Tea-time tutorial: Dandruff or scalp psoriasis?

Scalp psoriasis is a chronic autoimmune condition characterised by the rapid proliferation of skin cells and the formation of thick, red, scaly patches. These patches, or plaques, are often covered with a silvery-white build-up of dead skin cells. 

Dandruff or seborrheic dermatitis results from the overgrowth of a yeast called Malassezia, which is normally present on the skin. This overgrowth leads to an inflammatory response, causing excessive shedding of dead skin cells. Dandruff is characterised by white or yellowish flakes on the scalp and in the hair, often accompanied by itching and redness.

Key diagnostic differences

1. Appearance of scales
Scalp psoriasis: The scales in scalp psoriasis are typically thick, silvery and well-defined. They often form in patches and can extend beyond the hairline onto the forehead, neck and behind the ears.
Dandruff: Flakes are usually finer, greasy or dry, and white or yellowish in colour. They tend to be more diffuse and less well-defined than psoriasis scales.

2. Distribution and extent
Scalp psoriasis: Can affect the entire scalp and may extend to other parts of the body, such as the nails, elbows, knees and back, often in symmetrical patterns.
Dandruff: Primarily affects the scalp and is less likely to extend to other areas. Distribution does not follow a symmetrical pattern.

3. Associated symptoms
Scalp psoriasis: Itching is common but can vary in intensity. There may also be a burning sensation and soreness. 
Dandruff: Itching is the predominant symptom, often accompanied by a greasy scalp. There is generally no pain or burning sensation.

4. Recurrence
Scalp psoriasis: A chronic condition with a tendency for periodic flares. It is influenced by genetic, environmental and immunological factors.
Dandruff: Also a chronic condition but tends to have a more consistent presence, often worsened by stress, cold weather, and infrequent shampooing.

5. Response to treatment
Scalp psoriasis: Treatments include topical corticosteroids, vitamin D analogues and biologic agents. Phototherapy and systemic medications may be necessary for severe cases.
Dandruff: Antifungal shampoos containing ingredients like ketoconazole and selenium sulphide are effective in reducing Malassezia levels. Regular use of medicated shampoos can control symptoms effectively.

Diagnosis and management

Pharmacists should carefully assess the patient’s history and symptoms. Key questions to consider include:
• How long have the symptoms been present?
• Are there any other areas of the body affected?
• Is there a family history of psoriasis?
• What treatments have been tried and what was the response?

For scalp psoriasis, referral to a GP may be necessary for confirmation and advanced treatment. For dandruff, recommending appropriate OTC antifungal shampoos and advising on proper scalp hygiene can be effective.