Scalp psoriasis

Psoriasis can be cause of a patient presenting with severe 'dandruff'.

Scalp psoriasis

• affects 75-90% of people with psoriasis (1)
  • usually presents as chronic plaque psoriasis affecting the scalp area
    
    
  • scalp psoriasis may affect the whole scalp or may present as individual plaques
    
    
  • plaques may be very thickened - this is particularly the case in occipital scalp psoriasis
    
    
  • there may be areas of non-scarring alopecia in scalp psoriasis
    • may occur if
      • pityriasis amiantacea - there is thick, adherent scale extending up the hair shaft
        • thick silvery or yellowish scales encircle the hair shafts and may bind down tufts of hair
        • click here for image of pityriasis amniantacea
        • scales may resemble asbestos, giving rise to the term amiantacea - the French word for asbestos is 'amiante' (2)
        • is a reaction pattern rather than a specific diagnosis
          • common conditions that may present with pityriasis amiantacea include:
            • scalp psoriasis
            • seborrhoeic dermatitis
            • atopic dermatitis
            • tinea capitis
            • head lice and lichen simplex should also be considered
          • when no underlying cause is found, the condition is often called idiopathic pityriasis amiantacea
          • may be complicated by secondary staphylococccal infection (impetiginisation), when the skin becomes sticky, oozy and crusted. Temporary or permanent hair loss (alopecia) may also occur (2)
            
            
      • erythrodermic psoriasis - in this severe form of psoriasis there may be associated alopecia
        
        
      • secondary to repeatedly scratching of the scalp (usually reversible)

If diagnosis is uncertain:

• pityraisis amiantacea - if the underlying skin condition is not clear, the entire skin should be examined to uncover the cause of pityriasis amiantacea. This enables targeted therapy against the specific disease and prevents long term complications such as permanent alopecia (3)
  • skin and hair samples for mycology; bacterial culture may be useful
  • skin biopsy is rarely necessary.

Management of scalp psoriasis (3) is outlined:

Scalp psoriasis requires slightly different regimes from psoriasis affecting the skin elsewhere

• this is due to hair, which makes the application of many topical products difficult and protects the scalp from the effects of ultraviolet light
• unfortunately, many scalp treatments for scalp psoriasis are messy and smelly
• most treatments will need to be used regularly for several weeks before a benefit is seen

Shampoo:

• for long-term management Tar based preparations eg Polytar (R) or Alphosyl (R) shampoo are useful when scale is present - massage into the scalp for five minutes to allow the shampoo to penetrate the scale and then wash out
• some patients are not keen on the smell of tar based preparations and may wish to try an alternative such as Dermax (R) shampoo

Topical applications: for flare-ups

• if the shampoo alone does not suffice add in a topical application.
  • treatment options include:
    • Dovobet (R) Gel Applicator which has the benefit of combining a topical steroid with a vitamin D analogue, and is proven to be superior when compared to using either agent alone
      • applicator will allow a precise amount of gel to be massaged on to affected areas on scalp while dry
      • Dovobet gel can sometimes leave the scalp feeling greasy and so it is recommended that the gel is applied in an evening and is washed out the following morning with shampoo that should be massaged in to the treated areas of the scalp before washing off with water
        
        
    • a ttopical steroid scalp preparation eg Betacap (R) scalp application
      • need to be applied to affected areas of the scalp when dry, and left on (ie the hair should be washed at the other end of the day). It is best to avoid alcohol based solutions, which are not as well tolerated
        
        
    • Etrivex (R) shampoo
      • needs to be massaged on to the scalp and left on for 20 minutes before washing out

Thick scale

• some patients present with thick scale and this needs to be removed before commencing the topical applications referred to above
  
  
• Sebco (R) scalp ointment is very effective at removing scale
  • massage in to affected areas of the scalp for five minutes and leave on for at least two hours, but preferably overnight (some patients cannot tolerate the treatment for more than a few hours)
  • Sebco should be washed out with Capasal (R) shampoo
  • the treatment is messy and so if left on overnight patients should use an old pillowcase or towel, alternatively the scalp can be occluded with a shower cap. Sebco may be need to be used for a few days until the scale diminishes, and then used PRN as the scale builds up
• Warn patients that hair loss may occur as the scale come away, but that this will recover (3)

Hair margins

• consider topical 1% Hydrocortisone or Eumovate (R) BD

Severe scalp psoriasis

• patients not responding adequately to treatment should for referred to a dermatologist for consideration of other treatments such as methotrexate or intralesional steroid injections, the latter is the less effective of the two

Notes:

• sebopsoriasis is an overlap between psoriasis and another common skin condition, seborrhoeic dermatitis. Sebopsoriasis tends to have less silvery scale than psoriasis and more yellowish, greasy scale (2)

Reference:

1. CKS. Psoriasis (Accessed 31/7/19)
2. DermNet NZ. Pityriasis amiantacea (Accessed 31/7/19)
3. Primary Care Dermatological Society. Scalp Psoriasis (Accessed 31/7/19)