Herpes Simplex Stomatitis
Herpes simplex type 1 is a common viral infection of the oral mucosa. The primary infection occurs in children or young adults as a widespread gingivostomatitis, characterized by multiple vesicles that rupture early to form ulcers. Systemic symptoms such as fever are present. Although locally severe, the disease is self-limited, and recovery is the rule.
Herpes simplex virus passes up the nerve trunks and infects the ganglia during the acute phase, where it remains dormant for long periods. Reactivation of the infection occurs repeatedly in some patients, with the virus passing down the nerve to the oral mucosa to form isolated vesicular lesions and ulcers (herpes labialis—fever blisters and cold sores). Reactivation is often precipitated by a concurrent fever or common cold or by exposure to sunlight. About 20% of the population is affected.
Candidiasis (Oral Thrush)
Candida albicans is a normal commensal of the mouth. Clinical infection of the oral mucosa usually represents an opportunistic infection in a patient with increased susceptibility. Persons at risk are those with immunosuppression, eg, acquired immune deficiency syndrome (AIDS) patients or those receiving cancer chemotherapy; newborn infants; patients with diabetes; and sick patients who receive long-term antibiotic therapy.
Candida produces inflammation and edema of the epithelium, forming white patches that leave raw ulcerated lesions when they are rubbed off. The budding yeasts and pseudohyphae of Candida can be identified in smears, cultures, or biopsy specimens from the lesion.
Aphthous stomatitis is a common disorder characterized by recurrent episodes of painful shallow ulcers (canker sores) on the oral mucosa. The pathologic picture is of nonspecific acute inflammation. The cause is unknown—psychosomatic and allergic mechanisms have been suggested; no infectious agent has been identified. The disease is usually self-limited. Rarely, it is associated with genital and conjunctival ulcers and neurologic abnormalities (Behçet's syndrome).
Rare Infections of the Oral Cavity
Actinomyces israelii and Actinomyces bovis cause chronic suppurative inflammation in the mouth and jaw. Patients present with an indurated jaw mass that has multiple sinuses opening to the skin surface, which drain pus. The pus typically contains visible small colonies of the organism (sulfur granules). Actinomyces species are gram-positive filamentous bacteria that are part of the normal mouth flora, and actinomycosis usually follows dental extraction. The organism is sensitive to penicillin.
A wide variety of spirochetes and fusiform bacilli inhabit the mouth. In debilitated or malnourished individuals, they may cause severe ulcerative gingivitis (Vincent's angina, or trench mouth).
Syphilis may involve the mouth in all three stages. In primary syphilis, the chancre may be on the lips or tongue; in secondary syphilis, superficial mucous patches and snail track ulcers may be present; in tertiary syphilis, chronic inflammation may produce tongue ulcers or large granulomas (gummas). Congenital syphilis also produces scarring at the angles of the mouth (rhagades). Abnormalities in the permanent teeth—Hutchinson's incisors and Moon's ulcers—are described in Chapter 54: Sexually Transmitted Infections.
Skin Diseases Manifesting in the Mouth
The following skin diseases are frequently manifested in the mouth, with or without concurrent skin lesions: (1) lichen planus, (2) pemphigus vulgaris, (3) bullous pemphigoid, and (4) erythema multiforme (Stevens-Johnson syndrome). The histologic features of these lesions are characteristic and permit diagnosis (Chapter 61: Diseases of the Skin).
Benign “Tumors” of the Oral Cavity
A large number of lesions present clinically as a mass in the oral cavity. Not all are neoplasms.
Mucocele (Mucus Escape Reaction)
Mucoceles represent a localized inflammatory reaction to the escape of mucus from a ruptured minor salivary gland or duct. They are usually small white cystic structures. More rarely, they become large and stretch the overlying mucosa. Large mucoceles of the floor of the mouth resulting from damage to the submandibular or sublingual salivary ducts are called ranulas.
Pyogenic granuloma is a common oral lesion that is the result of a reactive inflammatory proliferation of granulation tissue. It presents as a small, bright red nodule with ulceration of the overlying mucosa (Figure 31-2). Pyogenic granulomas occur commonly during pregnancy (pregnancy tumor). The cause is unknown. They resolve spontaneously.
Pyogenic granuloma of upper gingiva. This appeared as a fleshy red mass projecting between two teeth (arrow).
The term epulis signifies a local reactive inflammatory lesion of the gum that presents as a mass. It includes pyogenic granuloma as well as a distinct lesion composed of multinucleated giant cells (giant cell epulis). A form of congenital epulis is characterized by the proliferation of large cells with abundant granular cytoplasm (granular cell epulis).
Thyroid tissue at the root of the tongue is a rare condition that represents incomplete descent of thyroid tissue in the embryo. It usually coexists with a normal thyroid but in rare cases represents the individual's only thyroid tissue.
Benign Neoplasms of the Oral Cavity
Benign neoplasms in the oral cavity may arise from the squamous epithelium (squamous papilloma), from mesenchymal cells (fibroma, lipoma, neurofibroma), or from minor salivary glands (adenomas). One benign tumor that occurs commonly in the tongue is the granular cell tumor, probably a variant of a schwannoma in which the cells have abundant granular cytoplasm.
Squamous Carcinoma of the Oral Cavity
Squamous carcinoma accounts for over 95% of malignant neoplasms in the oral cavity and 5% of all cancers in the United States. Cancers arising in the lower lip (40%), the tongue (20%), and the floor of the mouth (15%) account for the majority. Involvement of the upper lip, palate, gingiva, and tonsillar area (5% each) is less common. The mucosa of the cheek is rarely the primary site for squamous carcinoma.
Oral cancer is much more common in men than in women. In the United States, oral cancer is most strongly related to tobacco chewing, particularly in baseball players. Cigarette and pipe smoking and alcohol are also associated.
Oral cancer is extremely common in Sri Lanka and parts of India, where chewing betel is common—betel is a green leaf that is mixed with areca nut, limestone, and tobacco to form a cud. The carcinogenic agent is believed to be in either the limestone or the tobacco. In parts of Italy where it is customary to smoke cigars with the lighted end inside the mouth, polycyclic hydrocarbons are believed to be the agents responsible for causing squamous carcinoma.
Squamous cancer begins as a painless indurated plaque on the tongue or oral mucosa that commonly ulcerates to form a malignant ulcer. The lesion is usually readily visible, and diagnosis is made by biopsy. A significant number of patients with oral cancer present first with involved cervical lymph nodes. In very advanced local disease, there may be fixation of the tongue, interfering with speech and swallowing.
The earliest lesion is squamous epithelial dysplasia, the most severe form of which is carcinoma in situ. At this stage there may or may not be visible whitish thickening (leukoplakia) of the epithelium (see below); however, most lesions are invasive to a variable depth at the time of diagnosis. The degree of differentiation varies; most tumors are well differentiated.
Oral cancer spreads primarily by lymphatics. Cervical lymph nodes are involved early. Bloodstream metastasis occurs late.
Leukoplakia is a term applied to visible flat, white lesions of the oral or genital mucous membranes. In most instances, it is due simply to hyperkeratosis (increased thickness of keratin layer) resulting from chronic irritation. In some instances, however, epithelial dysplasia is present, and the lesion is then considered precancerous. Persistent leukoplakia should therefore be biopsied.
Treatment of oral squamous carcinoma is by radical surgery, radiotherapy, and chemotherapy. Squamous carcinoma of the oral cavity is sensitive to radiation therapy. The prognosis depends on the stage of the disease and is relatively good in the absence of cervical lymph node involvement.
Other Malignant Neoplasms of the Oral Cavity
Rare malignant neoplasms in the oral cavity include malignant lymphomas and carcinomas of minor salivary gland origin. Malignant melanoma is very rare.