Potentially malignant disorders

Key Points

Potentially malignant (sometimes termed premalignant) clinically obvious disorders include actinic cheilitis, erythroplakia (erythroplasia – red patch), leukoplakia (white patch), submucous fibrosis and lichenoid lesions (Ch. 29)

Risk factors for erythoplakia and leukoplakia may include tobacco use, alcohol use, betel nut chewing and sunlight exposure

Diagnosis and prognosis are aided by biopsy

Factors predictive of future malignant transformation may include dysplasia, history of cancer in the upper aerodigestive tract, and changes in expression of P53 tumour suppressor protein, DNA and chromosomes 3p or 9p

Treatment involves removing risk factors, and excision of dysplastic lesions

INTRODUCTION

Most mouth cancers are oral squamous cell carcinomas (OSCC) and appear to arise in apparently normal mucosa, in apparently otherwise healthy people but some are preceded by clinically obvious potentially malignant (sometimes termed premalignant) disorders (PMD) and OSCC is also increased in patients who:

have had previous oral malignancy

have had previous malignancy in the upper aerodigestive tract (nose, pharynx, trachea, lungs, oesophagus)

are immune incompetent.

PMD include (Table 25.1) mainly:

Table 25.1

Potentially malignant oral disorders

Disorder		Aetiological factors	Features
Actinic cheilitis (solar elastosis)		Sunlight	White plaque/erosions
Erythroplasia		Tobacco/alcohol/betel	Flat red plaque
Leukoplakia	Homogeneous	Tobacco/alcohol/betel, human papilloma virus	White plaque
Leukoplakia	Speckled (erythroleukoplakia)	Tobacco/alcohol/betel, human papilloma virus	Speckled plaque
	Nodular/verrucous	Tobacco/alcohol/betel, human papilloma virus	Nodular white plaque
	Proliferative verrucous leukoplakia	Tobacco/alcohol	White or speckled nodular plaque
	Sublingual leukoplakia	Tobacco/alcohol	White plaque
	Candidal leukoplakia	Candida albicans	White or speckled plaque
	Syphilitic leukoplakia	Syphilis	White plaque
Lichen planus		Idiopathic	White plaque/erosions
Submucous fibrosis		Areca nut/betel	Immobile mucosa, white plaque
Palatal lesions in reverse smokers		Tobacco	White or speckled plaque
Immunocompromised patients		Papilloma viruses Candidosis	White or speckled plaques
Discoid lupus erythematosus		Idiopathic	White plaque/erosions
Dyskeratosis congenita		Genetic	White plaques
Epidermolysis bullosa		Genetic	Scarring
Fanconi anaemia		Genetic	White plaques Periodontal disease
Paterson–Kelly syndrome (sideropenic dysphagia; Plummer–Vinson syndrome)		Iron deficiency	Postcricoid web
Xeroderma pigmentosum		Genetic	White plaque/erosions

Actinic cheilitis (solar elastosis) (Ch. 26).

Erythroplakia (erythroplasia – red patch; Fig. 25.1) (Ch. 27): defined by the World Health Organization (WHO) as ‘any lesion of the oral mucosa that presents as bright red velvety plaques which cannot be characterized clinically or pathologically as any other recognizable condition’. This is rare but has a very high malignant potential and many cases are already a carcinoma on microscopic examination.

Fig. 25.1 Erythroplakia: usually a potentially malignant disorder, or carcinoma

Leukoplakia (white patch; Figs 25.2–25.6) (Ch. 28): defined by the WHO as ‘clinical white patches that cannot be wiped off the mucosa and cannot be classified clinically or microscopically as another specific disease entity (such as lichen planus)’. Leukoplakia is, thus, a clinical diagnosis only and can only be made by exclusion. A workshop coordinated by the WHO Collaborating Centre for Oral Cancer and Precancer agreed that the term leukoplakia should be used to recognize ‘white plaques of questionable risk having excluded (other) known diseases or disorders that carry no increased risk for cancer’.

Fig. 25.2 Speckled leukoplakia: often a potentially malignant lesion

Fig. 25.3 No dysplasia detectable from this biopsy and thus the lesion is presumed benign

Fig. 25.5 Dysplasia: severe, and suggestive of a potentially malignant disorder

Fig. 25.6 Leukoplakia in a person who for most of his adult life drank a bottle of vodka and smoked 20 cigarettes daily; he also incidentally developed myeloma

Lichen planus/lichenoid lesions (Ch. 29): in many geographic areas these are the most common PMDs.

Submucous fibrosis (Ch. 30).

Palatal lesions in reverse smokers.

Apart from the conditions noted above, rare conditions that predispose to OSCC include:

discoid lupus erythematosus (Ch. 57)

dyskeratosis congenita (Ch. 57)

epidermolysis bullosa (Ch. 57)

Fanconi anaemia (Ch. 56)

Paterson–Kelly syndrome (sideropenic dysphagia; Plummer–Vinson syndrome) (Ch. 56)

Xeroderma pigmentosum (Ch. 57).

There are also occasional associations of OSCC with:

diabetes, and the metabolic syndrome

scleroderma.

Erythroplakia has a very high malignant potential. Leukoplakia can have a malignant potential – particularly high in the following types (Table 25.2):

Table 25.2

Malignant potential in the most important oral potentially malignant disorders

	Malignant potential
	High (> 60%)	Medium (< 30%)	Low (< 10%)
Main entities	Erythroplakia	Leukoplakia (non-homogeneous) Candidal leukoplakia	Leukoplakia (homogeneous) Lichen planus/lichenoid lesions
Uncommon entities		Actinic cheilitis Submucous fibrosis	Discoid lupus erythematosus
Rare entities	Dyskeratosis congenita*	Fanconi anaemia*