Porth's Essentials of Pathophysiology, 4e

1180

Integumentary Function

U N I T 1 3

in the center) on the buccal mucosa, and mild to severe photosensitivity. The person commonly has coldlike symptoms, general malaise, and myalgia. In severe cases, the macules may hemorrhage into the skin tissue or onto the outer body surface. This form is called hemorrhagic measles . The course of measles is more severe in infants, adults, and malnourished children. The World Health Organization recommends vitamin A treatment for measles in developing countries to reduce morbidity and mortality. There may be severe complications, includ- ing otitis media, pneumonia, and encephalitis. Antibody titers are determined for a conclusive diagnosis of rube- ola. Measles is a disease preventable by vaccine, and immunization is required by law in the United States. Varicella. Varicella (chickenpox) is a common commu- nicable childhood disease. It is caused by the varicella- zoster virus, which also is the agent in herpes zoster (shingles). The characteristic skin lesion occurs in three stages: macule, vesicle, and granular scab. The macu- lar stage is characterized by development within hours of macules over the trunk, spreading to the limbs, buc- cal mucosa, scalp, axillae, upper respiratory tract, and conjunctiva (Fig. 46-28). During the second stage, the macules form vesicles with depressed centers. The vesi- cles break open and a scab forms during the third stage. Crops of lesions occur successively, so that all three forms of the lesion usually are visible by the 3rd day of the illness. Mild to extreme pruritus accompanies the lesions, which can lead to scratching and subsequent develop- ment of secondary bacterial infections. Chickenpox also is accompanied by coldlike symptoms, including cough, coryza, and sometimes photosensitivity. Mild febrile states usually occur, typically beginning 24 hours before lesion outbreak. Side effects, such as pneumonia, septic complications, and encephalitis, are rare. Varicella in adults may be more severe, with a pro- longed recovery rate and greater chances for devel- opment of varicella pneumonitis or encephalitis.

Immunocompromised persons may experience a chronic, painful form of the infection. Despite breakthrough cases and lower efficacy rates overall than in other vaccines, live attenuated varicella vaccine has been demonstrated to have dramatically decreased varicella morbidity and mortality since 1995, when the vaccine was introduced in the United States. 72 The vaccine is most effective in children under 10 years of age. 72 One dose of the vaccine is required by law in the United States; however, a second dose is now rec- ommended to address what is called primary vaccine failure . It is believed that a single dose of varicella vac- cine may only prime the host response, without induc- ing protective immunity. Outbreaks of mild cases of varicella, called breakthrough varicella, have occurred in vaccinated populations. The breakthrough infection is difficult to diagnose because the maculopapular rash does not have the classic sign of vesicles. Skin Manifestations and Disorders in the Elderly Elderly persons experience a variety of age-related skin disorders and exacerbations of earlier skin problems. Aging skin is believed to involve a complex process of actinic (solar) damage, normal aging, and hormonal influences. Actinic changes primarily involve increased occurrence of lesions on sun-exposed surfaces of the body. Normal Age-Related Changes Normal skin changes associated with aging are seen on areas of the body that have not been exposed to the sun. They include thinning of the dermis and the epidermis, diminution in subcutaneous tissue, a decrease and thick- ening of blood vessels, and a decrease in the number of melanocytes, Langerhans cells, and Merkel cells. The keratinocytes shrink, but the number of dead keratin- ized cells at the surface increases. This results in less pad- ding and thinner skin, with color and elasticity changes. The skin also loses its resistance to environmental and mechanical trauma. Tissue repair takes longer. With aging, there is also less hair and nail growth, and there is permanent hair pigment loss. Hormonally, there is less sebaceous gland activity, although the glands in the facial skin may increase in size. Hair growth reduc- tion also may be hormonally influenced. Although the reason is poorly understood, the skin in most elderly persons older than 70 years of age becomes dry, rough, scaly, and itchy. When there is no underlying pathologic process, it is called senile pruritus . Itching and dryness become worse during the winter, when the need for home heating lowers the humidity. The aging of skin, however, is not just a manifesta- tion of age itself. Most skin changes associated with the elderly are the result of cumulative actinic or environ- mental damage. For example, the wrinkled, leathery look of aged skin, as well as odd scars and ecchymotic spots, are due to solar elastotic degenerative change.

FIGURE 46-28. Blisterlike lesions of varicella (i.e., chickenpox) on the face of a young child. (From the Centers for Disease Control and Prevention Public Health Image Library. No. 10486. Courtesy of John Noble, Jr.)