Acute bacterial epiglottitis is a syndrome predominantly affecting young children who have an infection of the epiglottis caused by H. influenzae, in which pain and airway obstruction are the major findings. The onset is abrupt. Failure to appreciate the need to maintain an open airway for a child with this condition can have fatal consequences. The advent of vaccination against H. influenzae has greatly decreased the incidence of this disease.
Acute laryngitis can result from inhalation of irritants or may be caused by allergic reactions. It also may be caused by agents that produce the common cold and usually involve the pharynx and nasal passages as well as the larynx. Brief mention should be made of two uncommon but important forms of laryngitis: tuberculous and diphtheritic. The former is almost always a consequence of protracted active tuberculosis, during which infected sputum is coughed up. Diphtheritic laryngitis has fortunately become uncommon because of the widespread immunization of young children against diphtheria toxin. After it is inhaled, Corynebacterium diphtheriae implants on the mucosa of the upper airways, where it elaborates a powerful exotoxin that causes necrosis of the mucosal epithelium, accompanied by a dense fibrinopurulent exudate, to create the classic superficial, dirty-gray pseudomembrane of diphtheria. The major hazards of this infection are sloughing and aspiration of the pseudomembrane (causing obstruction of major airways) and absorption of bacterial exotoxins (producing myocarditis, peripheral neuropathy, or other tissue injury).
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In children, parainfluenza virus is the most common cause of laryngotracheobronchitis, more commonly known as croup, but other agents such as respiratory syncytial virus also may precipitate this condition. Although self-limited, croup may cause frightening inspiratory stridor and harsh, persistent cough. In occasional cases, the laryngeal inflammatory reaction may narrow the airway sufficiently to result in respiratory failure. Viral infections in the upper-respiratory tract predispose the patient to secondary bacterial infection, particularly by staphylococci, streptococci, and H. influenzae.
Nasopharyngeal carcinoma is a rare neoplasm that merits comment because of (1) the strong epidemiologic links to EBV and (2) the high frequency of this cancer among the Chinese, which raises the possibility of viral oncogenesis on a background of genetic susceptibility. It is thought that EBV infects the host by first replicating in the nasopharyngeal epithelium and then infecting nearby tonsillar B lymphocytes. In some individuals, this leads to transformation of the epithelial cells. Unlike the case with Burkitt lymphoma (Chapter 12), another EBV-associated tumor, the EBV genome is found in virtually all nasopharyngeal carcinomas, including those that occur outside the endemic areas in Asia.