Psoriasis: Diagnosis and Treatment

Psoriasis is an inflammatory skin condition affects 2% of the Caucasian populations at almost all age groups. There are two distinct types of this disease. Type I affects the younger age group around 20 years and type II affects older people peaking at age 50.

There are two pathologies are involved in psoriasis

1. Epidermal proliferation
   
2. T cell mediated inflammatory infiltration of dermis and epidermis
   

Known causes for psoriasis:

Hereditary: If both parents have psoriasis, the chance of their children to be affected is about 50%. About 30% of psoriasis patients has definite family history of affection.

Infection: Different infection of the skin may lead to psoriasis. Streptococci specially are major offender.

Drugs: Beta blockers, Lithium, Anti malarial are the known triggers for psoriasis.

How to diagnose psoriasis:

Psoriasis presents as symmetrical red plaques with well defined margins and silvery scales on it. They are mostly present on the outer (extensor) aspect of elbow, scalp, knees and sacral area. Non scaly lesions appears in the axillary folds, groins, umbilicus and below the breasts (sub mammary). Nails are also frequently affected with pitting, separation from the nail bed (onycholysis), thickening and subungual hyerkeratosis. In young individuals small plaques are also seen particularly when yhis is associated with streptococcal infection. Palms and soles are affected in pustular variety. Generalized psoriasis (erythrodermic and pustular) can cause severe systemic problems, which sometimes precipitated by rapid withdrawal of steroid drugs.

There are few signs of psoriasis.

Auspitz sign: when the scales are removed there will be pin point bleeding from the area.

Pepper pot nail pitting

Grease spot

In 7 % of the patients, joints can be involved in the process of psoriasis. These can be of five types:

• Asymmetrical Oligo mono arthritis
  
• Predominant DIP joints
  
• Rheumatoid-like Poly arthritis (Sero negative for Rheumatoid factor)
  
• Arthritis Mutilans (severe, destructive)
  
• Psoriatic Spondylitis
  

How to differentiate psoriasis with other skin conditions:

Psoriasis should be differentiated from the following skin disorders like eczema ( can be easily differentiated clinically) , mycosis fungoids ( these lesions has minimal scaling and they are asymmetrical as opposed to psoriasis. Biopsy is required to differentiate). Seborrhoeic dermatitis (These can coexist also)

Treatment of Psoriasis:

Patients must be counseled and educated properly. He must understand the condition is not curable, but control is possible by drugs. Trigger factors like infection or drugs, as mentioned earlier are to be removed. Topical drugs are used as a main form of treatment. Steroid creams, Calcipotriol, tacalcitol (vitamin D analogues) and different combinations are used to control the disease. Methotrexate helps in psoriatic arthropathy.

Drugs used in recalcitrant psoriasis

Tazarotene (a topical retinoid):

Prescribed in mild to moderate psoriasis affecting less than 10% of the skin surface. This is to be applied once daily.

Precautions:

Avoid in pregnancy.

Wash hands thoroughly after application.

Avoid contact with: Eyes, face, intertriginous areas, hair-covered scalp, eczematous or inflamed skin.

Avoid exposure to UV light/PUVA etc.

Don't use emollients or cosmetics within one hour of application of tazarotene.

Phototherapy:

Narrow-band UVB (TL-01): Weekly for 6 weeks

Avoid if there is history of photosensitivity. This treatment is most suitable for guttate/small plaque psoriasis.

PUVA: UVA + oral/topical psoralen:

This therapy is suitable for extensive large plaque disease (oral psoralen) and localized disease (topical psoralen)

The total dose has to be limited to 1000J/150 treatments. Over dosage may cause excessive skin ageing and increase the risk of skin cancer. can be combined with oral retinoids.

Oral Medications:

Severe psoriasis often needs oral medication. This should be prescribed and supervised by the expert in this field.

Methotrexate: 10mg - 25mg/week orally. Elderly patients get most help from this. This drug is better avoided in younger patients as there is a long-term risk of developing hepatic fibrosis.

Cyclosporin: 2.5mg - 5mg/kg/day orally. Side effects outweigh the advantage at times.

Acitretin: This is a oral retinoid and useful for moderate to severe disease. Being teratogenic this is not to be used in pregnancy. Drying of skin and mucosa is one of the side effects. Blood glucose, lipid and liver functions to be monitored continuously during the treatment.

Hydroxycarbamide (Hydroxyurea): 0.5 to 1.5g in 24 hours orally. Bone marrow suppression is the main side effect.

Parenteral cytokine inhibitors/monoclonal antibodies:

Etanercept (25mg SC, twice-weekly for less than 24wks) is now licensed to be used in adult plaque psoriasis, when other forms of treatment failed to give results. Already 3 randomized trial has been done with this therapy. It is a TNF ( Tumor necrosis factor) also help in psoriatic arthropathy ( joint diseases).

Usually this is a well tolerated drug but has some side effects like vomiting, GI bleeding, myocardial or cerebral ischaemia , respiratory distress, seizures etc so this drug if used, only to be used by experts. Another alternative to this drug is Infiximab.

This article is republished in India Study Channel