Flakes of dead skin cells and an itchy scalp. These may sound like symptoms of dandruff, a flaky scalp condition. However, they may signal a more serious condition - psoriasis.

Psoriasis is an inflammatory skin condition characterised by red, scaly patches of skin.

The National Psoriasis Foundation in the United States explained that the cause of the condition is unknown, but the immune system and genetics are thought to play major roles in its development.

In psoriasis, the immune system is somehow activated, causing a series of events, including the acceleration of skin growth.

Usually, normal skin cells mature and shed in 28 to 30 days.

However, a psoriasis patient may find his skin cells maturing in just three to four days. Instead of falling off, the cells build up on the surface of the skin, forming lesions.

Stress, skin injuries and climate factors - say a cold, dry and wintery place - may worsen psoriasis.

The most common type of psoriasis that affects the scalp is plaque psoriasis. This appears as raised, red and scaly patches.

Some people with scalp psoriasis may be unaware that they have the condition.

For example, a patient with scalp psoriasis may think he has severe dandruff because some of the symptoms are similar, said Dr Derrick Aw, a consultant at the University Dermatology Clinic at National University Hospital.

Like dandruff, which may be caused by a fungal infection, people with scalp psoriasis may also have white or silvery flakes. However, unlike dandruff, these flakes are thicker. These patients usually also have itchy, red and scaly raised patches on their scalp, he said.

Scalp psoriasis is commonly treated through medicated hair washes, such as shampoos containing coal tar or salicylic acid, or topical drug applications.

However, treating it is a challenge, said Dr Aw.