Porth's Essentials of Pathophysiology, 4e

1159

Disorders of Skin Integrity and Function

C h a p t e r 4 6

and famciclovir may be used for prophylaxis. Sunscreen applied to the lips can prevent sun-induced herpes sim- plex. Efforts to develop vaccines to prevent HSV infec- tions are in process. 13 Herpes Zoster. Herpes zoster (shingles) is an acute, localized vesicular eruption distributed over a derma- tomal segment of the skin. 14 It is caused by the same herpesvirus, varicella-zoster, that causes chickenpox. It is believed to be the result of reactivation of a latent varicella-zoster virus infection that was dormant in the sensory dorsal root ganglia since a primary childhood infection. During an episode of herpes zoster, the reac- tivated virus travels from the ganglia to the skin of the corresponding dermatome (Fig. 46-10A). Although her- pes zoster is not as contagious as chickenpox, the reacti- vated virus can be transmitted to nonimmune contacts. The incidence of herpes zoster increases with age; it occurs most frequently in persons older than 60 years of age. The normal age-related decrease in cell-mediated immunity is thought to account for the increased viral activation in this age group. Other persons at increased risk because of impaired cell-mediated immunity are persons with conditions such as HIV infection and certain malignancies, and those receiving long-term corticosteroid treatment, cancer chemotherapy, and radiation therapy. The lesions of herpes zoster typically are preceded by a prodrome consisting of a burning pain, a tingling sen- sation, extreme sensitivity of the skin to touch, and pru- ritus along the affected dermatome (see Chapter 35). Among the dermatomes, the most frequently involved are the thoracic, the cervical, the trigeminal, and the lumbosacral. 14 Prodromal symptoms may be present for 1 to 3 days or longer before the appearance of the rash. During this time, the pain may be mistaken for a number of other conditions, such as heart disease, pleurisy, musculoskeletal disorders, or gastrointestinal disorders. The lesions appear as an eruption of vesicles with ery- thematous bases that are restricted to skin areas supplied by sensory neurons of a single or associated group of dorsal root ganglia (Fig. 46-10B). In immunosuppressed persons, the lesions may extend beyond the dermatome. Eruptions usually are unilateral in the thoracic region, trunk, or face. New crops of vesicles erupt for 3 to 5 days along the nerve pathway. The vesicles dry, form crusts, and eventually fall off. The lesions usually clear in 2 to 3 weeks, although they can persist up to 6 weeks in some elderly persons. Serious complications can accompany eruptions. Eye involvement can result in permanent blindness and occurs in a large percentage of cases involving the oph- thalmic division of the trigeminal nerve (see Chapter 38). Postherpetic neuralgia, which is sharp, burning pain that persists longer than 1 to 3 months after the resolution of the rash, is seen most commonly in persons older than 60 years of age (see Chapter 35). The treatment of choice for herpes zoster is the admin- istration of an antiviral agent (e.g., acyclovir, valacy- clovir, famciclovir). 14 Treatment is most effective when

started within 72 hours of rash development. When given in the acute vesicular stage, the antiviral drugs have been shown to decrease the amount of lesion devel- opment and pain. Narcotic analgesics, tricyclic antide- pressants, gabapentin, anticonvulsant drugs, and nerve blocks have been used for management of postherpetic neuralgia. Local application of capsaicin cream or lido- caine patches may be used in selected cases. Palliative treatments, such as heat and gentle pressure, may also be helpful. A live herpes zoster vaccine is available to prevent both herpes zoster and postherpetic neuralgia. The vac- cine is recommended for use in people 60 years of age and older, although the efficacy of the vaccine continues to be studied. 15,16 Pustular Disorders Although acne vulgaris, acne conglobata, and rosacea may present with a variety of skin lesions, they are char- acterized by the presence of pustules, which are circum- scribed skin lesions filled with pus. AcneVulgaris Acne vulgaris is a disorder of the pilosebaceous unit (see Chapter 45, Fig. 45-7) that results in formation of dis- crete papular or pustular lesions and may lead to scar- ring. 17–20 Acne can be cosmetically disfiguring and often psychologically disabling. It typically begins around puberty, as a result of increased androgen production. It may begin earlier and persist longer in females; however, FIGURE 46-10. Acute herpes zoster. Panel (A) shows a cutaneous eruption in the rightT7 dermatome. Panel (B) shows a close-up of fresh vesicular lesions. (From Gnann JW, Whitley RJ. Herpes zoster. N Engl J Med. 2002;347:341. Copyright © 2002. Massachusetts Medical Society.)