Psoriasis is a chronic inflammatory skin disease characterised by red plaques covered with silvery scales.

CAUSES OF PSORIASIS
The basic mechanism of psoriasis is excess skin formation. Normally skin cells can grow either as normal growth or as a healing wound with every skin cell having a life cycle of 28 days. However when the skin is wounded, a process known as regenerative maturation occurs, in which the skin cells are produced at a much faster rate with the aim of repairing the wound.

In psoriasis the skin cells go into perpetual regenerative maturation, i.e. inspite of no wound, the skin cells are formed at a very rapid rate but are not shed just as fast. The result: excessive skin cells which accumulate in form of elevated, scaly lesions, known as plaques. Modern research has shown that the aberration in skin cell formation occurs as a response to immunity cells attacking the skin, which is why psoriasis is now considered an autoimmune disorder.

TRIGGERING FACTORS
Psoriasis occurs in cycles of remission and relapses. Even without treatment, psoriasis can disappear almost up to 50-60% for a few months and then relapse to the same extent as before, which again will last for a few months. Psoriasis is a cyclical phenomenon.

FACTORS WHICH CAN LEAD TO A RELAPSE
• Emotional stress, especially sudden psychological trauma.
• Changes in weather conditions, especially onset of winters is known to cause a relapse in as many as 85% of patients of psoriasis.
Viral or bacterial, respiratory infections.

COMMON TYPES OF PSORIASIS
• Plaque psoriasis: This is the most common type of psoriasis, and its typical appearance has been described earlier.
• Pustular psoriasis: It is characterised by formation of large, pus filled blisters and in severe cases can even lead to grave danger.
• Erythodermic psoriasis: This is characterised by widespread reddening and scaling of skin.
• Guttate psoriasis: Drop-like lesions appear mainly on abdomen, limbs and scalp.
• Inverse psoriasis: Large, dry, smooth red plaques occur in folds of skin, near places like the genitals, under breasts or under armpits.

COMPLICATIONS CAUSED BY PSORIASIS
As such, there are no life threatening complications of psoriasis. Other than the skin, however, it can affect.
• Joints: This is a condition known as psoriatic arthritis, characterised by pain, swelling and inflammation of joints, most commonly the small joints like fingers, toes etc. This is believed to occur in 10-20% cases of psoriasis and is not related to the severity of the disease.
• Nails: Psoriasis can spread to the nails, causing distortion, thickness and even the appearance of multiple small pits on them.
• The mind: Even though psoriasis is not a fatal disorder, its effects on the psyche of a patient should not be disregarded. Medical researchers in USA used a parameter called Health Related Quality of Life (HRQL) to assess the degree of emotional suffering of a psoriatic patient. The results showed that the degree of emotional suffering was very similar to that of major medical disorders like cancer, arthritis, hypertension, heart disease, diabetes and depression. Thus, psoriasis can have a profound effect on the overall well being of a person.