Localised lesions with epidermal changes

Psoriasis, seborrhoeic dermatitis, atopic eczema, and contact dermatitis can all present with localised lesions.

Psoriasis may affect only the flexures, occur as a genital lesion, or affect only the palms. The lack of itching and epidermal changes with a sharp edge help in differentiation from infective or infiltrative lesions.

Seborrhoeic dermatitis can occur in the axillae or scalp with no lesions of other areas.

In atopic eczema the "classical" sites in children—flexures of the elbows and knees and the face—may be modified in adults to localised vesicular lesions on the hands and feet in older patients. Some atopic adults develop severe, persistent generalised eczematous changes.

Contact dermatitis is usually localised, by definition, to the areas in contact with irritant or allergen. Wide areas can be affected in reactions to clothing or washing powder, and sometimes the reaction extends beyond the site of contact.

Fungal infections

Apart from athlete's foot, toenail infections, and tinea cruris (most commonly in men), "ringworm" is in fact not as common as is supposed. The damp, soggy, itching skin of athlete's foot is well known. An itching, red diffuse rash in the groin differentiates tinea cruris from psoriasis. However, erythrasma, a bacterial infection, may be confused with seborrhoeic dermatitis and psoriasis—skin scrapings can be taken for culture of Corynebacterium minutissimum or, more simply, coral pink fluorescence shown with Wood's light. The scaling macules from dog and cat ringworm (Microsporum canis) itch greatly, whereas the indurated pustular, boggy lesion (kerion) of cattle ringworm is quite distinctive.

Fungal infection of the axillae is rare; a red rash here is more likely to be due to erythrasma or seborrhoeic dermatitis.

Tinea cruris is very unusual before puberty and is uncommon in women.

In all cases of suspected fungal infection skin scrapings should be taken on to black paper, in which they can be folded and sent to the laboratory. Special "kits" are available, which contain folded black paper and Sellotape strips on slides for taking a superficial layer of epidermis.

Lupus erythematosus

There are two forms of this condition: discoid, which is usually limited to the skin, and systemic, in which the skin lesions are associated with renal disease, arthritis, and other disorders. There is also a subacute type with limited systemic involvement.

Desquamation
Flexural seborrhoeic dermatitis
Corynebacterium minutissimum (erythrasma)

Lupus erythematosus

Systemic

Discoid

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Malar erythema may

Thickened plaques with

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atrophy and

follicular keratosis

Men : Women

Men : Women

1 : 9

1 : 3

+++

Photosensitivity

++

++++

Systemic disease

+++

Antinuclear antibodies

+/-

Characteristics of systemic and discoid lupus erythematosus

Characteristics of systemic and discoid lupus erythematosus

Systemic lupus erythematosus, which is much more common in women than men, can be an acute, fulminating, multisystem disease that requires intensive treatment, or a more chronic progressive illness. Characteristically there is malar erythema with marked photosensitivity and a butterfly pattern. It may be transient. There may be scalp involvement as well with alopecia and also telangiectasia of the perifungal blood vessels. Mouth ulcers may also be present. Systemic involvement may cause nephritis, polyarteritis, leukopenia, pleurisy, myocarditis, and central nervous system involvement.

Systemic lupus erythematosus can present in many forms and imitate other diseases. The facial rash can resemble rosacea, cosmetic allergy, or sun sensitivity. Systemic involvement may present with lassitude, weight loss, anaemia, arthritis, renal failure, dyspnoea, or cardiac signs among others.

Criteria for making a diagnosis of systemic lupus erythematosus have been established, of which at least four must be present.

In the subacute variety there is less severe systemic involvement, with scattered lesions occurring on the face, scalp, chest, and arms.

Treatment is with systemic steroids, with immunosuppressive agents if necessary. Antimalarial drugs, such as hydroxychloroquine, are more effective in the subacute type.

In discoid lupus erythematosus there are well defined lesions with a combination of atrophy and hyperkeratosis of the hair follicles giving a "nutmeg grater" appearance. They occur predominantly on the cheeks, nose, and forehead. It is about three times as common in women as men, which is a lower ratio than in the systemic variety. There is a tendency for the skin lesions to gradually progress and to flare up on sun exposure. It is rare for progression to the systemic type to occur.

Treatment is with moderate to very potent topical steroids and hydroxychloroquine by mouth, together with suitable sun

Fixed drug eruptions

Generalised drug eruptions are considered under erythema, but there is a localised form recurring every time the drug is used. There is usually a well defined, erythematous plaque, sometimes with vesicles. Crusting, scaling, and pigmentation occur as the lesion heals. It is usually found on the limbs, and more than one lesion can occur.

Criteria for diagnosing systemic lupus erythematosus

• Discoid plaques

• Photosensitivity

• Renal disease

• Neurological disease

• Haematological changes

• Immunological changes

• Antinuclear antibodies

Systemic lupus erythematosus—subacute
Discoid lupus erythematosus

Erythema

Bowen's disease or intraepidermal carcinoma

Solitary lesion, slowly growing with sharp uneven outline?

With epidermal changes, not itching?

Yes

Well defined edge

and some scaling?

Bowen's disease or intraepidermal carcinoma

Fixed drug eruption:

Barbiturates

Sulphonamides

Chlordiazepoxide

Phenolphthalein

Dapsone

Tetracycline

Solitary lesion, slowly growing with sharp uneven outline?

Oedematous epidermis

Well defined edge, no scaling?

Discoid lupus erythematosus

- 'nutmeg grater' surface

Hyperkeratosis and atrophy with depression of surface of lesion on sun exposed skin?

With epidermal changes, itching?

Yes

With vesicles and poorly defined edge?

No

Thickening hyperkeratotic epidermis due to rubbing?

No

Papules of violaceous colour with white striae and hyperkeratosis—look for lacy white net-like lesions, sometimes with ulcers on oral mucosa. Blisters may be present?

Non-specific erythematous lesions on trunk and limbs—look for "burrow" on wrists, ankles, breasts and genital areas. Older lesions form residual papules?

Erythematous palpable lesions with little epidermal change?

Urticaria

Recurrent itching lesions?

Lichen simplex

Papules of violaceous colour with white striae and hyperkeratosis—look for lacy white net-like lesions, sometimes with ulcers on oral mucosa. Blisters may be present?

Lichen planus

No

Inflammed lesion with advancing scaling edge, especially in groin?

No

Non-specific erythematous lesions on trunk and limbs—look for "burrow" on wrists, ankles, breasts and genital areas. Older lesions form residual papules?

Fungal injection

Fixed, developing and recurring over weeks or months?

Vasculitis

Fixed, developing and recurring over days?

Lupus erythem-atosus

Causes of epidermal rashes

How To Deal With Rosacea and Eczema

How To Deal With Rosacea and Eczema

Rosacea and Eczema are two skin conditions that are fairly commonly found throughout the world. Each of them is characterized by different features, and can be both discomfiting as well as result in undesirable appearance features. In a nutshell, theyre problems that many would want to deal with.

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