What is psoriasis?

To put it in lay man terms, psoriasis is a chronic skin disease that is caused by the skin cells multiplying faster than they should. The normal life cycle of skin cells is approximately 28 days, i.e. it takes 28 days for the skin cells to grow out, die and fall off. (Yes we shed our skin and hair, just like any other animal. Obviously the process is quite dramatic in animals like snakes. But ours is a slower process). This process is accelerated to just 4-5 days, in areas of skin affected by psoriasis. Thus, the skin does not have enough time to be shed and accumulates as thick layers of dead skin. This is what causes the thick scales in psoriasis.

What causes psoriasis?
Psoriasis is believed to be genetically acquired, i.e. is due to a defect in the genes that regulate the multiplication of skin cells. However, a gene defect alone is not enough and there are believed to be a number of environmental triggers that are needed to ‘uncover’ the genetic defect.

What are the triggers for psoriasis?/ What makes psoriasis worse?

There are a number of aggravating factors/ triggers for psoriasis. These include:

1. Injury: It is quite common for psoriasis to occur on areas of injury. This is called Koebner’s phenomenon and can be recognised readily in areas of trauma.
2. Allergies to creams/ contact dermatitis: This does not cause psoriasis but yes, any skin allergy/ inflammation can induce psoriasis in that area via Koebner’s phenomenon, as described earlier.
3. Infections:
   1. particularly streptococcal (a bacteria) sore throat
   2. Candidal infections (thrush) can aggravate some types (flexural psoriasis) of psoriasis
   3. Yeast infections like malassezia (pityrosporum), can aggravate scalp psoriasis and a type of psoriasis called sebopsoriasis
4. Medications (may play a role in some cases)
5. Stress
6. Excessive alcohol consumption
7. Smoking
8. Obesity
9. Hormones: may play a role in psoriasis, particularly as we know that psoriasis can change during pregnancy. But the relationship between hormones and psoriasis is no entirely clear.
10. UV light: generally this makes psoriasis better. But 10% of psoriasis sufferers have a condition called photosensitive psoriasis, which is worsened by light exposure.

Does diet affect psoriasis?

Well, we know that there is a higher incidence of obesity n patients with psoriasis. However whether it is because people with psoriasis eat more because they are stressed, or the other way around, is not known. But really diet has no proven effect on psoriasis. One can eat anything (though advisable to stick to a healthy diet).

What are the types of Psoriasis?

Psoriasis is divided into various types depending on:

• The way it looks/ severity:
  • Chronic plaque psoriasis: This is the classical type and affects the elbows, knees, scalp, spine, etc. in the form of thick, scaly plaques.
  • Guttate psoriasis: Usually occurs after streptococcal sore throat. Presents in the form of 1-3 cm sized round plaques, scattered like rain drops all over the body.
  • Pustular psoriasis: Slightly severe form of psoriasis that presents with pus filled spots. This needs immediate medical attention.
  • Erythrodermic psoriasis: The most serious form of psoriasis where the entire body is affected in the form of redness +- scaling.
  • Sebopsoriasis: A combination of yeast infection (seborrhoeic dermatitis) and psoriasis, which commonly affects the scalp, face and upper trunk. 

• Areas of the body it affects:
  • Palmoplantar psoriasis: palms and soles
  • Scalp Psoriasis
  • Nail Psoriasis
  • Flexural psoriasis: body folds

Is there a cure for psoriasis?

Unfortunately since psoriasis is a genetic disease, it cannot really be cured (yet). However with adequate treatment, it can certainly be controlled to a level where it does not affect the quality of your life to a significant degree.

What treatment options are available for psoriasis?

The treatment of psoriasis entirely depends on the type of psoriasis and its severity. There are a number of other factors also to consider including your age, associated medical problems, history of skin cancer, previous treatment history, current medications you are taking and more importantly how much the disease is affecting your quality of life. Generally, the more effective the treatments (particularly tablets and injections), the more will be the side effects. Therefore one has to strike a balance between the side effect profile of the medications and how much the psoriasis is affecting your quality of life. This is only possible via a detailed consultation with a skin specialist.

The following are the treatment options available for the treatment of psoriasis. I would suggest you visit the Dermnet NZ website (link at the bottom) for further details regarding each of these treatments:

Topical creams/ ointments/ lotions/ shampoos:

• Moisturisers: especially ones containing urea are very important to take away the dead skin and allow the other creams to penetrate.
• Calcipotriol Steroid creams and ointments of various strengths
• Salicylic acid containing creams
• Coal tar: quite a messy treatment, but rewarding if you can persevere.
• Anti-fungal/ anti-yeast preparations, particularly for sebopsoriasis and flexural psoriasis
• Topical calcineurin inhibitors
• Dithranol: quite a messy treatment, but rewarding if you can persevere.

Systemic agents: (tablets/ capsules/ injections)

• Phototherapy:
  • UVB
  • PUVA
  • UVA1
• Acitretin/ Isotretinoin
• Methotrexate
• Ciclosporin
• Hydroxyurea
• Mycophenolate
• Fumaric acid esters (FAE’s)
• Biologics
  • Etanercept
  • Adalumimab
  • Infliximab
  • Ustekinumab

Additional reading:

Here is a list of websites, if you need further detailed information:

• Dermnet NZ
• British Association of Dermatologists
• Emedicine