About Psoriasis: The information is based on Textbook of Dermatology Edited by Bolognia JL, Jorrizo JL, Schaffer JV 3rd edition published by Elsevier

What is Psoriasis

Psoriasis is an autoimmune disease that causes raised, red, scaly patches to appear on the skin

Prevalence:

Affects2% of the world population.

Higher incidence in temperate climate

Can appear at any age

In 75% of patients occurs before the age of 40 years.

Classification:

Type 1 Psoriasis: Early age onset (in 20’s), positive family history of psoriasis, with an expression of HLA-Cw6

Type 2 Psoriasis: Late age onset (in 50’s), No family history and lack of HLA-Cw6.

How does it Progress??

It is characterized by periods of activity, stability and remission (disease free period) meaning the disease first spreads, may remain stable for a while or may disappear for sometime.

1. Family history: 35% to 90% of patients have positive family history. If both parents had psoriasis, the risk of their child developing the disorder was 41%, whereas if one parent was affected, the risk was 14%. If one sibling was affected, the risk was 6%.

2. Genetic Predisposition– Histocompatability antigens (HLA) are surface antigens of human cells. It is associated with several HLA antigens, mainly HLA-Cw6, which is associated with early onset of psoriasis.

3. Immune mechanisms: A strong pathogenic role of T cells (a type of white blood cells) is suggested. T cells are mainly CD8+, with an addition of CD4+.

4. Cytokines and Chemokines: Increased amounts of IFN-γ and IL-2 and decreased amounts of IL-10 are observed. It is believed that concerted actions of IL-17 and IL-22 lead to proliferation of keratinocytes and dermal inflammation. Circulating levels of IL-22 correlate with disease severity.

1. Chronic Plaque Disease: Most common variety-affecting majority of people. It appears as sharply defined, pinkish red (erythematous), plaques covered with silvery-white scales and symmetrically distributed. The degree of body surface area involvement can vary from limited to extensive.

2. Guttate Psoriasis: Lesions are small discrete papules and plaques. More commonly seen in children and adolescents and is frequently preceded by upper respiratory infection.

3. Palmoplantar psoriasis: psoriasis affecting the palms and soles only.

4. Psoriasis of Scalp: Well-defined reddish patches, usually extending beyond the hair margin and showing severe powdery thick scales.

5. Flexural psoriasis: Psoriasis confined to the body folds- underarms, behind the ears, infra-mammary area etc

6. Nail Psoriasis – very commonly affected. Fingernails are more common than toe nails. Pitting of nails is most common. Thickening of nail bed, loss of transparency and whitish, crumbled and poorly attached nail plate may be seen.

7. Erythroderma: is characterized by generalized redness and scaling involving the entire body with no islands of normal skin. Severe variant, may require hospitalization.

8. Pustular Psoriasis: It is characterized by white pustules (lesions of noninfectious pus) surrounded by red skin. The pus consists of white blood cells. It is not an infection, nor is it contagious. Pustular psoriasis can occur on any part of the body, but occurs most often on the hands or feet.

9. Psoriatic Arthritis – 5 to 30% of patients have associated arthritis. Risk factors of arthritis are – severe psoriasis, early onset of psoriasis, female gender, multiple joint involvement, genetic predisposition and early X ray changes in joints. Nail changes are often associated with psoriatic arthritis.

Treatment Options

Psoriasis can effectively be controlled, however, there is no known cure for it.

Counseling of patient and family members regarding its natural course and management is recommended. The principle of treatment should be a long-term approach with minimal adverse effects of medicines rather than dramatic short term fixes.

1. Vit D3 analogues (Calcipotriol/Calcitrol): It is effective in about 8 weeks of treatment. In practice, it is usually used in a combination with corticosteroids. Maximum recommended dose per week is 100 gms (Calcipotriol) and 200 gms (Vit D analogue). Other contraindications are kidney damage, allergy to Vit D3, pregnancy and lactation.

2. Corticosteroids:

First line therapy for mild to moderate psoriasis, alone or in combination. 80% of patients experience maximum improvement in 2 weeks.

Not used in presence of infections, atrophy of skin, and allergic reactions.

Used with caution in pregnancy and lactation.

For maintenance intermittent treatment over weekends is advised.

Tachyphylaxis (decrease in response after prolonged application) or rebound can happen. Weekend therapy or combination treatments can prevent this.

3. Anthralin: Second line of treatment as monotherapy in mild to moderate psoriasis or in combination. Not advised when disease is progressive or in pustular and erythrodermic psoriasis.

4. Topical retinoids: After 6 weeks of treatment 45% of patients experienced about 50% improvement using twice daily Vit D analogue Gel 0.05%3. Not used in unstable disease, erythrodermic psoriasis, allergy, pregnancy and lactation.

5. Others: When patches are thick and require better penetration of medicines Additional topical preparations can be used.

Salicylic Acid 5 to 10% can reduce thickness substantially. It can be used daily for small areas, but for widespread areas, 2 to 3 times per week is preferred to avoid systemic absorption and toxicity.

Coal Tar has a range of anti-inflammatory and anti pruritic action. Tar is not used in pregnant and lactating women.

Phototherapy:

First line treatment in moderate to severe psoriasis as monotherapy or in combination.

Not used in skin type 1, genetic disorders characterized by increased photosensitivity, or increased risk of skin cancer, high cumulative number of PUVA more than 200, treatment with Immunosuppressants, present or previous skin cancer.

1. Immunosuppressants: It was approved by US FDA for treatment of psoriasis in 1971. It is indicated in severe psoriasis (> 10 to 15% BSA), pustular and erythrodermic psoriasis, and not responding to other therapies. It is contraindicated with impaired kidney functions (creatinine clearance <60 ml/min), severe anemia, leukopenia and /or thrombocytopenia, active and/or recent hepatitis, excessive alcohol intake,

It was approved by US FDA for treatment of psoriasis in 1971. It is indicated in severe psoriasis (> 10 to 15% BSA), pustular and erythrodermic psoriasis, and not responding to other therapies. It is contraindicated with impaired kidney functions (creatinine clearance <60 ml/min), severe anemia, leukopenia and /or thrombocytopenia, active and/or recent hepatitis, excessive alcohol intake, 2. Cyclosporin: Indicated in severe psoriasis, and when conventional therapies are ineffective or cannot be used.

Indicated in severe psoriasis, and when conventional therapies are ineffective or cannot be used. 3. Systemic Retinoids: Retinoids is indicated in severe psoriasis that cannot be managed by topicals or phototherapy. Monotherapy is indicated for pustular or erythrodermic type, and combination for chronic plaque type.

Targeted immune modulators: beginning in 2000 they were introduced for severe psoriasis, and arthritis. Biologics, Biopharmaceutical, Adalimubab and secukinumab are available in market. They are mainly reserved for patients in whom all other treatment options are contraindicated or led to insufficient response.