Chapter 11 Head and Neck
Head and neck is the colloquial term used for the face and underlying structures of the upper respiratory and alimentary tracts, the ears, and the neck organs. The diseases of this area are usually treated by dentists and oral surgeons and otorhinolaryngologists (ear, nose, and throat specialists).
Caries is a dental disease characterized by decay of enamel and dentin caused by bacteria. The most important pathogen is the acid-producing Streptococcus mutans, which thrives in saliva that contains residual sugar from the food. The attachment of bacteria to teeth is promoted by the formation of plaques (i.e., masses of calcified debris and desquamated epithelium that are seen on the surface of enamel).
Figure 11-1 Caries and periodontal diseases. Caries begins as a bacterial plaque (A), which leads to a defect in enamel (B). Deeper defects allow the entry of bacteria into the pulp cavity (C). Pulpitis is a bacterial infection that may extend into the root canal (D). Periodontal disease is caused by bacteria that colonize the gingival pockets (E). Extension of infection into the periapical bone leads to the formation of periapical granuloma (F).
(From Damjanov I: Pathology for the Health-Related Professions, 3rd ed. Philadelphia, Saunders, 2006, p. 230.)
Periodontitis is the inflammation of the periodontal recesses, involving the gingiva, periodontal membrane, and alveolar bone of the tooth socket. It may be associated with gingivitis, pyorrhea (pus oozing from the tooth socket), resorption of the peridental bone, and loosening and loss of teeth. Periodontal disease is the most common cause of tooth loss in the United States.
Exudative pharyngitis with swollen lymph nodes, hairy leukoplakia in acquired immune deficiency disease
HSV-1 infection often involves the mouth. Most often, it causes clusters of small vesicles on the lips (herpes labialis), but it may also cause widespread gingivostomatitis. Blisters tend to rupture and transform into ulcers, which form a crust and heal spontaneously.
Following the initial HSV-1 infection, the virus migrates along the facial nerves into the trigeminal ganglion, where it may remain in a dormant form indefinitely. Various other infections and even stressful conditions may activate the virus in the trigeminal ganglion. Activated viruses migrate along the nerves into the labial mucosa or skin, and thus herpetic vesicles reappear. Most often, reactivation of HSV-1 occurs after the common cold, which is why the herpetic vesicles are often called cold sores or fever blisters.
Herpangina is an acute vesicoulcerative mucosal infection caused by Coxsackie A virus. It tends to occur in epidemics and affects small children. It begins in the form of vesiculopapular red lesions on the tonsils, soft palate, and uvula. These lesions are painful and ulcerate but heal spontaneously over a period of 2 to 5 days.
Aphthae are shallow ulcers that occur on the oral mucosa. The cause of these lesions is not known, but in some people they tend to recur months or years after the initial occurrence. Minor aphthae (<5 mm) last a few days and heal without scarring. Major aphthae (>1 cm) may persist for longer periods and may evoke scarring. Aphthae tend to involve movable parts of the mouth (inner surface of the lips and buccal mucosa or the tongue), in contrast to herpetic infections, which also affect the gingivae.
Exudative pharyngitis and tonsillitis caused by Streptococcus pyogenes are colloquially called strep throat. Infection with group A β-hemolytic S. pyogenes accounts for less than one third of all conditions suspected clinically to be strep throat. The most common causes of exudative pharyngitis are viruses, which account for more than 50% of all such infections.
Infection with S. pyogenes is accompanied by fever, swelling of the neck, and pain on swallowing. The pharynx appears beefy red and moist, and a fibrinous grayish-yellow exudate appears on the tonsils. The cervical and submaxillary lymph nodes may become enlarged and painful. Definitive diagnosis depends on demonstrating streptococci in throat swab cultures. Antibodies to streptolysin O appear in the blood of 80% of reconvalescents after 2 weeks or later. It is important to follow the rise of the titer of these antibodies because they may be high from a previous infection.
Thrush is the common name for oral infection caused by Candida albicans. It presents in the form of white pseudo-membranes covering the mucosal surface of the tongue, buccal mucosa, or anywhere else in the oropharynx. These mucosal plaques can be easily scraped away, revealing an inflamed oral mucosa.
C. albicans is a common fungal saprophyte, found in approximately 40% of all healthy adults. Overgrowth of fungi is encountered in people suffering from diabetes, debilitating diseases, and immunodeficiency states and in cancer patients treated with cytotoxic drugs. Oral candidiasis is also encountered in some bottle-fed infants and older children treated with broad-spectrum antibiotics.