Pathology of the Head and Neck

Oral Cavity Chapter 3 97ynx. It is important to consider the site of involvementas the epidemiological factors can vary considerably intumours in different intraoral locations. There is typicallya higher frequency in men than women, and thisis attributed to the use of tobacco and alcohol [17]. Ithas been estimated that as many as 75% of cases of oralsquamous cell carcinomas in Western countries and Japancan be ascribed to these factors. Globally, oral canceraccounts for 5% of all malignancies in men and 2%in women [134]. Much higher rates, however, are seen inboth men and women in parts of southeast Asia, wherethey are usually associated with the habitual use of arecanut and tobacco products.3.8.2 Clinical FeaturesDespite the fact that oral tumours frequently causesymptoms, and the mouth can be readily visualisedwith simple equipment, many oral cancers present at arelatively advanced stage where treatment may be disfiguringand prognosis is poor. This is often becausemany patients are elderly and frail and frequently weardental prostheses and are accustomed to minor degreesof oral discomfort. In addition, early lesions may not beregarded as suspicious by the patient or the clinician andmay therefore be treated empirically with antibacterialor antifungal preparations.Any part of the oral mucosa can be the site of developmentof squamous cell carcinomas. The commonoral locations can show wide variations in different geographicalareas depending on the prevalent risk factors.The intraoral subsites include the buccal mucosa,tongue, floor of mouth, upper and lower gingivae andalveolar processes, the hard palate and retromolar trigone.As the clinical presentation can vary according tothe specific sites of involvement, these will be discussedseparately.3.8.2.1 Buccal MucosaThe buccal mucosa extends from the commissureanteriorly to the retromolar trigone posteriorly andfrom the upper and lower vestibular reflections. Themajority of carcinomas arise from the posterior areawhere they are commonly traumatised by the molarteeth. They soon spread into the underlying buccinatormuscle and though insidious initially they may eventuallycause trismus. Bone, however, is generally involvedonly in advanced tumours. Tumours at this site oftenextend posteriorly into the palatoglossal fold and tonsillarfossa. Metastases are most common in the submandibular,submental, parotid and lateral pharyngeallymph nodes.3.8.2.2 TongueThe tongue is the most common oral location of squamouscell carcinoma and can account for half of allcases. The majority affect the middle third of the lateralborder and adjacent ventral surface. The dorsum is avery uncommon site and tumours arising there may beassociated with precursor lesions such as lichen planusand candidal leukoplakia. Lingual tumours are oftenexophytic and ulceration is common. Even clinicallysmall tumours can infiltrate deeply into the underlyingmuscle. With progressive growth tumours becomeindurated and frequently develop characteristic rolled,raised, everted margins. Infiltration of the lingual musculaturemay cause pain, dysphagia and dysphonia.Half of patients have regional lymph node metastasesat presentation. Tumours towards the tip of the tonguedrain to the submental and thence to the jugulo-digastriclymph node, and those located on the dorsum andlateral borders tend to involve the submandibular andjugulo-digastric nodes. Contralateral or bilateral spreadis relatively common, particularly in tumours arisinganteriorly.3.8.2.3 Floor of MouthThe floor of the mouth is a horseshoe-shaped mucosaltrough extending between the lower lingual alveolarmucosa and the ventral lingual mucosa. It isthe second most common site for intraoral squamouscell carcinomas and shows the highest frequency ofsmall and symptomless tumours [115]. Tumours aremost frequent in the anterior segment and tumoursthere tend to spread superficially rather than deeply.Involvement of the submandibular duct can causeobstructive sialadenitis and tumours can also extenddown the duct itself. If the tumour extends to involvethe mandible, there can be spread along the periodontalligament and subperiostally [106]. Lymphatic involvementis early but less frequent than tumours ofthe tongue itself.3.8.2.4 Gingivaand Alveolar RidgeTumours at this site can be exophytic resembling dentalabscesses or epulides, or ulcerated and fixed to theunderlying bone. They account for about 20% of oraltumours. In parts of the USA there is a very high frequencyin women who practise snuff dipping. Relatedteeth are often loosened and there is extension along theperiodontal ligament. On the alveolus tumours can re-