 (see Figs 10.1, 10.2), but it should be noted that a wide array of white patches that have no significant malignant potential can occur. The difficulty is that interpretation of this risk almost always requires a histological diagnosis. Biopsy is therefore mandatory for all unexplained lesions and the decision not to biopsy requires clinical experience in the management of these types of lesions.
A variety of pigmented lesions may present within the oral cavity; they may be blue, brown or black in colour, flat (macule), raised or granular (papule) and single or multiple. Common single macular lesions include amalgam tattoos and benign naevi. Multiple macular lesions include racial deposits and lesions secondary to chronic inflammatory damage to the epithelium such as lichen planus and tobacco-induced melanosis. However, in common with white/red lesions, biopsy may be indicated to confirm the diagnosis. It is essential that, as with leukoplakia, any recent history of ulceration, haemorrhage or change in the type (becomes papular) or size of a lesion is to be regarded as serious when urgent referral is mandatory.
Where the diagnosis is clinically evident as in the case of fibroepithelial polyps, viral papillomas or mucous cysts, biopsy is not required for diagnosis although where treatment involves excision, the specimen should always be submitted for histological confirmation. If there is doubt or the lesion is arising deep to the mucosa then histological diagnosis is essential.
The primary management objective is to establish the diagnosis. This may require nothing other than clinical examination as for a squamous papilloma or mucous cyst, but often and particularly for solid/firm submucosal lesions does require biopsy. Subsequent treatment will depend not only on the clinical significance of the diagnosis but on the presence of related symptoms and the site and size of the lesion.
Lesions causing problems, or which can be anticipated to do so, will require surgery or referral. Small, innocent lesions can be left, assuming they are not causing symptoms, increasing in size or of concern to the patient in terms of function or appearance.
In general, the size and site of the lesion do not change the technique but do require careful assessment of the patient and the level of experience of the operator. Larger lesions (greater than 2 cm), particularly submucosal ones, are more difficult to manage surgically. This is due to the access required and the risks to adjacent blood vessels and nerves. In addition they will be more difficult to repair and consequently they should not be attempted unless the operator is skilled in soft-tissue surgery and in dealing with the intraoperative and postoperative complications.
Surgical excision is the most common treatment for small lesions (fibroepithelial polyps, squamous papillomas and epulides) and is often completed as part of the biopsy (see below). It must, however, be combined with appropriate management of precipitating or causative factors. These include the elimination of chronic trauma for polyps or the removal of localized deposits of calculus for pyogenic granulomas. Peripheral giant-cell lesions will require a similar approach including curettage of the underlying bone. Epulides related to pregnancy are, unless they are large and causing distress, best left alone and removed if they persist postpartum, usually with an appropriate adjunctive periodontal therapy. Scaling and improved oral hygiene during pregnancy may reduce further growth and lessen the likelihood of surgery.
Surgical management of denture-induced hyperplasia must be combined with appropriate modification to the prosthesis such as temporary relining (Ch. 11). This is essential to retain sulcus form and prevent recurrence and is similarly so for ‘leaf-fibroma’ in the palate. Denture-induced hyperplasia can be extensive and, when affecting the lower jaw, is often related to other significant anatomical structures. This is particularly so in the anterior region where the main trunk of the mental nerve can be superficial due to resorption of the alveolus. The lingual nerve can also be at risk when the lingual side is operated on. In these circumstances it is important to carefully identify the edge of the hyperplastic tissue, to keep the excision superficial and to use blunt dissection to free the tissue from underlying structures (see section on biopsy).
Mucous cysts divide between the common extravasation cyst and the rarer retention cyst and present as tense bluish swellings often in the lower lip (see Fig. 14.7). These conditions are discussed in Chapter 14.
Vascular lesions are best considered as two groups: the rare haemangiomas, which can be extensive and multiple, and the common smaller degenerative malformations (varicosities) often seen on the lip in older patients (Fig. 8.3). For the former it is essential that the type, site and extent are fully evaluated, which normally requires referral to a specialist centre. For extensive and deep lesions or where there is any possibility that the haemangioma extends into bone, extractions or other surgery must be avoided until the type and extent of the vascular abnormality have been established. Conversely, discrete small lesions are easily dealt with either by excision with appropriate management of the vascular source or by cryotherapy. Indications for surgery are cosmetic or lesions that are repeatedly traumatized and bleed.
All submucosal solid lesions require investigation as the probability of them being neoplastic is high. Treatment selection is very much a balance between incisional biopsy to determine the histological diagnosis first and removal of the lesion in its entirety to avoid compromise of the site in terms of further surgery by potential seeding of tumour cells (e.g. pleomorphic salivary adenoma). This is often decided by the site and size of the lesion along with the results of specialist imaging such as CT or MRI scanning. For small lesions the careful combination of sharp and blunt dissection as described below should only be undertaken by clinicians skilled in soft-tissue surgery. As stated below, the excision of lesions arising under mucoperiosteum such as the palate requires the defect to be closed either by dressing the site and allowing repair by secondary intention or by primary repair with a mucosal flap or graft. Surgery in the soft palate area can be difficult, particularly if the lesion is deep where there is a possibility of perforation through to the nasal side.
Hard-tissue lesions can arise from odontogenic tissue or from bone. They present a range of diagnoses from developmental lesions such as palatal or mandibular tori or odontomas (see Figs 8.6, 11.13, 11.14) and bony exostoses, to the rarer benign and locally invasive lesions such as ossifying fibroma, ameloblastoma and cementoblastoma.
This is a complex group of lesions and conditions. Readers are referred to relevant pathology and radiology texts for more detailed descriptions of the various types and their histological and radiological findings. From the clinical standpoint they can be considered according to presentation: the common single discrete lesions (odontomes, odontogenic tumours and osteomata); the rare, large and diffuse lesions (fibrous dysplasia and Paget’s disease); and rare conditions with multiple lesions (Gardner’s syndrome and cemento-ossifying lesions).
Often they first come to attention as a bone-hard swelling beneath the overlying mucosa, but in many cases presentation is an incidental finding on routine radiography. As the symptoms and signs have so much overlap, diagnosis is largely dependent on radiological findings and, more importantly, histology. As described below, site can be an important sign in establishing the diagnosis: not only are the lesions within this group difficult to separate, they are often clinically and radiographically similar to cysts (see Ch. 9). As with soft-tissue lesions, there will be malignant counterparts, e.g. osteosarc/>