9: DERMATOLOGY

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CHAPTER 9 DERMATOLOGY

Benign superficial lumps
Skin malignancies
Acne
Hidradenitis suppurativa
Rosacea
Bacterial skin infections
Viral skin infections
Fungal skin infections
Generalised pruritus
Hair loss
Excessive sweating
Eczema
Psoriasis
Keratosis pilaris
Head lice
Scabies
Other skin infestations
Allergic rashes/urticaria
Venous ulcers
Arterial ulcers

BENIGN SUPERFICIAL LUMPS

Benign superficial lesions, including moles, seborrhoeic warts, skin tags and sebaceous cysts, can be removed easily in the surgery by one or other of the following: curettage, cautery, cryotherapy or excision.

SKIN MALIGNANCIES

MALIGNANT MELANOMA

A GP might expect to see one malignant melanoma every 5 years in a list size of 2000 patients. The only effective treatment for melanoma is excision. It is therefore essential that an early diagnosis is made, while the tumour is still thin. Melanomas are extremely fast growing, developing over only a few months.

Diagnosis

History.

Ask about the following risk factors:

• A mole changing in shape or colour.
• Large numbers of normal naevi, particularly with a family history of malignant melanoma.
• A past history of primary malignant melanoma or severe sunburn.
• General skin type: people with blonde/red hair colour and poorly tanning skin are at greater risk.

Tip

Major features strongly suggestive of malignancy

• Change in size or new lesion.
• Irregular shape.
• Irregular colour.

Examination

Also look for other suspicious features, e.g.:

• inflammation
• crusting or bleeding
• changes in sensation.

Management

All suspicious moles should be referred immediately for wide excision.

Patients with clearly benign lesions should be reassured, and prevention should be discussed; excise the lesion if appropriate.

Long-term prevention.

High-risk patients should be advised to examine themselves regularly and to know the signs of malignancy. They should protect themselves from the sun, avoid sunbeds and use sunscreens that protect against UVA and UVB with a sun protection factor of >15, e.g. Uvistat 20. Sunscreens can be prescribed on FP10 only for patients with photodermatoses who require high protection (SPF >15). Prescriptions should be marked with ‘ACBS’ (Advisory Committee on Borderline Substances).

Low-risk patients should also be advised to protect themselves from the sun and to use sunscreens with an SPF of at least 10.

SOLAR KERATOSES

These are more common on sun-damaged skin and in the elderly. They look like dry, cracked plaques. They have very low malignant potential, and can be treated with cryotherapy or fluorouracil cream bd for 2–4 weeks.

BASAL CELL CARCINOMA (RODENT ULCER) AND SQUAMOUS CELL CARCINOMA

These are commonly related to sun exposure. They both have raised irregular edges and may be ulcerated. The BCC may have a pearly border. These should be referred early for excision, radiotherapy or cryotherapy.

ACNE

More then half of British teenagers develop acne severe enough to warrant therapy. Acne can cause great emotional distress, and is usually easily treatable. It is exacerbated by hot, sweaty conditions, and any cosmetics used should be light and non-greasy. Sensitivity and understanding are important. Most sufferers will have already self-treated with OTC preparations.

Diagnosis

History.

Ask about past and present OTC and prescribed treatments.

Examination.

Look for comedones, erythematous papules and pustules on the face, chest or back. There may be pitted scars.

Tip

Most patients need to be reassured that their acne is very largely unrelated to the nature of their diet.

Management

Mild acne.

These topical preparations should be applied to the whole affected area after washing the skin, and are likely to cause some degree of skin irritation initially.

Inflammatory lesions

• Benzoyl peroxide (1–10%). Start treatment with lower strength preparations.
• Topical antibiotics (clindamycin, erythromycin or tetracycline).
• Azelaic acid.

Non-inflammatory lesions (comedones)

• Topical retinoids (e.g. adapalene, tretinoin).
• Topical retinoids may be used in addition to benzoyl peroxide or topical antibiotics. If used together, apply each once a day at different times.

Moderate acne

Oral antibiotics.

These may be used in addition to topical treatments. Improvement may take up to 6 weeks and maximum improvement occurs at 3–4 months. It is worth trying an alternative oral antibiotic if the response to the first is inadequate after 3–4 months. Treatment may continue for several years, if necessary.

• Oxytetracycline 500 mg bd for 3 months, then reduced to 250 mg bd.
• Erythromycin 500 mg bd for 3 months, then reduced to 250 mg bd. (Both antibiotics can be increased to 1–2 g per day, if necessary.)
• Minocycline and doxycycline are only taken once a day. They are significantly more expensive. They are less affected by food.

The combined oral contraceptive in acne

The COC can be started in a patient who has been taking long-term antibiotics for acne without the need for extra contraceptive precautions. If the patient is already on the COC when first starting antibiotics for acne, or when switching to a different antibiotic, additional contraception should be used for the first 2 weeks to allow antibiotic resistance to develop among the bowel flora which are responsible for recycling oestrogens.

Hormonal treatment

• Dianette: this contains cyproterone acetate, an antiandrogen. It is the most effective oral contraceptive for acne, and if used for contraception, a prescription charge can be avoided by writing ‘for contraception’ on the prescription. It can be used with or without oral antibiotics and/or topical treatments.
• COC: other COCs that tend to improve acne are those with a relatively non-androgenic progestogen, e.g. Marvelon, Cilest, Femodene, Minulet and Yasmin.

Severe acne.

(Also acne that fails to respond to the above treatment.) Refer for oral isotretinoin. This is expensive, teratogenic and has a high side-effect profile. All females of child-bearing age should be using effective contraception (usually Dianette) and should have LFTs and fasting lipids checked before their dermatology appointment.

HIDRADENITIS SUPPURATIVA

This causes chronic papules and pustules, with scarring, in the axillae and/or groins. It can be treated with long-term oxytetracycline 500 mg bd. Some patients require plastic surgery.

ROSACEA

Topical steroids aggravate rosacea.

This is characterised by chronic, shiny facial erythema, especially over the cheeks and central forehead. It is exacerbated by heat, sun exposure, spicy food and alcohol. There may be papules and pustules. It occurs most commonly in middle-aged women. It can be treated with long-term oxytetracycline 500 mg bd, reducing, if possible, to a maintenance dose of 250 mg daily. Treatment may be continuous or intermittent. Metronidazole gel applied twice daily is an alternative treatment, and may be used, if necessary with oral antibiotics.

BACTERIAL SKIN INFECTIONS

CELLULITIS/ERYSIPELAS (STREPTOCOCCAL)

These two conditions may coexist. Erysipelas is a superficial infection, causing sharply demarcated tender erythematous areas. Cellulitis causes deeper infection, involving the subcutaneous tissues. Treatment is with oral penicillin (and, in the case of cellulitis, flucloxacillin, in case of staphylococcal involvement) or erythromycin alone if penicillin-allergic for 7–10 days. Advise bed rest. Occasionally, admission may be required for treatment with intravenous antibiotics.

BOILS (STAPHYLOCOCCAL)

See p. 198.

FOLLICULITIS (STAPHYLOCOCCAL)

This is sometimes seen in patients treated with topical steroid ointments for eczema, and as a result of shaving or skin friction. It should be treated with mild antiseptics, e.g. povidone-iodine, or, if severe, with oral flucloxacillin.

IMPETIGO

Impetigo is a common infectious condition of the skin, caused by Staphylococcus.

Diagnosis

History.

Impetigo starts as a slough, which hardens to form a yellow crust. It is usually painless and occurs anywhere on the body, but is most common on the face.

It often complicates other skin problems that involve a breach of the skin surface, e.g. cracked lips, cold sores, eczema or grazes.

Cold sores can be indistinguishable from impetigo.

Management

• Fusidic acid cream tds rubbed on the crusts will help to soften them and prevent the further multiplication of bacteria.
• For widespread or stubborn lesions, use flucloxacillin 250 mg qds for 5 days.
• Erythromycin is effective in patients allergic to penicillin.

Tip

Inform the patient that impetigo is contagious and an individual towel and flannel should be used. It is not necessary to avoid school once treatment has started.

ERYTHRASMA

This usually presents as a brown, slightly scaly area in the armpits or groins. It is asymptomatic and is produced by a Corynebacterium

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