Pathology of the oral cavity affects the following structures: (1) the mucosa, (2) the salivary glands, and (3) the jaw bones. Lesions may extend into the oropharynx, sinuses, and the skin. As such, the scope of practice of oral and maxillofacial pathology overlaps with head and neck pathology, dermatopathology, and orthopedic pathology. The oral cavity is also the primary site for the development of lymphomas and many soft tissue tumors, and is also sometimes the location of metastatic tumors. This atlas focuses on pathology that is frequently seen in the oral cavity.
Unlike the skin, mucosal lesions in the oral cavity may manifest only in a limited number of ways—erythematous, white (from keratosis or underlying fibrosis), yellow (from fibrinous exudate), papillary, diffuse or nodular swelling, mass, erosive or vesicobullous, and pigmented. It is important for the pathologist to be familiar with clinical presentations of mucosal disease because this affects the final diagnosis and is particularly important for keratotic lesions, leukoplakias, and mucosal disease.
The oral mucosa varies clinically and histologically from site to site, and can be divided into keratinized and nonkeratinized mucosa (Fig. 1-1). Knowledge of clinical aspects of oral disease must be correlated with oral anatomy: for example, recurrent aphthous ulcers occur primarily on the nonkeratinized mucosa, whereas recurrent herpes simplex infections occur almost exclusively on the keratinized mucosa in immune-competent patients. The tongue dorsum but not ventrum is specialized for gustatory, masticatory, and deglutition functions. Taste buds are present within fungiform (dorsum), circumvallate (8 to 14 on the posterior dorsum), and foliate (posterior lateral tongue) papillae but not within filiform papillae (Fig. 1-2). The oral mucosa contains no submucosa per se because there is no muscularis mucosa or any other clearly recognizable histologic landmark that separates mucosa from submucosa. As such, the terms papillary, superficial, and deep lamina propria are preferable to submucosa. In general, the epithelium of the oral cavity is much thicker than that of the skin (Table 1-1; Figs. 1-3 to 1-9). Muscle is present fairly superficially on the tongue and slightly deeper on the buccal and labial mucosa. Minor salivary glands are predominantly mucous, although serous acini and demilunes are frequently seen (Fig. 1-10); they are present everywhere in the mouth except on the attached gingiva and tongue dorsum. Serous salivary glands with a smaller mucous component are frequently encountered on the anterior ventral (glands of Blandin-Nuhn) and posterior lateral and dorsal (glands of von Ebner) tongue, often invested in muscle. Lingual tonsils are located on the posterior dorsum and posterior lateral tongue.