Scaly skin diseases

Acknowledgements

Developed in collaboration with the University of Auckland Goodfellow Unit in 2007.

Author: Hon A/Prof Amanda Oakley, Dermatologist, Hamilton, New Zealand, 2009.혻혻

Images have been sourced from the following:

  • Hon Assoc Prof Amanda Oakley
  • The Department of Dermatology, Health Waikato
  • Prof Raimo Suhonen (Finland)

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Acute forms of psoriasis

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Learning objectives

  • Describe the clinical features and management of acute forms of psoriasis

Note. You should have already read the overview page about psoriasis.

Clinical features

Acute guttate psoriasis
Acute guttate psoriasis is a common presentation of psoriasis in children and adolescents.

  • Associated with HLA-CW6 antigen
  • Acute onset one to three weeks after streptococcal throat infection
  • Streptococcal super-antigens may resemble an antigen on keratinocytes
  • Showers of small erythematosus papules, appear over about two weeks
  • These develop scaling within a few days
  • Lesions are prominent on trunk but may also affect scalp, face and limbs
  • May completely remit within a few months or chronic plaques may follow

Erythrodermic psoriasis
Erythrodermic psoriasis refers to very extensive or whole-body psoriasis and requires urgent specialist dermatologist review.

  • Red, thickened and often scaly skin
  • May arise acutely as exanthematic flare
  • Although often well tolerated, may cause fluid imbalance, temperature disturbance and high output cardiac failure
  • Marked peeling may develop on palms and soles

Generalised pustular psoriasis
Generalised pustular psoriasis (von Zombusch psoriasis) requires urgent specialist dermatologist review.

  • Rare acute eruption of subcorneal pustules on an erythematous base
  • May complicate chronic plaque psoriasis or arise spontaneously
  • May cause severe malaise, electrolyte imbalance including hypocalcaemia, and temperature dysregulation

Rare subtypes of subacute or chronic generalised pustular psoriasis include:

  • Subcorneal pustular dermatosis (Sneddon-Wilkinson disease)
  • Erythema annulare centrifugum-like variant
  • Impetigo gestationis (pustulosis arising in pregnancy)

Although often idiopathic, flares can be precipitated by:

  • Withdrawal of systemic steroids (or excessive potent topical steroids)
  • Drugs, including salicylates, iodine, lithium, phenylbutazone, oxyphenbutazone, trazodone, penicillin, hydroxychloroquine, calcipotriol, interferon-alpha, and recombinant interferon-beta
  • Strong, irritating topicals, including tar, dithranol, steroids under occlusion, and zinc pyrithione
  • Infections
  • Sunlight or phototherapy especially sunburn
  • Cholestatic jaundice
  • Hypocalcemia

Differential diagnosis

Guttate psoriasis may be confused with:

  • Discoid dermatitis (more itch, vesicles, dry rather than plate-scale)
  • Tinea corporis (elevated border, slowly extending edge, positive mycology)
  • Pityriasis rosea (herald patch, fir-tree distribution of oval plaques, trailing scale)

Erythrodermic psoriasis may be confused with:

  • Erythrodermic atopic dermatitis (intense pruritus, exudative ++)
  • Drug eruption (due to drug commenced within prior 8 weeks)
  • Pityriasis rubra pilaris (cephalo-caudal spread, follicular prominence)

Generalised pustular psoriasis may be confused with:

  • Acute generalised exanthematic pustulosis (drug eruption that rapidly settles with withdrawal of drug, also known as ?쁀GEP??and more common in those with known psoriasis)
  • Bacteraemia and bacterid: cutaneous pustules arising during gram positive and gram negative septicaemia
  • Infected generalised atopic and/or seborrheic dermatitis
  • Pityriasis rubra pilaris
  • Reiter syndrome
  • Folliculitis

Investigations

Investigations indicated in acute forms of psoriasis may include:

  • Skin swabs for bacteriology: to identify secondary infection (Staph. aureus and Strept. pyogenes)
  • Throat swab for beta haemolytic streptococcus
  • Skin biopsy to confirm diagnosis
  • Blood count, electrolytes, calcium, liver function in acutely unwell patients

Management

Mild guttate psoriasis is usually managed with topical agents.

  • Calcipotriol cream or ointment for limited numbers of scaly plaques
  • Mild topical steroids for itch, e.g. hydrocortisone lotion
  • Emollients

If guttate psoriasis is too extensive or severe to be effectively managed with topical treatments alone, refer to a dermatologist for phototherapy and/or systemic treatment.

Treatment for erythrodermic and generalised pustular psoriasis includes:

  • Hospitalisation for supportive care including intravenous fluids and temperature regulation
  • Bland emollients and cooling wet dressings
  • Bed rest
  • Low-dose methotrexate, ciclosporin or acitretin
  • Treatment of complications (for example antibiotics, diuretics, nutritional support)

Oral corticosteroids should be avoided because withdrawal risks worsening of the psoriasis. However, sometimes they are the only treatment that helps, in which case specialist care is mandatory.

Topical tar preparations and phototherapy should also be avoided in the acute phase of erythrodermic or generalised pustulosis.

Activity

What is the evidence that antistreptococcal treatment is helpful in the management of psoriasis?

Related information

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