Psoriasis is a common chronic inflammatory skin condition that may occur at any age and usually affects the skin of the elbow, knees, and scalp. It is non-contagious but is seen to run in families. There are periods of remission alternating with periods of exacerbation but a total cure is not possible. Psoriasis is typically seen as symmetrical, well-defined red patches with silvery scales on the outer aspects of the elbows, knees, and scalp. Nail changes may be seen as pitting, thickening, or separation from the nail bed. The joints may be involved in some cases.
Scalp psoriasis may be seen along with the generalized skin condition or it may occur without any other visible skin manifestation. It may be present in as many as 50% of people with psoriasis. While it is usually seen at the back of the head, psoriasis may also occur anywhere on the scalp as isolated patches of red areas covered by thick silvery scales, and may extend beyond the hairline. The scales tend to flake and may give the appearance of dandruff. The patchy scales or thick crust on the scalp may bleed when removed. These areas are often extremely itchy, which can be socially embarrassing, and may lead to temporary localized hair loss in very severe cases. Permanent balding does not usually occur.
Psoriasis of the Scalp (Pictures above and below from Dermatology Atlas : Courtesy Samuel Freire da Silva, M.D.)
Other Conditions Similar to Scalp Psoriasis
Scalp psoriasis may be differentiated from other itchy scalp conditions by a thorough physical examination. Psoriasis present in other parts of the body will be a pointer to the diagnosis. A skin biopsy can confirm the diagnosis.
The conditions that should be differentiated from scalp psoriasis are :
Seborrheic Dermatitis of the Scalp
This is typically seen as an itchy skin condition with a red, greasy, scaly skin which is usually covered with flaky white or yellow scales. Seborrhea tends to occur in parts of the body with high oil (sebum) production and when it affects the scalp, it is known as dandruff. The lesions are itchy and patchy scales or thick crusts are easily removed.
Patches are usually confined to the hairline and does not cause permanent hair loss. Seborrhea of the scalp in newborn may appear as “cradle cap”. Seborrheic dermatitis may be seen in other parts of the body, particularly on the face, chest, and back.
Seborrheic Dermatitis of the Scalp (Picture from Dermatology Atlas : Courtesy Samuel Freire da Silva, M.D.)
Seborrheic dermatitis, which is most often confused with psoriasis, may also co-exist. The condition is known as sebopsoriasis. There are more of yellowish scales than the typical silvery scales of psoriasis. Scalp localization is more of the seborrheic dermatitis type. It has a deeper red color, thicker scales, and more defined margins than seborrheic dermatitis.
Scalp Ringworm (Tinea Capitis)
Tinea capitis is a highly contagious fungal infection of the scalp. It usually presents as itchy, scaly, gray or reddish areas on the scalp. There may be painful areas on the scalp and round, bald patches on the scalp which may expand over time. The patches have small dots where the hair has broken off. It is more common in young children.
Scalp Ringworm (Picture from Dermatology Atlas : Courtesy Samuel Freire da Silva, M.D.)
This may cause purple or reddish-purple bumps on the skin with flat tops and uneven skin margins. There may be white scales or flakes on the lesions and it is often itchy. It usually affects the inner side of the wrists, forearms, and ankles but can also affect the scalp, nails, oral cavity, vagina, and anus.
Lichen planus of the scalp can cause permanent hair loss, as opposed to only temporary hair loss in a severe case of scalp psoriasis. Sometimes, tiny, red swellings may form around a cluster of hair follicles. There may be permanent bald patches. In some cases, there may not be any scaling or inflammation but bald areas of scarring may slowly develop.
Lichen Planus (Picture from Dermatology Atlas : Courtesy Samuel Freire da Silva, M.D.)
Thick yellow-white scales covering the scalp and adhering to the hair follicles. The scales are arranged in an overlapping manner, similar to tiles on a roof. The skin beneath the scales may look normal or slightly reddish.
It usually covers the scalp partially but may involve the whole scalp and there may be temporary hair loss. Permanent hair loss may occur if associated with infection.
Eczema presents as dry reddened skin with intense itching. There may be blisters and oozing lesions in some cases. It may involve any part of the body and scalp eczema is more likely to occur in young children.
Atopic dermatitis (Picture from Dermatology Atlas : Courtesy Samuel Freire da Silva, M.D.)
Complications of Scalp Psoriasis
- Temporary hair loss.
- Socially embarrassing and hence may lead to loss of self esteem and depression.
- Flaring up of psoriasis elsewhere in the body, such as psoriatic arthritis and pustular psoriasis.
- Secondary infection.
- Drugs used in treatment may have severe side effects.
Treatment of Scalp Psoriasis
Psoriasis can be particularly hard to treat. There is no permanent cure. Treatment may give some relief from symptoms and provide periods of remission.
Treatment can be of 3 types :
- Topical – skin applications.
- Phototherapy – light therapy.
- Medication – drugs.
Topical applications are the mainstay of treatment in most cases. In mild to moderate cases topical therapy alone may be administered or it may be combined with phototherapy. Drugs (oral or injection) are given only in severe, persistent cases or if psoriasis is present elsewhere in the body.
Topical therapy may be prescribed in the form of medicated shampoos, ointment, gel, or foam preparations, and oil-based preparations. These applications may contain one or more of the following substances :
- Vitamin D analogues
- Topical retinoids
- Calcineurin inhibitors
- Salicylic acid
- Coal tar
Ultraviolet (UV) rays may not reach the scalp if it is covered with thick hair. Parting the hair in rows or shaving the head may help. UV combs can deliver a higher intensity of UV rays.
Light therapy may include :
- Sunlight – exposure to UV rays in controlled amounts of natural sunlight.
- Ultraviolet B (UVB) phototherapy.
- Photochemotherapy (PUVA) – psoralen (a light-sensitizing drug) is taken prior to exposure to ultraviolet A light.
- Excimer laser
- Pulsed dye laser
Drugs may be given in oral or injection form only in case of severe psoriasis since these drugs can produce many undesirable side effects. These drugs may include :
- Immunomodulator drugs (biologics)