Scalp Psoriasis

Plaques on the scalp are often thick and well demarcated with overlying whitish scale (Fig. 14.12), but can range from a flaky dandruff to thick, extensive, armor-like plaques.
Lesions are frequently hidden by hair or noted behind the ears.
Plaques often extend beyond the hairline and become more obvious when the hair is held back or when the retroauricular area is examined (Fig. 14.13).
Pruritus leads to scratching which may exacerbate the condition (Köbner reaction).
Often, the external ears and ear canals are involved (Fig. 14.14).
Plaques may be recalcitrant to treatment because hair blocks UV light as well as the application of topical psoriatic medications.

Differential Diagnosis

Seborrheic Dermatitis

Atopic/Eczematous Dermatitis

Management

Mild Cases

With minimal scaling and thin plaques (similar to what is seen in seborrheic dermatitis (see Chapter 13: Eczema and Related Disorders), mild scalp psoriasis can often be managed with antidandruff shampoos and a low to midpotency (class 4, 5, or 6) topical steroid, used as needed for itching.
Over-the-counter options include shampoos that contain tar (Zetar, T-Gel), selenium sulfide (Selsun Blue, Head & Shoulders), or salicylic acid (T-Sal).

Topical Steroids

A mid- or low-potency topical steroid can be used to clear thin plaques. Examples include Fluocinolone 0.01% solution or shampoo (Capex—class 4), and Verdeso foam (desonide 0.05%—class 6).
Gel, foam, or solution preparations reach the scalp more readily than do ointments or creams.

Topical Vitamin D Derivatives

Dovonex Scalp Solution or Sorilux Foam (both are calcipotriene 0.005%) can be applied twice daily for treatment, or once daily for maintenance or rotational therapy.

Severe Cases

In patients with thick scales and plaques, the scale must be removed before the plaques can be treated effectively. Scale removal is accomplished by applying either Keralyt gel or Salex cream or lotion (salicylic acid) one to three times per week. This regimen may be sufficient to keep scale under control, thus allowing penetration of a topical steroid.
After the scale is removed, a medium- to high-potency (class 2, 3, or 4) topical steroid is used. For example, fluocinonide 0.05% solution or gel (Lidex) or desoximetasone (Topicort) gel may be applied once or twice daily as needed; or under shower cap occlusion overnight or for 3 to 4 hours during the day.
If necessary, a superpotent (class 1) topical steroid such as clobetasol propionate 0.05% lotion, foam, shampoo, or gel can be used without occlusion. In recalcitrant situations, the superpotent topical steroid can be applied under occlusion once or twice per week.
Topical Vitamin D derivatives may be applied as maintenance or rotational therapy.
Injections of intralesional triamcinolone (3 to 5 mg/mL) in a limited amount (1 to 2 mL or less per treatment) every 4 to 8 weeks are used to target particularly recalcitrant or very itchy areas and may establish longer remissions.

SEE PATIENT HANDOUT, “Scalp Psoriasis: Scale Removal” IN THE COMPANION eBOOK EDITION.