Psoriasis

This is a chronic autoimmune condition characterised by well-demarcated, erythematous, scaly plaques.

The most common type in adults is the Plaque type, which is characterised by thick, erythematous plaques with silver scales, commonly seen on the extensors and scalp.

The most common type in children is the Guttate type, which is characterised by multiple small, raised papules across the trunk and limbs, which can become scaly over time. Over time, the papules turn into plaques. This is often triggered by step throat infection, stress or medications, and resolves spontaneously within 3-4 months.

The other 2 rare, more severe types are:

• Pustular – Pustules form under areas of erythematous skin and pt becomes systemically unwell

• Erythrodermic – Extensive erythematous inflamed areas covering most of skin. Skin comes away in large parches, leaving raw exposed areas.

In children, psoriasis is often triggered by strep throat infection.

Presentation

Specific signs:

• Residual pigmentation of skin after lesions resolve

• Auspitz sign – Small points of bleeding when plaques are scraped off

• Koebner phenomenon – Development of psoriatic lesions to areas that have been affected by trauma

• Nail changes - Pitting, thickening, discolouration, ridging, onycholysis

N.B. In children, psoriasis is often triggered by strep throat infection.

This condition is also associated with:

• Psoriatic arthritis – Occurs in 10-20% of patents

• Anxiety and Depression

  
  

Management

As psoriasis is typically characterised by inflammation and hyper-proliferation of keratinocytes (scales), the aim of management is to reduce this using things like steroids and vit D (reduce keratinocyte proliferation).

Medical options:

• Topical steroids

• Topical Vit D analogues (calcipotriol)

• Topical Dithranol

• Topical Calcineurin inhibitors (Tacrolimus)

• Phototherapy with narrow band UVB light