The world of topical therapy

Lesions in scalp psoriasis affect frontal, parietal, temporal as well as occipital regions. The good visibility of the symptoms leads to additional suffering for those affected. In the area of topical treatment, corticosteroids, among others, have proven effective as monotherapy or in combination with vitamin D analogues.

As a common chronic inflammatory skin disease, psoriasis vulgaris affects about 170,000 Swiss – women somewhat less frequently than men. In many cases, initial manifestation occurs in the third decade of life, although any age can be affected. Family anamnesis reveals diseased ancestors in about 30% of patients. Up to 80% of patients present with scalp disease, sometimes in isolation. It is the most frequently affected body region at the onset as well as during the course of the disease [1]. The risk of developing psoriatic arthritis is reported to be increased fourfold in patients with head psoriasis [2]. Due to their visibility, scalp disorders in particular often have a stigmatizing effect on those affected and often lead to social withdrawal. Therapeutically, the patient and physician face great challenges.

Clinic

Clinically, sharply demarcated, erythemato-squamous plaques with silvery-white, medium to coarse lamellar scaling are found on the capillitium. In addition to single and disseminated foci, large confluent plaques may also be seen. Histologically, the classic changes of psoriasis are found. Possible stimuli for a development in this localization in particular could be the high hair density as a mechanically irritating or occlusive factor as well as skin damage, for example, by scratching (isomorphic irritation effect; “Köbner phenomenon”) with pronounced pruritus [3] (Fig. 1A, 1B).

In many cases, the skin lesions run parallel to the hairline and may cross the hairline, which is important for differential diagnosis (Fig. 2) . Up to 70% of patients complain of itching [3]. Associations with or transitions to seborrheic eczema (“seborrhiasis”) are found. Diffuse telogen effluvium of scalp hair is possible [4].

Problem of recording the severity of psoriasis capitis

While the Psoriasis Area and Severity Index (PASI) is a good tool for assessing changes on the entire integument, it is only possible to assess the situation on the scalp to a limited extent. Alternatively, the scalp-modified PASI, the Psoriasis Scalp Severity Index, or the quality-of-life-related Scalpdex can be used [3].

Topical vs. systemic therapy

Treatment of head psoriasis is primarily topical [3,5]. However, various factors, such as additional skin involvement on the trunk and extremities, joint infections, occupation or social environment, may influence the decision between topical therapy alone or a combination of topical and systemic therapy.

Therapeutically significant topicals (selection)
Salicylic acid: The substance has a keratolytic effect and is able to make the stratum corneum more permeable and to remove scales from the skin. This facilitates the access of other active ingredients on skin cells. Few studies with small patient numbers are available on this substance. A recommendation for use is derived primarily from decades of experience with salicylic acid. concentration between 3-10%, incorporated into a washable base are used in particular for dandruff solution [1]. Overview 1 shows the formulation for Salicyl-Carbowax 5% as an example. Restrictively, caution must be advised in the case of illness in children due to the risk of absorption for toxicologically questionable amounts (“salicylism”). Various reports of keratolysis to be achieved with other washable bases (e.g. Unguentum emulsificans aquosum) with and without foil occlusion have been reported [3].

Tar: The formerly frequent use of substances containing tar cannot be recommended at present due to the insufficient data available, the carcinogenic potential and the unpleasant odor.

Ammonium bituminosulfonate: Anti-inflammatory, antiseptic, antibacterial, antifungal, antipruritic, analgesic and keratolytic properties are cited for this active ingredient. A disadvantage for the user is a not infrequently perceivable “gas station”-like odor after application. In contrast to acne therapy, where for example the preparation ^Aknichthol® Lotion with the active ingredient sodium bituminosulfonate is brightly available in Switzerland, no finished product containing ammonium bituminosulfonate is currently approved in psoriasis therapy.

Cignolin (dithranol): Anti-inflammatory and anti-proliferative, this substance has been used successfully in psoriasis treatment for many years. Apoptosis of immune cells is discussed as the mechanism of action. While irritative reactions at the site of application are desirable (“the psoriasis burns in the fire of the cignolin”), accidental applications, e.g. to the eye region, can cause undesirable reactions. The discoloration of light-colored hair, fingernails, textiles, washbasins and other contact points is problematic. No finished medicinal products are currently approved in Switzerland.

There is a possibility of minute and long-term therapy with 0.05-3% concentration in washable base. An example of this is an extemporaneous preparation from the Zurich Cantonal Pharmacy (overview 2).

Glucocorticosteroids: These exert their anti-inflammatory effect by binding to specific cytosolic receptors. For topical administration in psoriasis capitis, different potent representatives are available as solution, foam or shampoo. Attention must be paid to possible side effects such as skin atrophy, rosacea, glaucoma or cataract. At sufficiently high potency (Class III and IV), they appear more potent than vitamin D analogues [8]. Table 1 contains examples of finished medicinal products containing glucocorticoids for use on the scalp.

Glucocorticoid/salicylic acid combination: this combination is said to soften the keratin of the skin surface through the salicylic acid effect, making the stratum corneum permeable and desquamating the epidermis so that the anti-inflammatory steroid can reach deeper tissue layers more easily. An example of this is a finished product with betamethasone and salicylic acid in an alcoholic base (Tab.2). In a study with 100 subjects published as early as 1983, it was shown that an alcoholic solution containing 0.64 mg betamethasone dipropionate and 20 mg salicylic acid supplement leads to a faster onset of action, desquamation, itch reduction, and anti-inflammation than the steroid monopreparation [9].

Vitamin D analogues: calcipotriol, tacalcitol and calcitriol are the best-studied representatives of this substance group. The mechanism of action is believed to be anti-inflammation and normalization of proliferation and differentiation of epidermal keratinocytes. The tacalcitol monopreparation Curatoderm® Lotion and Ointment and the calcitriol monopreparation ^Silkis® Ointment are currently available as finished products. In direct comparison, they appear less potent than steroids and combinations with steroids [8]. About 1% of the amount applied to the skin is absorbed. When administered in amounts greater than 100 g per week, blood calcium levels may be altered.

Combination glucocorticoid/vitamin D analog: fixed combination of calcipotriol and betamethasone for scalp treatment are available. They are superior to monotherapy with steroids [8]. Salicylic acid inactivates calcipotriol and must therefore not be used simultaneously ipsilocally. Table 3 provides an overview of this.

Ultraviolet comb: By means of this procedure, light treatment of lesions of the hairy head is aimed. Data regarding this therapeutic modality are sparse. Compared to a topical betamethasone valerate solution (n=22), a UV-B comb (^Dermalight® 80) still showed a comparable effect (n=22) with 5 applications per week for 3 weeks [10]. After 2 weeks, 7 of 22 subjects in the comb group were still in remission versus 3 of 22 in the bethametasone valerate group (p<0.05) [10]. Before a generally valid therapy recommendation can be given in this regard, larger case numbers in the half-side trial are also required here.

308-nm excimer laser: Treatment of scalp psoriasis shielded by dense terminal hair is considered challenging for the laser practitioner. On the other hand, skin lesions on the forehead, retroauricularly and on the nape of the neck, where the hairline is crossed, are easier to treat [11].

In a small hemiparesis study (n=13), 2 treatments per week resulted in improvement in up to 15 treatment weeks compared with no treatment. The difference in a modified PASI at the end of the study between the control group and the laser group was 4.0 (p>0.0001) [12].

Laser treatment was performed twice a week in 35 scalp psoriasis patients. After an average of 21 treatments (range 6-52 weeks), 49% of subjects had a >95% regression, and 45% had a 50-95% regression. Erythema and blistering occurred in all study participants, especially periauricular and nuchal [13]. Further investigations with larger numbers of cases, exact documentation of the initial and final findings and performance in a half-side test are required before a therapy recommendation can be made here.

Take-Home Messages

Psoriasis is able to alter frontal, parietal, temporal as well as occipital regions in a general or localized inflammatory way.
Affected persons not infrequently experience rejection due to the good perceptibility by third parties.
Topical therapies for psoriasis capitis are available in great variety. Corticosteroids as well as the combination of corticosteroid and vitamin D analogue prove to be the agents of choice.

Literature:

Wozel G, et al: Psoriasis of the hairy head. J Dtsch Dermatol Ges 2011; 9(1): 70-74.
Crowley J: Scalp psoriasis: an overview of the disease and available therapies. J Drugs Dermatol 2010; 9(8): 912-918.
Sticherling M: Psoriasis capitis and seborrheic eczema of the scalp. Dermatologist 2017; 68(6): 457-465.
George SM, Taylor MR, Farrant PB: Psoriatric alopecia. Clin Exp Dermatol 2015; 40(7): 717-721.
Wang TS, Tsai TF: Managing scalp psoriasis: an evidence-based review. Am J Clin Dermatol 2017; 18(1): 17-43.
Deplazes C, et al: Dermatological Magistral Prescriptions of Switzerland. Own publication, Winterthur 2010; p. 172.
Deplazes C, et al: Dermatological Magistral Prescriptions of Switzerland. Eigenverlag, Winterthur 2010; p. 187.
Schlager JG, et al: Topical treatments for scalp psoriasis: summary of a Cochrane Systematic Review. Br J Dermatol 2017; 176(3): 604-614.
Nolting S, Hagemeier HH. Therapy of erythematosquamous dermatoses. Fortschr Med 1983; 101(37): 1679-1683.
Dotterud LK, Braun R: UV-B-kam versus betametasonopplosning ved hodebunnspsoriasis. Tidsskr Nor Laegeforen 2000; 120(16): 1858-1859.
Schmieder A, Peitsch WK. Psoriasis in particular localizations. Dermatologist 2016; 67(6): 454-463.
Taylor CR, Racette AL: a 308-nm excimer laser for the treatment of scalp psoriasis. Lasers Surg Med 2004; 34(2): 136-140.
Morison WL, et al: Effective treatment of scalp psoriasis using the excimer (308 nm) laser. Photodermatol Photoimmunol Photomed 2006; 22(4): 181-183.