Scabies Human scabies is a highly contagious disease caused by the mite Sarcoptes scabiei var. hominis . The mite is an obligate parasite to humans. Scabies is not primarily a sexually transmitted disease, but sexual transmission does occur ( Table 15.1 ). High-risk persons include men who have sex with men. There is no evidence that mites can transmit infection with the human immunodeficiency virus (HIV).…

The word exanthem means a skin eruption that bursts forth or blooms. Exanthematous diseases are characterized by widespread, symmetric, erythematous, discrete, or confluent macules and papules that initially do not form scale. Exanthematous disease is one of the few diseases for which the term maculopapular is an appropriate descriptive term. Other lesions, such as pustules, vesicles, and petechiae, may form, but most of the exanthematous diseases…

Dermatophyte Fungal Infections These dermatophytes include a group of fungi (ringworm) that under most conditions have the ability to infect and survive only on dead keratin (that is, the top layer of the skin – the stratum corneum or keratin layer), the hair, and the nails. They cannot survive on mucosal surfaces such as the mouth or vagina where the keratin layer does not form. Very…

Warts Warts are benign epidermal neoplasms that are caused by human papillomaviruses (HPVs), which are small DNA viruses. There are more than 100 different types of HPVs, and new types are discovered each year. HPVs infect epithelial cells of the skin, mouth, esophagus, larynx, trachea, and conjunctiva and cause both benign and malignant lesions. They induce a variety of infections ( Table 12.1 ). TABLE 12.1…

Genital Warts Virus Types Human papillomavirus (HPV) causes warts and anogenital malignancy. HPV can reside in epithelial basal cells and lead to subclinical or latent infection. Numerous types of HPV viruses have been identified. These HPV types also are categorized into low-, intermediate-, and high-risk groups. Detection of high-risk genotypes ( n = 13) from genital specimens is considered a major determinant associated with the development…

Sexually Transmitted Disease Presentations Sexually transmitted diseases (STDs) can present as follows: Genital ulcers or sores Urethral discharge Vaginal discharge Cervical infection Lower abdominal pain Inguinal bubo Scrotal swelling Rectal or pharyngeal inflammation Papules The Centers for Disease Control and Prevention criteria for the treatment of all STDs is presented in Table 10.1 . An overview of these diseases and their World Health Organization (WHO) syndromic…

Skin Infections The two Gram-positive cocci Staphylococcus aureus and group A beta-hemolytic streptococci account for the majority of skin and soft tissue infections (SSTIs). S. aureus invades skin and causes impetigo, folliculitis, cellulitis, and furuncles. Elaboration of toxins by S. aureus causes the lesions of bullous impetigo and staphylococcal scalded skin syndrome. The streptococci are secondary invaders of traumatic skin lesions and cause impetigo, erysipelas, cellulitis,…

Papulosquamous diseases are a group of disorders characterized by scaly papules and plaques. These entities have little in common except the clinical characteristics of their primary lesion. A complete list of diseases characterized by scaly plaques appears in the section on primary lesions in Chapter 1 . The major papulosquamous diseases are described here. Psoriasis Psoriasis occurs in 2% to 3% of the general adult population,…

Acne Acne, a disease of the pilosebaceous unit, appears in males and females who live in westernized societies and are near puberty, and in most cases acne becomes less active as adolescence ends. The intensity and duration of activity vary for each individual. The disease may be minor, with only a few comedones or papules, or it may occur as the highly inflammatory and diffusely scarring…

Urticaria, also referred to as hives or wheals, is a common and distinctive cutaneous reaction pattern. Hives may occur at any age; up to 20% of the population will have at least one episode. Hives may be more common in atopic patients. Urticaria is classified as acute or chronic. The majority of cases are acute, lasting from hours to a few weeks. Angioedema frequently occurs with…

The term atopy was introduced years ago to designate a group of patients who had a personal or family history of one or more of the following diseases: hay fever, asthma, very dry skin, and eczema. Atopic dermatitis (AD) is a chronic, pruritic inflammatory skin disease that occurs most frequently in children, but also affects many adults. It follows a relapsing course. AD is often associated…

Contact dermatitis is an eczematous dermatitis caused by exposure to substances in the environment. Those substances act as irritants or allergens and may cause acute, subacute, or chronic eczematous inflammation. To diagnose contact dermatitis one must first recognize that an eruption is eczematous. Contact allergies often have characteristic distribution patterns indicating that the observed eczematous eruption is caused by external rather than internal stimuli. Elimination of…

Eczema (eczematous inflammation) is the most common inflammatory skin disease. Although the term dermatitis is often used to refer to an eczematous eruption, the word means inflammation of the skin and is not synonymous with eczematous processes. Recognizing a rash as eczematous rather than psoriasiform or lichenoid, for example, is of fundamental importance if the clinician is to effectively diagnose skin disease. Here, as with other…

Topical Therapy A wide variety of topical medications are available for treating cutaneous disease (see Formulary). Specific medications are covered in detail in the appropriate chapters, and the basic principles of topical treatment are discussed here. The skin is an important barrier that must be maintained to function properly. Any insult that removes water, lipids, or protein from the epidermis alters the integrity of this barrier…

Skin Anatomy The skin is divided into three layers: the epidermis, the dermis, and the subcutaneous tissue. The skin is thicker on the dorsal and extensor surfaces than on the ventral and flexor surfaces. Epidermis The epidermis is the outermost part of the skin; it is stratified squamous epithelium. The thickness of the epidermis ranges from 0.05 mm on the eyelids to 1.5 mm on the palms and…