chapter 42 Skin
DIAGNOSIS
• History—in addition to the history of the condition, questions relating to general health are also needed. Past medical history, family history, allergic history, a nutritional assessment, including supplements, and medications are all important. Listen to patients, as they often have perceptions about their skin and ideas that provide clues to the causes or triggers for the condition.
• Examination
• Dermatology is a visual branch of medicine, and in order to ensure accurate diagnosis, examination requires a bright light and good magnification.
• Dermoscopy is a valuable examination tool for pigmented lesions. An ultraviolet Wood’s lamp can cause fungal infections and erythrasma to fluoresce.
• Accurate description of lesions or skin—an accurate description (Table 42.1) requires careful observation and often leads directly to the diagnosis. A dermatology atlas and comprehensive text are helpful.
• Special tests—take the time and make the effort to do the tests. Investigations are:
• punch, shave or incisional biopsy. These are simple procedures that take little extra time and often make or confirm a diagnosis. It is important to provide a brief clinical outline, a description of the lesion and, if possible, a differential diagnosis for the histopathologist, as microscopic appearances can be equivocal.
• Diagnosis will arise from the above systematic approach. Remember that the skin is a reflector of systemic conditions.
TREATMENT PLAN
• Prevention—where triggers are identifiable; for example, avoidance of arginine-rich foods (peanuts, almonds and chocolate) with herpetic infections; management of sun exposure to minimise solar sun damage while ensuring adequate sun exposure to manufacture vitamin D in the skin.
• Surveillance—Hippocrates said to ‘Make a habit of two things—to help or at least to do no harm’. The positive diagnosis of benign or self-limiting conditions such as pityriasis rosea, keratosis pilaris, granuloma annulare or toxic viral rashes is important, as they often require no intervention.
• Self-help and general remedies that aim to improve the patient’s general health and benefit the condition. For example:
• Reducing immune stressors can reduce the threshold to autoimmune disease that affects or reflects in the skin. These diseases include vitiligo, melanoma, halo naevus, idiopathic thrombocytopenic purpura, Hashimoto’s thyroiditis, systemic lupus erythematosus, scleroderma and diabetic skin disease. Stressors that reduce a patient’s adaptive capacity include emotional stress (including anxiety and depression), chemical load, allergic load, hormonal imbalance, fatigue, endocrine disease, chronic viral infections and nutritional deficiencies (zinc, iron, vitamin D, vitamin B12 or folic acid). These stressors are common and need to be addressed.
• Pharmacological relief is important—a teenager with severe acne can try multiple nutritional and topical measures but needs treatment with a high probability of a rapid response. This will often include topical as well as oral treatments.
• Surgical excision is still the treatment of choice for the majority of skin cancers. Excision provides a specimen, which is always sent to pathology. The dermatopathologist will confirm or make the diagnosis and establish the presence of a margin of safety around the malignant lesion.
IMPORTANT PITFALLS IN SKIN MANAGEMENT
• Remember to take skin conditions seriously. Most are not fatal but many cause angst and suffering, or low mortality with high morbidity. Take the trouble to assess the impact of the condition on the patient. For example, most young people with moderate acne experience significant loss of confidence, depression or even difficulty gaining employment.
• Work for a positive diagnosis before committing to long-term treatment. For example, is it psoriasis, eczema or fungal?
SPECIFIC SKIN CONDITIONS
ECZEMA
Eczema is the most common skin reaction. It is an inflammatory disorder and the term is interchangeable with dermatitis, although sometimes ‘dermatitis’ is used when the cause is external or exogenous (Box 42.1).
Contact or exogenous eczema
• Irritant contact—occurs whenever irritant materials are in prolonged contact with the skin. This is not an allergy and does not reflect individual sensitivity. It is a direct irritant effect of substances such as detergent, petrol or solvents. Irritant contact dermatitis of the hands is the most common occupational disease.
• Allergic contact—occurs when there is an allergic reaction to an agent in contact with the skin (Box 42.2). There are many causes. These may be suspected from the history and confirmed by patch testing if necessary.
• Napkin dermatitis is a specific form of irritant contact dermatitis following prolonged contact with urine and faeces.
Constitutional or endogenous eczema
• Pompholyx or dyshidrotic eczema—this is a common hand or foot eczema characterised by small blisters on the palms or soles, especially at the margins, that burst and heal with peeling. Because the skin is thick, inflammatory fluid is trapped in the skin, leading to this characteristic appearance. A potent topical steroid ointment is required.
• Discoid or nummular eczema—the pattern of one or more oval or coin-shaped plaques of eczema is characteristic. The cause is unknown but lesions may occur on any part of the body, particularly on the legs.
• Asteatotic eczema or eczema craquelé—a dry and itchy form of eczema on the legs that produces a ‘crazy paving’ type of appearance. It is related to dry skin (xerosis) and is common later in life.
• Seborrhoeic eczema—a red, itchy, scaling rash that commonly affects the scalp and midline areas of the face, including around the nose and between the eyebrows. The ears may also be involved, and occasionally areas on the central chest and axillae are affected. It is thought to be caused by sensitivity to a yeast, Malassezia. The eyelids often have scales and redness (blepharitis).
Atopic eczema
Atopic eczema can be likened to a slow-burning scrub fire. It is much more than a steroid-responsive dermatosis. Each patient needs to be managed with an appreciation of the causes, triggers and individual patterns of their disease.
The cause of atopic eczema is probably multifactorial: genetic, immunological and environmental.
Prevention
(See also Ch 55, Child health and development.)
• Pregnant mothers with a family history of atopy or allergies should have their diet discussed. Avoidance of specific foods such as egg white or shellfish in pregnancy may reduce the risk of atopic disease in the baby, but there should also be discussion of the patient’s food intake to ensure that there is a good variety of foods and moderation of intake of foods where there has been a family problem.
• A good level of antioxidant intake during pregnancy reduces allergic disease in the first 2 years of life.
Treatment
These approaches are directed towards young children, but are adaptable to all age groups.
• Once a young child has atopic eczema, reducing dust in the bedroom and removing pets and feathers are precautionary measures.
• Avoiding contact with skin infections, especially cold sores or herpetic infections, helps to prevent infections that cause more severe eruptions in eczematous skin.
• Treat dry skin—like dry leather, dry skin does not respond well to soaps or detergents, and needs oil or moisturising preparations to keep it soft and healthy. How well would leather shoes respond to regular washing with soap and hot water? Similarly, eczematous skin is best cleansed with cooler water and minimal use of a soap substitute or cream.
• Emollients or moisturisers are useful for greasing dry skin (xerosis). Although many commercial brands have petrochemical bases, they usually work well in practice. Often these base preparations have added ingredients such as oils or colloidal oatmeal. Plant oils can also be useful topically, and include evening primrose, vitamin E, rosehip and coconut oils. Emollients soak into the skin within 2 hours and need to be used frequently to moisturise the skin effectively. These oils can also be applied as ointments or creams. Creams contain water and therefore also preservatives, which have the potential for sensitisation. The more greasy the emollient the more effective, but often also the less cosmetically acceptable.
• Ensure there are adequate oils in the diet. Fish oil (adult dose 1000 mg caps, four daily) or flaxseed oil (especially for vegetarians), which is a comparable omega-3 fatty acid. Omega-6 fatty acids such as evening primrose oil can be used in smaller doses and also applied topically as an emollient. Dietary olive oil can be used for dressings, salads and cooking.
• Infection is important in atopic eczema. Up to 80% of eczema is colonised by pathogenic bacteria, especially Staphylococcus aureus. The more severe the dermatitis, the denser the infection. S. aureus causes direct irritation or exotoxin immunological sensitisation. Bacteria belong on the outside of the skin but in eczema they readily penetrate the skin, causing inflammation and itching. Scratching then ploughs in more bacteria. Antiseptic measures or topical antibiotics can help eradicate infection and aid repair of the barrier function of the skin.
Infection control measures in atopic eczema:
• Condy’s crystals (KMnO4)—1:8000 solution gives a light-pink solution in the bath and is a safe and effective antiseptic
• Anti-inflammatory agents such as topical corticosteroid ointments or pimecrolimus cream (for the face) reduce inflammation and restore the barrier function of the skin, moisture and normal texture.
• Know the forms and doses of topical medications. Common forms: ointments are oil in oil, creams are oil in water, and lotions contain still more water.
• Different potencies of topical corticosteroids are used for different areas and age groups. Use only hydrocortisone on the face, and only the more potent fluorinated topical corticosteroids on the hands and feet where the skin is thick. Hydrocortisone can be effective on the trunk and limbs in children.
• How much ointment will be needed? To work out the dose needed, use the ‘rule of hand’ (Fig 42.1).4 Four hand areas (using the area under the flat of the hand) requires one gram of ointment per treatment. For example, if ointment is being used daily over eight hand areas, this is 2 grams daily, and a 15-gram tube will last 1 week. It is important to prescribe an adequate quantity to last until the next review.
• Put out the fire. Cool down the inflammation of eczema. Eat, drink, dress, sleep, bathe, shower and think cool. Inflammatory conditions are like a grass fire—easier to prevent than to put out. Turning down the central heating, avoiding heating foods such as spices, sleeping and dressing cool, bathing or showering cool and keeping a cool head, all help. Traditional Chinese medicine incorporates concepts of heat in diagnosis and treatment.
• Nutritional supplements:
• omega-3 fatty acids—replace arachidonic acid and lead to reduced levels of inflammatory mediators and IgE. Sources are:
deep-sea cold water fish such as salmon, sardines, herrings, mackerel or fish oil capsules 1000 mg (adult dose: four daily)