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February 2007: Psoriasis

What are the different manifestations of psoriasis?

How can nail psoriasis be accurately identified and treated?

How is psoriatic arthropathy best managed?

What are the different manifestations of psoriasis?

How can nail psoriasis be accurately identified and treated?

How is psoriatic arthropathy best managed?

?Psoriasis is a very common condition. in the uk 1-2 per cent of the population are affected – about 1.2 million people.1 The mean age of onset is 28 years. However, 10-15 per cent of new cases occur before the age of 10.

Psoriasis is often thought of as a skin condition. However, the nails and scalp are also commonly affected, and psoriatic arthropathy occurs in 10 per cent of cases.

Psoriasis has a significant impact on the quality of life of patients,2 and can be life-threatening.

The prevalence of psoriasis varies with race. It is most common in white patients.

1 Plaque psoriasis

Plaque psoriasis is typically distributed over the elbows, knees, scalp and lumbosacral areas. It presents as easily identifiable, well-defined, slightly raised red plaques with a thick, silvery scale. The distribution is invariably symmetrical, which is a useful aid to diagnosis.

Surface bleeding caused by gentle scratching is a specific diagnostic sign for the disease.

Certain drugs can exacerbate psoriasis. These include ACE inhibitors, ß-blockers, chloroquine, gold, interferon, lithium, NSAIDs and tetracyclines.3

Current treatment options include emollients, topical steroids, vitamin D analogues and tazarotene.4 Systemic therapies, such as etanercept and efalizumab, may be used in severe cases.5

2 Scalp psoriasis

The scalp is an area commonly affected by psoriasis, and may be the only site affected in some patients. Discrete, symmetrical red plaques occur with considerable scaling on the surface, which causes embarrassing dandruff. The disease can be seen extending onto the skin around the hairline. Unlike many other scalp conditions, psoriasis rarely causes hair loss.

The differential diagnosis includes seborrhoeic dermatitis, tinea capitis, lupus erythematosus and pityriasis amiantacea.

Scalp psoriasis is a chronic condition that is difficult to treat, and patients need support. Typically, patients will return to their clinician repeatedly, despairing at the poor results obtained from treatment.

Topical steroids in the form of scalp applications are easy to apply, but only suppress symptoms. A better treatment option is coconut oil BP, a compound ointment. However, it is unpleasant to apply and patients may require support from a specialist nurse.

3 Plantar pustular psoriasis

Plantar pustular psoriasis typically presents as multiple yellow pustules on the hands and feet. The pustules turn into brown spots. These dry with time and peel off when the skin grows. Although they have the appearance of an infection, their contents are sterile.

Small areas are often affected, as in this case. However, in some patients the entire hands and feet may be involved, resulting in pain and disability. Treatment is difficult, and the response to steroids is poor.

4 Pitting

Between 10 and 55 per cent of patients with psoriasis will exhibit changes to their nails. Nail change with no other manifestations of psoriasis is less common, and occurs in about 5 per cent of cases. The severity of nail psoriasis varies from a few scattered pits on the surface to marked deformity and destruction of the whole nail.

The most important diagnostic sign is the oil drop or salmon patch. This is a translucent, yellow-red discolouration in the nail bed, resembling a drop of oil under the nail plate.

Pitting is more common, and is caused by the loss of parakeratotic cells on the surface of the nail plate. In severe cases this leads to crumbling of the nail plate and matrix, as seen here. One study showed that calcipotriol ointment is useful in the management of this condition.6

5 Subungual hyperkeratosis

Subungual hyperkeratosis affects the nail bed and hyponychium. Excessive hyperproliferation causes a thickening that lifts the nail away from the bed. This is also seen in onychomycosis (fungal infections) – however, in psoriasis, mycology is negative. Psoriasis of the skin is present in most cases.

Scalp treatments can be applied to the nail topically, or systemic treatment may be given.7

6 Onycholysis

Onycholysis presents as a white area of the nail plate, caused by the separation of the nail plate from the underlying structures. It usually starts distally, as in this case, and progresses proximally, causing the distal nail plate to uplift traumatically. Eventually the whole nail may separate, leading to loss of the nail.

The discolouration in this case was caused by secondary colonisation by bacteria or yeast. Psoriasis is not the only cause of this condition; other causes include trauma (made worse by long or false nails), prolonged immersion in water, hyperhidrosis and thyrotoxicosis. Some cases are idiopathic.

A steroidal scalp application can be used topically on the nail in cases of confirmed nail psoriasis.

7 Guttate psoriasis

Guttate psoriasis is a distinctive, acute eruption of multiple salmon pink papules, 1-10mm in diameter with a fine surface scale. Typically occurring on the trunk, the proximal extremities may also be involved, as in this case. It is most common in patients under 30 years, and often occurs two to three weeks after an infection (such as an upper respiratory infection caused by a group A ß-haemolytic streptococcus).8

Guttate psoriasis may herald the onset of generalised psoriasis, or may occur in isolation. It can be a chronic condition unrelated to infection. It is less common than plaque psoriasis, and affects all races and both sexes equally.

Often treatment is not required, as the rash may fade after a couple of weeks. If treatment is indicated emollients can be applied. Topical steroids may be useful in chronic and severe cases.9

8 facial psoriasis

Facial psoriasis is far less common than other forms of the disease. When it does occur, the psychological impact can be devastating. Red plaques develop with a surface scale.

Facial psoriasis does not respond well to topical hydrocortisone, and may require stronger steroids. Calcitriol is currently the only vitamin D analogue licensed for use on the face.10

Differential diagnoses include seborrhoeic dermatitis and lupus erythematosus. Well-defined plaques with tenacious scales occur in the latter, and it has a greater tendency to scar. A biopsy may be required to differentiate between the conditions.

9 Severe psoriasis

In cases of severe, non-responsive psoriasis, treatment with the new anti-TNF immunomodulators may be indicated. In July 2006, NICE issued guidance on their use. The guidance states that etanercept can be used 25mg twice weekly when the following criteria are met:

• Disease severity, as defined by the PASI (psoriasis area severity index), is 10 or more, and the DLQI (dermatology life quality index) is 10 or more.

• The psoriasis has failed to respond to standard treatment, including ciclosporin, methotrexate and PUVA (psoralen and long-wave ultraviolet radiation); or the person is intolerant to, or has a contraindication to, these treatments.

Etanercept should be discontinued in patients who have still failed to respond at 12 weeks. In patients who are intolerant or fail to respond to etanercept, efalizumab may be used.5,11

10 Superficial basal cell carcinoma

GPs should be alert to a single plaque of psoriasis on the trunk. In this case the patient presented with a single plaque on the lower back. It was red, raised and had a surface scale. There were no other lesions, and no past or family history of psoriasis.

A provisional diagnosis of psoriasis was made, but the area failed to respond to conventional treatments.

A biopsy gave the true diagnosis of superficial basal cell carcinoma.

11 Erythrodermic psoriasis

Erythrodermic psoriasis is a potentially fatal condition in which the skin is universally involved with a combination of red (erythroderma) and scaling exfoliative areas.

Vasodilatation causes the skin to become red and lose heat rapidly, making the patient shiver and feel cold. The increased cardiac output required to supplement the vasodilatation may lead to cardiac failure, and dehydration may occur.

The disease may start without a preceding history of psoriasis, but this is rare. There is usually a history of psoriasis becoming erythrodermic secondary to infection, drug allergy or an adverse reaction to topical therapy.

Systemic treatment and hospitalisation is almost always required. Death can occur if the disease is severe or not managed appropriately. This is one of the few dermatological medical emergencies.

12 Psoriatic arthropathy

Psoriatic arthropathy is a sero-negative arthritis that occurs in 10 per cent of patients with skin psoriasis.

There seems to be an increased incidence of psoriatic arthropathy in patients with a family history of psoriasis and HLA-B27. The pattern of disease varies, but usually arthropathy affects the small joints of the hands, especially the distal interphalangeal joints, in an asymmetrical pattern. It is usually mild but chronic, and can be controlled with NSAIDs. Occasionally it can mimic rheumatoid arthritis as a more severe, symmetrical condition. Patients with psoriatic arthropathy have an increased incidence of ankylosing spondylitis.

Plaque psoriasis presents as well-defined, slightly raised

red plaques Figure 1: Plaque psoriasis Scalp psoriasis, unlike many other scalp conditions, rarely causes hair loss Figure 2: Scalp psoriasis Plantar pustular psoriasis typically presents as multiple yellow pustules on the hands and feet Figure 3: Plantar pustular psoriasis Pitting is caused by the loss of parakeratotic cells on the surface of the nail plate Figure 4: Pitting Subungual keratosis. Scalp treatments may be applied to the nail topically Figure 5: Subungual hyperkeratosis Onycholysis. The discolouration in this case is caused by secondary colonisation Figure 6: Onycholysis Guttate psoriasis. Treatment is often not required as the rash may fade after a couple of weeks Figure 7: Guttate psoriasis Facial psoriasis. The psychological impact can be devastating Figure 8: Facial psoriasis Severe psoriasis may require treatment with an anti-TNF immunomodulator Figure 9: Severe psoriasis Superficial basal cell carcinoma. These lesions can be mistaken for psoriasis and GPs should be vigilant Figure 10: Superficial basal cell carcinoma Erythrodermic psoriasis. This is a potentially fatal condition and should be considered a medical emergency Figure 11: Erythrodermic psoriasis Psoriatic arthropathy is usually mild but chronic, and can

be managed with NSAIDs Figure 12: Psoriatic arthropathy Useful information

The Psoriasis Association is a charity with information on psoriasis
www.psoriasis-association.org.uk

The National Psoriasis Foundation
is a non-profit organisation that provides information for patients and clinicians
psoriasis.org/home

The Psoriasis Help Organisation provides links to forums for psoriasis patients
psoriasis-help.org.uk

The Psoriatic Arthropathy Alliance is a charity providing information on psoriasis and psoriatic arthropathy
www.paalliance.org

Author

Dr Nigel Stollery
MB BS
GP, Kibworth, Leicestershire and clinical assistant in dermatology, Leicester Royal Infirmary

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