8 features identify psoriasiform dermatitis


By Michael Woodhead

7 Aug 2020

Children with the atypical paediatric psoriasis condition known as ‘psoriasiform dermatitis’ can be identified using eight significant features, Australian dermatologist have shown.

And children who have at least four of the eight key features of psoriasiform dermatitis will respond to psoriasis-specific treatments, according to a study by Dr Gayle Fischer and colleagues at the Department of Dermatology, Royal North Shore Hospital, Sydney.

Writing in Clinical and Experimental Dermatology, the clinicians say they aimed to identify the key features of patients they saw who do not display features accepted to be typical of classic paediatric psoriasis, nor of atopic dermatitis.

“These patients often share clinical and historical features that are found but not classically described in patients with paediatric psoriasis. Additionally, they often have a prolonged history of failure with appropriate atopic dermatitis-specific therapy,” they write.

In their study they compared 109 patients with classic paediatric psoriasis (well-demarcated psoriatic plaques, guttate disease, palmoplantar disease, nail pits, napkin psoriasis or pustular psoriasis) with a control group with  typical atopic dermatitis  (n = 49).

They found there was overlap between the two groups of up to 33%, and this allowed them to draw up a list of eight features that had a highly significant difference between groups:

  • Cradle cap
  • Nappy rash
  • Poststreptococcal or viral exacerbation
  • Exacerbation with weather change
  • Lack of pruritic insomnia
  • First degree relative with psoriasis
  • Scalp scale
  • Dorsal lichenification or papules of elbows and knees.

Other significant features were periauricular scale and erythema, acral fingertip eruptions, genital rashes and exacerbation with stress.

The two groups could be clearly separated at a score of 3 out of 8. And children with  four or more of these ‘psoriasiform dermatitis’ features responded well to treatments for psoriasis, such as combination calcipotriol/betamethasone dipropionate (Daivobet) and narrowband ultraviolet B (NB-UVB).

The overall response to treatment was good with a mean reduction of PASI by 85% at six weeks.

The study investigators said the term ‘psoriasiform dermatitis’ had not previously been formally defined, and the findings suggested there is a group of children on the spectrum of psoriasis between atopic dermatitis and typical paediatric psoriasis.

“We propose that these patients, who can be identified by the finding of ≥ 4 features commonly found in paediatric psoriasis, should be classified as having ‘paediatric psoriasiform dermatitis’,” they said.

“Identification of this group of patients, who although not having the typical clinical features of psoriasis, respond well to psoriasis-specific treatment, may assist treatment decisions for these patients,” they concluded.

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