A review of current treatment options for scalp psoriasis, which affects half to three-quarters of all patients with plaque psoriasis.
Psoriasis is a common skin condition that affects millions of people in the United States. The scalp is the most commonly affected body part. Although there are many clinical studies that have evaluated the efficacy of medications for plaque psoriasis, there is a paucity of randomized, double-blinded, comparator studies specifically for the treatment of scalp psoriasis. Patient compliance has been and continues to be an important consideration when choosing an appropriate therapy for scalp psoriasis. Newer vehicle formulations for topical agents, in addition to the compound formulation of corticosteroids with vitamin D analogue, have been some of the more important developments in the treatment of scalp psoriasis. This review briefly addresses the above issues with a focus on current treatment options for scalp psoriasis.
Psoriasis is a chronic inflammatory skin disease that affects more than 2% of adults in the United States.1 Psoriasis may be localized to one area of the body or generalized, involving different parts of the body.2 Among patients with plaque psoriasis, 50% to 79% have scalp involvement. At least 25% of patients with plaque psoriasis initially present with lesions on the scalp.3 The high follicular density of the scalp provides a moist environment that reduces natural light exposure, which has been suggested as a possible reason for the susceptibility of the scalp to psoriatic lesions.4 The most common symptoms of scalp psoriasis are scaling and pruritus.5 In some cases, it may be difficult to differentiate between scalp psoriasis and seborrheic dermatitis, but the presence of psoriasis in other locations usually helps to make the diagnosis.2 Although scalp psoriasis alone involves a small percentage of the body, it can have a profoundly negative affect on a person’s quality of life and self-esteem.4 Therefore, the effective treatment of scalp psoriasis deserves special attention.
A grading system for scalp psoriasis has not been well defined in the literature.6 Some clinical trials use the Psoriasis Scalp Severity Index (PSSI), which is similar to the Psoriasis Area Severity Index (PASI) for generalized psoriasis.7 The scale for PSSI ranges from 0 (absent) to 4 (very severe) for each of the three categories of erythema, desquamation and thickness, which are rated separately. The individual scores are then added and multiplied by a number based on the area of the scalp that is covered by psoriasis.8 The final PSSI score can range from 0 to 72. Another more commonly used scale is the scalp-modified PASI (S-mPASI), which is very similar to the PSSI but the results are divided by 10 with results ranging from 0 to 7.2.9
Treating Scalp Psoriasis
Although there is no cure for scalp psoriasis, a variety of treatments exist, with topical agents being the most commonly used option.10 Active ingredients for the various topical agents include corticosteroids, vitamin D3 analogues, coal tar, keratolytics, dithranol and retinoids.11 It is well known that patients with scalp psoriasis are often dissatisfied with many of the existing therapeutic options, due in part to the cosmetic appearance of their hair after application.4 Additionally, most available topical treatment options are found to be ineffective and time-consuming, which also contributes to a high degree of non-compliance. In general, newly developed vehicles such as gels, foams and sprays, which do not leave a greasy residue and are easier to apply, appear to be preferred by patients over traditional ointments and creams.12,13 Medicated shampoos are also easier to use than traditional agents because they are effective without the need to remain on the skin for extended periods of time.14
Topical Corticosteroids
Corticosteroids are considered the first choice therapy among the various topical agents available to treat scalp psoriasis.15 Topical corticosteroids have both anti-inflammatory and anti-pruritic properties. These agents are available in many different strengths, ranging from class 1 (most potent) to class 7 (least potent).14 The response to corticosteroid treatment for scalp psoriasis is faster than the response to other available agents, but the possible side effects, such as atrophy, are more likely to occur after prolonged use.16 There are no studies in the literature to support the safe use of topical corticosteroids beyond 1 month of treatment for scalp psoriasis.2 The choice of vehicles for corticosteroid treatment of scalp psoriasis includes ointment, cream, solution, gel, foam, spray and shampoo.16
Foam vehicles are one of the newer choices for the treatment of scalp psoriasis. Compared to traditional ointments and creams, they are absorbed more rapidly and are easier to apply with minimal residue. Clobetasol propionate (CP) 0.05% is one of the most potent topical corticosteroid preparations commonly prescribed for patients with scalp psoriasis.16 In an open label study involving 12 patients with scalp psoriasis, 100% of patients had at least a 50% reduction in their PASI score for the scalp after CP foam 0.05% was applied twice daily for 4 weeks.17
The shampoo formulation of CP 0.05% is also one of the newer options for the effective treatment of scalp psoriasis. A clinical trial compared the safety and efficacy of CP 0.05% shampoo versus CP 0.05% gel in 26 patients who were randomized to receive either product once daily for a period of four weeks. No ocular adverse events were noted in either treatment group. However, CP 0.05% gel caused more skin atrophy than CP 0.05% shampoo. The CP 0.05% gel formulation also resulted in suppression of hypothalamic–pituitary axis (HPA) function in two out of 12 patients after the first week of treatment; none of the 14 patients treated with CP 0.05% shampoo exhibited HPA suppression.18
Additionally, the efficacy and safety of CP 0.05% spray for the treatment of scalp psoriasis are consistent with results from other trials looking at the treatment of psoriasis at other body sites.19-23 In one trial, 81 patients were randomized to receive either CP 0.05% spray or vehicle spray; treatment was applied to the scalp twice daily for up to 4 weeks. At the end of treatment, 35 out of 41 patients in the CP 0.05% spray group achieved a score of 0 or 1 on the global severity scale compared with 5 out of 40 patients in the vehicle spray group.24
Vitamin D3 Analogues
Vitamin D3 analogues inhibit epidermal growth, promote normal keratinocyte differentiation and have anti-inflammatory properties.11 Irritation is a common side effect that tends to decrease based on duration of use. Calcipotriol is a vitamin D3 analogue that has been shown to be effective in treating scalp psoriasis. In a 52-week, open-label study involving twice-daily application of either calcipotriol solution or calcipotriol cream, the mean total score for scalp psoriasis had improved by 58% after 28 weeks of treatment. Skin irritation was the most commonly reported adverse event with peak incidence at week 2. Overall, there were no significant changes in calcium homeostatsis during this study.25 Another study found that twice-daily application of calcipotriol solution for a 4-week period was rated as significantly better than placebo by both investigator and patient.26
Combination Vitamin D3 Analogue and Corticosteroid
The irritation associated with the topical use of calcipotriol noticeably diminishes when combined with topical corticosteroids. This unique vitamin D3 analogue/corticosteroid therapy also reduces the amount of corticosteroid needed to successfully treat scalp psoriasis, which decreases the incidence of skin atrophy.27 In a double-blind study, patients were randomized to receive once-daily treatment with calcipotriene 50 μg/g plus betamethasone 0.5 mg/g, betamethasone 0.5 mg/g, calcipotriene 50 μg/g or vehicle alone for scalp psoriasis. After 8 weeks, 71.2% of patients receiving the vitamin D analogue/corticosteroid formulation had zero or very little disease compared to betamethasone 0.5 mg/g (64.0%), calcipotriene 50 μg/g (38.6%) or vehicle alone (22.8%).28 In a 52-week, double-blind study, patients were randomized to receive either calcipotriol 50 μg/g plus betamethasone dipropionate 0.5 mg/g or calcipotriol 50 μg/g for once daily application. Scalp irritation was significantly reduced in patients treated with the vitamin D analogue/corticosteroid formulation compared to calcipotriol alone (11.9% vs. 21.6%; OR: 0.49, P < 0.001).29
Coal Tar
The mechanism underlying the efficacy of crude coal tar in the treatment of scalp psoriasis involves inhibition of epidermal growth and inflammation. Although coal tar is one of the less expensive and more traditional treatment options for scalp psoriasis, many patients dislike the cosmetic appearance, pungent odor and staining properties associated with its use.11 In an investigator-blinded study, 162 patients were randomized to receive either CP 0.05% shampoo or a tar 1% blend shampoo to apply once daily. After 4 weeks of treatment, patients using CP 0.05 shampoos had a 50% decrease in their Total Severity Score (TSS) compared to a 14.5% decrease in the group treated with tar shampoo. The TSS was calculated using the sum score after separately rating erythema, desquamation and plaque thickening on a 10-point scale.30 In an 8-week, open-label study, patients were randomized to receive either calcipotriene scalp solution with a tar-based shampoo or calcipotriol with a non-medicated shampoo. Although both groups’ scores for scalp psoriasis improved by more than 50%, no significant difference in efficacy was found between the two treatment groups.31
Dithranol
There are few clinical trials evaluating the efficacy of dithranol for the treatment of scalp psoriasis.32 Although the active ingredient dithranol has been available for more than 80 years, most patients dislike its staining properties.5
Keratolytics
There are also few clinical studies evaluating the efficacy of keratolytics like salicylic acid for the treatment of scalp psoriasis.27 In an open-label study, 10 patients treated their scalp psoriasis with 6% salicylic acid in an ammonium lactate foam vehicle. The mean scores for erythema, thickness and scaling were reduced significantly from 5.4 to 1.7 after 4 weeks of treatment. By the end of the study, 60% of patients were characterized as clear or almost clear, and no adverse events were reported.33 Based on these results, the evaluation of 6% salicylic acid (in an ammonium lactate foam vehicle) in combination with topical corticosteroids and/or vitamin D analogues is warranted, especially for patients whose psoriasis is characterized by a high degree of thickness and scale.34,35
Tazarotene
There is a lack of clinical studies evaluating the effectiveness of tazarotene specifically for scalp psoriasis. However, based on the efficacy of tazarotene in controlled studies for the treatment of plaque psoriasis on other areas of the body, tazarotene is an important option when considering secondary therapies for scalp psoriasis. Although the effectiveness of tazarotene in the treatment of plaque psoriasis is not as pronounced as topical corticosteroids, combination therapy is often considered to reduce the occurrence of skin atropy.15,36
Phototherapy and Systemic Agents
Other therapies for scalp psoriasis include phototherapy and systemic medications.15 Although phototherapy is an effective option for treating psoriasis in other areas on the body, the density of hair follicles on the scalp hinders the delivery of ultraviolet light.27 The 308 nm excimer laser (using a fiber-optic hand piece and a scalp delivery device) offers a promising alternative to topical therapies; one case report showed a 90% improvement in the modified PASI score after the patient received 22 treatments.37 In an open label study involving 14 patients with scalp psoriasis, an average reduction of 3.6 in the S-mPASI score was achieved after 12 weeks of UVB treatments three times a week using a fiber-optic comb.38 Clinical data regarding the safety and efficacy of most systemic therapies including biologics and non-biologics for the treatment of scalp psoriasis are lacking. However, based on the known efficacy of these systemic agents in plaque psoriasis, these medications should be considered when severe scalp psoriasis persists despite appropriate trials with topical therapies.15
Conclusion
Scalp psoriasis is a condition that remains difficult to treat.16 Traditional therapies such as coal tar and dithranol preparations are associated with poor compliance due to cosmetic considerations. Vehicle formulations such as ointments and creams are also hard to apply, leave a greasy residue and are time-consuming.12,13 Newer vehicle choices such as foams and sprays have had a positive impact on patient adherence.16,17,18 Topical corticosteroids still remain the first line choice for most clinicians in the treatment of scalp psoriasis. However, more long-term studies are needed to evaluate the safety of topical corticosteroids beyond 4 weeks of therapy.15 The combination of a vitamin D analogue with a corticosteroid was shown to be safe and effective during a 52-week treatment period, but affordability of this new combination therapy hinders patient access.29 Overall, there is a lack of randomized, double blind studies comparing different agents for the most effective, safe and cosmetically acceptable therapy for patients with scalp psoriasis.27
Dr. Haddican is with the Department of Dermatology at Mount Sinai School of Medicine in New York.
Dr. Goldenberg is Assistant Professor of Dermatology and Pathology and Medical Director of the Dermatology Faculty Practice at Mount Sinai School of Medicine in New York.
Disclosures: Dr. Haddican has no conflicts to disclose Dr. Goldenberg is a speaker for Abbott and Leo and an investigator for GSK and Leo.
A review of current treatment options for scalp psoriasis, which affects half to three-quarters of all patients with plaque psoriasis.
Psoriasis is a common skin condition that affects millions of people in the United States. The scalp is the most commonly affected body part. Although there are many clinical studies that have evaluated the efficacy of medications for plaque psoriasis, there is a paucity of randomized, double-blinded, comparator studies specifically for the treatment of scalp psoriasis. Patient compliance has been and continues to be an important consideration when choosing an appropriate therapy for scalp psoriasis. Newer vehicle formulations for topical agents, in addition to the compound formulation of corticosteroids with vitamin D analogue, have been some of the more important developments in the treatment of scalp psoriasis. This review briefly addresses the above issues with a focus on current treatment options for scalp psoriasis.
Psoriasis is a chronic inflammatory skin disease that affects more than 2% of adults in the United States.1 Psoriasis may be localized to one area of the body or generalized, involving different parts of the body.2 Among patients with plaque psoriasis, 50% to 79% have scalp involvement. At least 25% of patients with plaque psoriasis initially present with lesions on the scalp.3 The high follicular density of the scalp provides a moist environment that reduces natural light exposure, which has been suggested as a possible reason for the susceptibility of the scalp to psoriatic lesions.4 The most common symptoms of scalp psoriasis are scaling and pruritus.5 In some cases, it may be difficult to differentiate between scalp psoriasis and seborrheic dermatitis, but the presence of psoriasis in other locations usually helps to make the diagnosis.2 Although scalp psoriasis alone involves a small percentage of the body, it can have a profoundly negative affect on a person’s quality of life and self-esteem.4 Therefore, the effective treatment of scalp psoriasis deserves special attention.
A grading system for scalp psoriasis has not been well defined in the literature.6 Some clinical trials use the Psoriasis Scalp Severity Index (PSSI), which is similar to the Psoriasis Area Severity Index (PASI) for generalized psoriasis.7 The scale for PSSI ranges from 0 (absent) to 4 (very severe) for each of the three categories of erythema, desquamation and thickness, which are rated separately. The individual scores are then added and multiplied by a number based on the area of the scalp that is covered by psoriasis.8 The final PSSI score can range from 0 to 72. Another more commonly used scale is the scalp-modified PASI (S-mPASI), which is very similar to the PSSI but the results are divided by 10 with results ranging from 0 to 7.2.9
Treating Scalp Psoriasis
Although there is no cure for scalp psoriasis, a variety of treatments exist, with topical agents being the most commonly used option.10 Active ingredients for the various topical agents include corticosteroids, vitamin D3 analogues, coal tar, keratolytics, dithranol and retinoids.11 It is well known that patients with scalp psoriasis are often dissatisfied with many of the existing therapeutic options, due in part to the cosmetic appearance of their hair after application.4 Additionally, most available topical treatment options are found to be ineffective and time-consuming, which also contributes to a high degree of non-compliance. In general, newly developed vehicles such as gels, foams and sprays, which do not leave a greasy residue and are easier to apply, appear to be preferred by patients over traditional ointments and creams.12,13 Medicated shampoos are also easier to use than traditional agents because they are effective without the need to remain on the skin for extended periods of time.14
Topical Corticosteroids
Corticosteroids are considered the first choice therapy among the various topical agents available to treat scalp psoriasis.15 Topical corticosteroids have both anti-inflammatory and anti-pruritic properties. These agents are available in many different strengths, ranging from class 1 (most potent) to class 7 (least potent).14 The response to corticosteroid treatment for scalp psoriasis is faster than the response to other available agents, but the possible side effects, such as atrophy, are more likely to occur after prolonged use.16 There are no studies in the literature to support the safe use of topical corticosteroids beyond 1 month of treatment for scalp psoriasis.2 The choice of vehicles for corticosteroid treatment of scalp psoriasis includes ointment, cream, solution, gel, foam, spray and shampoo.16
Foam vehicles are one of the newer choices for the treatment of scalp psoriasis. Compared to traditional ointments and creams, they are absorbed more rapidly and are easier to apply with minimal residue. Clobetasol propionate (CP) 0.05% is one of the most potent topical corticosteroid preparations commonly prescribed for patients with scalp psoriasis.16 In an open label study involving 12 patients with scalp psoriasis, 100% of patients had at least a 50% reduction in their PASI score for the scalp after CP foam 0.05% was applied twice daily for 4 weeks.17
The shampoo formulation of CP 0.05% is also one of the newer options for the effective treatment of scalp psoriasis. A clinical trial compared the safety and efficacy of CP 0.05% shampoo versus CP 0.05% gel in 26 patients who were randomized to receive either product once daily for a period of four weeks. No ocular adverse events were noted in either treatment group. However, CP 0.05% gel caused more skin atrophy than CP 0.05% shampoo. The CP 0.05% gel formulation also resulted in suppression of hypothalamic–pituitary axis (HPA) function in two out of 12 patients after the first week of treatment; none of the 14 patients treated with CP 0.05% shampoo exhibited HPA suppression.18
Additionally, the efficacy and safety of CP 0.05% spray for the treatment of scalp psoriasis are consistent with results from other trials looking at the treatment of psoriasis at other body sites.19-23 In one trial, 81 patients were randomized to receive either CP 0.05% spray or vehicle spray; treatment was applied to the scalp twice daily for up to 4 weeks. At the end of treatment, 35 out of 41 patients in the CP 0.05% spray group achieved a score of 0 or 1 on the global severity scale compared with 5 out of 40 patients in the vehicle spray group.24
Vitamin D3 Analogues
Vitamin D3 analogues inhibit epidermal growth, promote normal keratinocyte differentiation and have anti-inflammatory properties.11 Irritation is a common side effect that tends to decrease based on duration of use. Calcipotriol is a vitamin D3 analogue that has been shown to be effective in treating scalp psoriasis. In a 52-week, open-label study involving twice-daily application of either calcipotriol solution or calcipotriol cream, the mean total score for scalp psoriasis had improved by 58% after 28 weeks of treatment. Skin irritation was the most commonly reported adverse event with peak incidence at week 2. Overall, there were no significant changes in calcium homeostatsis during this study.25 Another study found that twice-daily application of calcipotriol solution for a 4-week period was rated as significantly better than placebo by both investigator and patient.26
Combination Vitamin D3 Analogue and Corticosteroid
The irritation associated with the topical use of calcipotriol noticeably diminishes when combined with topical corticosteroids. This unique vitamin D3 analogue/corticosteroid therapy also reduces the amount of corticosteroid needed to successfully treat scalp psoriasis, which decreases the incidence of skin atrophy.27 In a double-blind study, patients were randomized to receive once-daily treatment with calcipotriene 50 μg/g plus betamethasone 0.5 mg/g, betamethasone 0.5 mg/g, calcipotriene 50 μg/g or vehicle alone for scalp psoriasis. After 8 weeks, 71.2% of patients receiving the vitamin D analogue/corticosteroid formulation had zero or very little disease compared to betamethasone 0.5 mg/g (64.0%), calcipotriene 50 μg/g (38.6%) or vehicle alone (22.8%).28 In a 52-week, double-blind study, patients were randomized to receive either calcipotriol 50 μg/g plus betamethasone dipropionate 0.5 mg/g or calcipotriol 50 μg/g for once daily application. Scalp irritation was significantly reduced in patients treated with the vitamin D analogue/corticosteroid formulation compared to calcipotriol alone (11.9% vs. 21.6%; OR: 0.49, P < 0.001).29
Coal Tar
The mechanism underlying the efficacy of crude coal tar in the treatment of scalp psoriasis involves inhibition of epidermal growth and inflammation. Although coal tar is one of the less expensive and more traditional treatment options for scalp psoriasis, many patients dislike the cosmetic appearance, pungent odor and staining properties associated with its use.11 In an investigator-blinded study, 162 patients were randomized to receive either CP 0.05% shampoo or a tar 1% blend shampoo to apply once daily. After 4 weeks of treatment, patients using CP 0.05 shampoos had a 50% decrease in their Total Severity Score (TSS) compared to a 14.5% decrease in the group treated with tar shampoo. The TSS was calculated using the sum score after separately rating erythema, desquamation and plaque thickening on a 10-point scale.30 In an 8-week, open-label study, patients were randomized to receive either calcipotriene scalp solution with a tar-based shampoo or calcipotriol with a non-medicated shampoo. Although both groups’ scores for scalp psoriasis improved by more than 50%, no significant difference in efficacy was found between the two treatment groups.31
Dithranol
There are few clinical trials evaluating the efficacy of dithranol for the treatment of scalp psoriasis.32 Although the active ingredient dithranol has been available for more than 80 years, most patients dislike its staining properties.5
Keratolytics
There are also few clinical studies evaluating the efficacy of keratolytics like salicylic acid for the treatment of scalp psoriasis.27 In an open-label study, 10 patients treated their scalp psoriasis with 6% salicylic acid in an ammonium lactate foam vehicle. The mean scores for erythema, thickness and scaling were reduced significantly from 5.4 to 1.7 after 4 weeks of treatment. By the end of the study, 60% of patients were characterized as clear or almost clear, and no adverse events were reported.33 Based on these results, the evaluation of 6% salicylic acid (in an ammonium lactate foam vehicle) in combination with topical corticosteroids and/or vitamin D analogues is warranted, especially for patients whose psoriasis is characterized by a high degree of thickness and scale.34,35
Tazarotene
There is a lack of clinical studies evaluating the effectiveness of tazarotene specifically for scalp psoriasis. However, based on the efficacy of tazarotene in controlled studies for the treatment of plaque psoriasis on other areas of the body, tazarotene is an important option when considering secondary therapies for scalp psoriasis. Although the effectiveness of tazarotene in the treatment of plaque psoriasis is not as pronounced as topical corticosteroids, combination therapy is often considered to reduce the occurrence of skin atropy.15,36
Phototherapy and Systemic Agents
Other therapies for scalp psoriasis include phototherapy and systemic medications.15 Although phototherapy is an effective option for treating psoriasis in other areas on the body, the density of hair follicles on the scalp hinders the delivery of ultraviolet light.27 The 308 nm excimer laser (using a fiber-optic hand piece and a scalp delivery device) offers a promising alternative to topical therapies; one case report showed a 90% improvement in the modified PASI score after the patient received 22 treatments.37 In an open label study involving 14 patients with scalp psoriasis, an average reduction of 3.6 in the S-mPASI score was achieved after 12 weeks of UVB treatments three times a week using a fiber-optic comb.38 Clinical data regarding the safety and efficacy of most systemic therapies including biologics and non-biologics for the treatment of scalp psoriasis are lacking. However, based on the known efficacy of these systemic agents in plaque psoriasis, these medications should be considered when severe scalp psoriasis persists despite appropriate trials with topical therapies.15
Conclusion
Scalp psoriasis is a condition that remains difficult to treat.16 Traditional therapies such as coal tar and dithranol preparations are associated with poor compliance due to cosmetic considerations. Vehicle formulations such as ointments and creams are also hard to apply, leave a greasy residue and are time-consuming.12,13 Newer vehicle choices such as foams and sprays have had a positive impact on patient adherence.16,17,18 Topical corticosteroids still remain the first line choice for most clinicians in the treatment of scalp psoriasis. However, more long-term studies are needed to evaluate the safety of topical corticosteroids beyond 4 weeks of therapy.15 The combination of a vitamin D analogue with a corticosteroid was shown to be safe and effective during a 52-week treatment period, but affordability of this new combination therapy hinders patient access.29 Overall, there is a lack of randomized, double blind studies comparing different agents for the most effective, safe and cosmetically acceptable therapy for patients with scalp psoriasis.27
Dr. Haddican is with the Department of Dermatology at Mount Sinai School of Medicine in New York.
Dr. Goldenberg is Assistant Professor of Dermatology and Pathology and Medical Director of the Dermatology Faculty Practice at Mount Sinai School of Medicine in New York.
Disclosures: Dr. Haddican has no conflicts to disclose Dr. Goldenberg is a speaker for Abbott and Leo and an investigator for GSK and Leo.
A review of current treatment options for scalp psoriasis, which affects half to three-quarters of all patients with plaque psoriasis.
Psoriasis is a common skin condition that affects millions of people in the United States. The scalp is the most commonly affected body part. Although there are many clinical studies that have evaluated the efficacy of medications for plaque psoriasis, there is a paucity of randomized, double-blinded, comparator studies specifically for the treatment of scalp psoriasis. Patient compliance has been and continues to be an important consideration when choosing an appropriate therapy for scalp psoriasis. Newer vehicle formulations for topical agents, in addition to the compound formulation of corticosteroids with vitamin D analogue, have been some of the more important developments in the treatment of scalp psoriasis. This review briefly addresses the above issues with a focus on current treatment options for scalp psoriasis.
Psoriasis is a chronic inflammatory skin disease that affects more than 2% of adults in the United States.1 Psoriasis may be localized to one area of the body or generalized, involving different parts of the body.2 Among patients with plaque psoriasis, 50% to 79% have scalp involvement. At least 25% of patients with plaque psoriasis initially present with lesions on the scalp.3 The high follicular density of the scalp provides a moist environment that reduces natural light exposure, which has been suggested as a possible reason for the susceptibility of the scalp to psoriatic lesions.4 The most common symptoms of scalp psoriasis are scaling and pruritus.5 In some cases, it may be difficult to differentiate between scalp psoriasis and seborrheic dermatitis, but the presence of psoriasis in other locations usually helps to make the diagnosis.2 Although scalp psoriasis alone involves a small percentage of the body, it can have a profoundly negative affect on a person’s quality of life and self-esteem.4 Therefore, the effective treatment of scalp psoriasis deserves special attention.
A grading system for scalp psoriasis has not been well defined in the literature.6 Some clinical trials use the Psoriasis Scalp Severity Index (PSSI), which is similar to the Psoriasis Area Severity Index (PASI) for generalized psoriasis.7 The scale for PSSI ranges from 0 (absent) to 4 (very severe) for each of the three categories of erythema, desquamation and thickness, which are rated separately. The individual scores are then added and multiplied by a number based on the area of the scalp that is covered by psoriasis.8 The final PSSI score can range from 0 to 72. Another more commonly used scale is the scalp-modified PASI (S-mPASI), which is very similar to the PSSI but the results are divided by 10 with results ranging from 0 to 7.2.9
Treating Scalp Psoriasis
Although there is no cure for scalp psoriasis, a variety of treatments exist, with topical agents being the most commonly used option.10 Active ingredients for the various topical agents include corticosteroids, vitamin D3 analogues, coal tar, keratolytics, dithranol and retinoids.11 It is well known that patients with scalp psoriasis are often dissatisfied with many of the existing therapeutic options, due in part to the cosmetic appearance of their hair after application.4 Additionally, most available topical treatment options are found to be ineffective and time-consuming, which also contributes to a high degree of non-compliance. In general, newly developed vehicles such as gels, foams and sprays, which do not leave a greasy residue and are easier to apply, appear to be preferred by patients over traditional ointments and creams.12,13 Medicated shampoos are also easier to use than traditional agents because they are effective without the need to remain on the skin for extended periods of time.14
Topical Corticosteroids
Corticosteroids are considered the first choice therapy among the various topical agents available to treat scalp psoriasis.15 Topical corticosteroids have both anti-inflammatory and anti-pruritic properties. These agents are available in many different strengths, ranging from class 1 (most potent) to class 7 (least potent).14 The response to corticosteroid treatment for scalp psoriasis is faster than the response to other available agents, but the possible side effects, such as atrophy, are more likely to occur after prolonged use.16 There are no studies in the literature to support the safe use of topical corticosteroids beyond 1 month of treatment for scalp psoriasis.2 The choice of vehicles for corticosteroid treatment of scalp psoriasis includes ointment, cream, solution, gel, foam, spray and shampoo.16
Foam vehicles are one of the newer choices for the treatment of scalp psoriasis. Compared to traditional ointments and creams, they are absorbed more rapidly and are easier to apply with minimal residue. Clobetasol propionate (CP) 0.05% is one of the most potent topical corticosteroid preparations commonly prescribed for patients with scalp psoriasis.16 In an open label study involving 12 patients with scalp psoriasis, 100% of patients had at least a 50% reduction in their PASI score for the scalp after CP foam 0.05% was applied twice daily for 4 weeks.17
The shampoo formulation of CP 0.05% is also one of the newer options for the effective treatment of scalp psoriasis. A clinical trial compared the safety and efficacy of CP 0.05% shampoo versus CP 0.05% gel in 26 patients who were randomized to receive either product once daily for a period of four weeks. No ocular adverse events were noted in either treatment group. However, CP 0.05% gel caused more skin atrophy than CP 0.05% shampoo. The CP 0.05% gel formulation also resulted in suppression of hypothalamic–pituitary axis (HPA) function in two out of 12 patients after the first week of treatment; none of the 14 patients treated with CP 0.05% shampoo exhibited HPA suppression.18
Additionally, the efficacy and safety of CP 0.05% spray for the treatment of scalp psoriasis are consistent with results from other trials looking at the treatment of psoriasis at other body sites.19-23 In one trial, 81 patients were randomized to receive either CP 0.05% spray or vehicle spray; treatment was applied to the scalp twice daily for up to 4 weeks. At the end of treatment, 35 out of 41 patients in the CP 0.05% spray group achieved a score of 0 or 1 on the global severity scale compared with 5 out of 40 patients in the vehicle spray group.24
Vitamin D3 Analogues
Vitamin D3 analogues inhibit epidermal growth, promote normal keratinocyte differentiation and have anti-inflammatory properties.11 Irritation is a common side effect that tends to decrease based on duration of use. Calcipotriol is a vitamin D3 analogue that has been shown to be effective in treating scalp psoriasis. In a 52-week, open-label study involving twice-daily application of either calcipotriol solution or calcipotriol cream, the mean total score for scalp psoriasis had improved by 58% after 28 weeks of treatment. Skin irritation was the most commonly reported adverse event with peak incidence at week 2. Overall, there were no significant changes in calcium homeostatsis during this study.25 Another study found that twice-daily application of calcipotriol solution for a 4-week period was rated as significantly better than placebo by both investigator and patient.26
Combination Vitamin D3 Analogue and Corticosteroid
The irritation associated with the topical use of calcipotriol noticeably diminishes when combined with topical corticosteroids. This unique vitamin D3 analogue/corticosteroid therapy also reduces the amount of corticosteroid needed to successfully treat scalp psoriasis, which decreases the incidence of skin atrophy.27 In a double-blind study, patients were randomized to receive once-daily treatment with calcipotriene 50 μg/g plus betamethasone 0.5 mg/g, betamethasone 0.5 mg/g, calcipotriene 50 μg/g or vehicle alone for scalp psoriasis. After 8 weeks, 71.2% of patients receiving the vitamin D analogue/corticosteroid formulation had zero or very little disease compared to betamethasone 0.5 mg/g (64.0%), calcipotriene 50 μg/g (38.6%) or vehicle alone (22.8%).28 In a 52-week, double-blind study, patients were randomized to receive either calcipotriol 50 μg/g plus betamethasone dipropionate 0.5 mg/g or calcipotriol 50 μg/g for once daily application. Scalp irritation was significantly reduced in patients treated with the vitamin D analogue/corticosteroid formulation compared to calcipotriol alone (11.9% vs. 21.6%; OR: 0.49, P < 0.001).29
Coal Tar
The mechanism underlying the efficacy of crude coal tar in the treatment of scalp psoriasis involves inhibition of epidermal growth and inflammation. Although coal tar is one of the less expensive and more traditional treatment options for scalp psoriasis, many patients dislike the cosmetic appearance, pungent odor and staining properties associated with its use.11 In an investigator-blinded study, 162 patients were randomized to receive either CP 0.05% shampoo or a tar 1% blend shampoo to apply once daily. After 4 weeks of treatment, patients using CP 0.05 shampoos had a 50% decrease in their Total Severity Score (TSS) compared to a 14.5% decrease in the group treated with tar shampoo. The TSS was calculated using the sum score after separately rating erythema, desquamation and plaque thickening on a 10-point scale.30 In an 8-week, open-label study, patients were randomized to receive either calcipotriene scalp solution with a tar-based shampoo or calcipotriol with a non-medicated shampoo. Although both groups’ scores for scalp psoriasis improved by more than 50%, no significant difference in efficacy was found between the two treatment groups.31
Dithranol
There are few clinical trials evaluating the efficacy of dithranol for the treatment of scalp psoriasis.32 Although the active ingredient dithranol has been available for more than 80 years, most patients dislike its staining properties.5
Keratolytics
There are also few clinical studies evaluating the efficacy of keratolytics like salicylic acid for the treatment of scalp psoriasis.27 In an open-label study, 10 patients treated their scalp psoriasis with 6% salicylic acid in an ammonium lactate foam vehicle. The mean scores for erythema, thickness and scaling were reduced significantly from 5.4 to 1.7 after 4 weeks of treatment. By the end of the study, 60% of patients were characterized as clear or almost clear, and no adverse events were reported.33 Based on these results, the evaluation of 6% salicylic acid (in an ammonium lactate foam vehicle) in combination with topical corticosteroids and/or vitamin D analogues is warranted, especially for patients whose psoriasis is characterized by a high degree of thickness and scale.34,35
Tazarotene
There is a lack of clinical studies evaluating the effectiveness of tazarotene specifically for scalp psoriasis. However, based on the efficacy of tazarotene in controlled studies for the treatment of plaque psoriasis on other areas of the body, tazarotene is an important option when considering secondary therapies for scalp psoriasis. Although the effectiveness of tazarotene in the treatment of plaque psoriasis is not as pronounced as topical corticosteroids, combination therapy is often considered to reduce the occurrence of skin atropy.15,36
Phototherapy and Systemic Agents
Other therapies for scalp psoriasis include phototherapy and systemic medications.15 Although phototherapy is an effective option for treating psoriasis in other areas on the body, the density of hair follicles on the scalp hinders the delivery of ultraviolet light.27 The 308 nm excimer laser (using a fiber-optic hand piece and a scalp delivery device) offers a promising alternative to topical therapies; one case report showed a 90% improvement in the modified PASI score after the patient received 22 treatments.37 In an open label study involving 14 patients with scalp psoriasis, an average reduction of 3.6 in the S-mPASI score was achieved after 12 weeks of UVB treatments three times a week using a fiber-optic comb.38 Clinical data regarding the safety and efficacy of most systemic therapies including biologics and non-biologics for the treatment of scalp psoriasis are lacking. However, based on the known efficacy of these systemic agents in plaque psoriasis, these medications should be considered when severe scalp psoriasis persists despite appropriate trials with topical therapies.15
Conclusion
Scalp psoriasis is a condition that remains difficult to treat.16 Traditional therapies such as coal tar and dithranol preparations are associated with poor compliance due to cosmetic considerations. Vehicle formulations such as ointments and creams are also hard to apply, leave a greasy residue and are time-consuming.12,13 Newer vehicle choices such as foams and sprays have had a positive impact on patient adherence.16,17,18 Topical corticosteroids still remain the first line choice for most clinicians in the treatment of scalp psoriasis. However, more long-term studies are needed to evaluate the safety of topical corticosteroids beyond 4 weeks of therapy.15 The combination of a vitamin D analogue with a corticosteroid was shown to be safe and effective during a 52-week treatment period, but affordability of this new combination therapy hinders patient access.29 Overall, there is a lack of randomized, double blind studies comparing different agents for the most effective, safe and cosmetically acceptable therapy for patients with scalp psoriasis.27
Dr. Haddican is with the Department of Dermatology at Mount Sinai School of Medicine in New York.
Dr. Goldenberg is Assistant Professor of Dermatology and Pathology and Medical Director of the Dermatology Faculty Practice at Mount Sinai School of Medicine in New York.
Disclosures: Dr. Haddican has no conflicts to disclose Dr. Goldenberg is a speaker for Abbott and Leo and an investigator for GSK and Leo.
