Many dermatologic conditions, inflammatory, immunologic, infectious, or neoplastic can also occur in the oral mucosa, with essentially similar clinicopathologic features. Occasionally, the mouth is the sole manifestation of a dermatologic condition as in the case with lichen planus, pemphigoid or erythema multiforme. There are also common conditions which are unique to the oral mucosa, such as recurrent aphthous stomatitis (canker sores) and geographic tongue. In this chapter, the reader will be introduced to the clinical characteristics, differential diagnosis, and management of common oral conditions.
ANATOMY OF THE ORAL CAVITY
The oral cavity consists of two parts, an outer vestibule, bounded by the lips and cheeks, and the oral cavity proper that includes the maxillary and mandibular alveoli and the gingiva, the hard and soft palate, floor of mouth, and tongue (Figure 33-1). The posterior aspect of the oral cavity proper is bounded by the faucial pillars and the tonsils. With the exception of the posterior one-third of the tongue, which is of endodermal origin, the epithelium that lines the oral mucosa derives from ectoderm. In contrast to the skin, the oral epithelium exhibits different patterns of keratinization. For example:
The masticatory mucosa (hard palate, gingiva, and alveolar mucosa) has keratinized (also referred to as orthokeratinized; no nuclei in the stratum corneum) or parakeratinized (retained nuclei in the stratum corneum) squamous epithelium.
The tongue has parakeratinized, non-keratinized, and specialized epithelia (papillae).
The buccal mucosa and vestibule have non-keratinized stratified or parakeratinized squamous epithelia, respectively.
The lips feature non-keratinized stratified squamous epithelium in their inner aspect, while the lip vermilion is orthokeratinized stratified with the intermediate area between the inner lip and the lip vermilion being surfaced by parakeratinizing stratified squamous epithelium.
Topographic landmarks of the oral mucosa. Reproduced with permission from Brunicardi FC, Andersen DK, Billiar TR, et al: Schwartz's Principles of Surgery, 11th ed. New York, NY: McGraw Hill; 2019.
The supporting connective tissue is of ectomesenchymal origin. Adnexal elements are not present in the connective tissue of the oral mucosa, with the exception of sebaceous glands, known as Fordyce granules/spots (Figure 33-2), which are present in 70–90% of individuals. However, the mouth has 800–1000 lobules of minor salivary glands, with the exception of the gingiva and the anterior aspect of the hard palate where salivary glands are not present.
Intraoral sebaceous glands (Fordyce granules). Small yellow papules on the vestibule and buccal mucosa.
CATEGORIES OF ORAL DISEASES
Clinically, oral lesions can be categorized as the following.
Ulcerated: Traumatic ulcers, recurrent aphthous stomatitis.
Vesiculobullous: Herpes simplex, herpes zoster, varicella, mucous membrane pemphigoid, pemphigus vulgaris, erythema multiforme, Stevens Johnson syndrome/toxic epidermolysis....