DefinitionLeukoplakia. A whitish, well-defined mucosalpatch or plaque caused by epidermalthickening or hyperkeratosis.• WHO. Leukoplakia is a white patch or plaquethat cannot be scraped off and cannot becharacterized as any other disease.
Age. The plaques are more frequent among oldermen.Site. Most often on the vermilion border of thelower lip, buccal mucosa, the hard and softpalates, and less frequent on the floor of themouth and other intraoral sites.They appear as localized, sometimes multifocal oreven diffuse, smooth or roughened, leathery,white, discrete areas of mucosal thickening.
MicroscopyVarious forms:1. hyperkeratosis without underlying epithelialdysplasia2. mild dysplasia3. severe dysplasia bordering on carcinoma in situ.Only histologic evaluation distinguishes these lesions.
Risk of malignancy• Malignant transformation-- 3-25% (depending somewhat onlocation• The transformation rate is greatest with lipand tongue lesions and lowest with those onthe floor of the mouth.• The more the dysplasia the greater theprobability of cancerous transformation.
Differential Diagnosis• Hairy leukoplakia- AIDS, corrugated surface,not related to oral cancer.• Verrucous leukoplakia- corrugated, recurs,spreads…diffuse warty type, harbor SCC.• Erythroplakia- red, velvety, often granular,circumscribed areas that may or may not beelevated, having poorly defined, irregularboundries. Marked epithelial dysplasia,malignant transformation is more than 50%.
Cancersof the oral cavity and tongue• The most common cancers of oralcavity are squamous cell carcinomas.These cancers tend to occur late inlife and rarely before the age of 40years..
Clinical features• Mostly asymptomatic so the lesion is ignored.• May cause local pain and difficulty inchewing.• As a result , a significant number are notdiscovered until beyond cure. About halfresult in death within 5 years and indeed mayhave already metastasized by the time theprimary lesion is discovered
Prognosis• 90. At an early stage 5 year survival canexceed 90%.• 40.The overall 5 year survival rates aftersurgery and adjuvant radiation andchemotherapy are about 40% for cancers ofthe base of the tongue, pharynx, and floor ofthe mouth without lymph node metastasis,• 20.with less than 20% for those with lymphnode metastasis.
Risk factors for oral cancerFactor1. Leukoplakia,erythroplakia2. Tobacco use3. HPV 16& 184. Alcohol abuse5. Protracted irritationComments• Risk of transformation in leukoplakia is 3% to 25%• More than 50% risk in Erythroplakia.Best established influence particularly pipe smoking and smokeless tobacco.30-50 of casesWeaker influence than tobacco use, but the two habits interact to greatly increaseriskWeakly associated
Morphology• Predominant sites:• 1. Vermilion border of the lateral margins of thelower lip,• 2. floor of the mouth, and• 3. lateral borders of the mobile tongue.
Morphology cont.• Early lesions appear as pearly white to gray,circumscribed thickenings of the mucosa closelyresembling leukoplakic patches. They then maygrow in an exophytic fashion to produce readilyvisible and palpable nodular and eventuallyfungating lesions, or they may assume anendophytic, invasive pattern with centralnecrosis to create a cancerous ulcer.
Morphology cont.• The squamous cell carcinomas are usuallymoderately to well differentiated keratinizingtumors.• Before the lesions become advanced it may bepossible to identify epithelial atypia, dysplasia, orcarcinoma in situ in the margins, suggesting originfrom leukoplakia or erythroplakia.
Morphology cont.• Spread to regional nodes is present at thetime of initial diagnosis only rarely with lipcancer, in about 50% of cases of tonguecancer, and in more than 80% of those withcancer of the floor of the mouth. Moreremote spread to tissue or organs is lesscommon than extensive regional spread.
Salivary gland tumors• About 80% of tumors occur within the parotidglands and most of the others in the submandibularglands.• Males and females are affected about equally,usually in the sixth or seventh decade of life.• In the parotids 70% to 80% of these tumors arebenign.
List of Salivary gland tumors• Benign tumors:• Pleomorphic adenoma• Warthin tumor• Malignant tumors:• Mucoepidermoid tumor
1. Pleomorphic adenoma. The dominant tumorarising in the parotids isthe benign pleomorphic adenoma, which issometimes called a mixed tumor of salivary glandorigin.2. Warthin tumor. Much less frequent is thepapillary cystadenoma lymphomatosum ( Warthintumor).Collectively these two types account for three-fourthof parotid tumors. These tumors present clinicallyas a mass causing swelling at the angle of jaw.
• The most malignant tumor of the salivary gland ismucoepidermoid carcinoma which occurs mainlyin parotids.• When primary or recurrent benign tumors arepresent for many years (10-20), malignanttransformation may occur, referred to then as amalignant mixed salivary gland tumor.• Malignancy is less common in the parotid gland(15%) than in the submandibular glands (40%).
• Despite the tumor’s encapsulation histologicalexamination often reveals multiple sites where thetumor penetrates the capsule.• Adequate margins of resections are thus necessaryto prevent recurrences. This may require sacrifice ofthe facial nerve, which courses through the parotidgland.• On average about 10% of excision are followed byrecurrences.
Pleomorphic Adenoma (Mixed Tumor of Salivary Glands).• This tumor accounts for more than 90% ofbenign tumors of the salivary glands.• It is a slow-growing, well-demarcated, apparentlyencapsulated lesion rarely exceeding 6 cm ingreatest dimension. Most often arising in thesuperficial parotid, it usually causes painlessswelling at the angle of the jaw and can be readilypalpated as a discrete mass. It is nonethelesspresent for years to before being brought tomedical attention.
Morphology• The characteristic histologic feature of PA isheterogenity. The tumor cells form ducts,acini, tubules, strands or sheets of cells. Theepithelial cells are small and dark and rangefrom cuboidal to spindle forms. Theseepithelial elements are intermingled with aloose, often myxoid connective tissue stromasometime containing islands apparentlycartilage or, rarely bone.
• Immunohistochemical evidence suggeststhat all of the diverse cell types withinpleomorphic adenoma, including those withinthe stroma, are of myoepithelial derivation.