Prevalence of Scalp Psoriasis
Scalp psoriasis is a common and difficult-to-treat manifestation of psoriasis.1,2 The prevalence of scalp psoriasis in patients with psoriasis is estimated to be 45% to 56%.3 Other studies have shown 80% to 90% of patients with psoriasis have scalp involvement at some point during the course of their disease.2,4-6
Scalp psoriasis typically presents as red thickened patches with silvery white scales that flake and may be mistaken for dandruff.7,8
The lesions may be limited to the hairline or may extend to the forehead, ears, and back of the neck.1,9 Patients often report intense itching, feelings of soreness, and burning.10,11 Patients with scalp psoriasis also are vulnerable to Koebner phenomenon because normal hair care along with scratching or picking at lesions can result in skin trauma and a cycle of exacerbating disease.11
Quality of Life Implications
Scalp involvement can dramatically affect a patient’s quality of life and often poses considerable therapeutic challenges for dermatologists.2,12,13 In one study, more than 70% of patients with scalp psoriasis reported difficulty with daily life.12 Patients frequently report feelings of shame, embarrassment, or self-consciousness about scalp psoriasis; many grow their hair long or wear hats to hide scalp lesions. Others report that flaking sometimes, often, or always affects their choice of clothing color.7,12
Alopecia is another common sequala in the setting of scalp psoriasis, though it is not well understood.14,15 First described by Shuster16 in 1972, psoriatic alopecia is associated with diminished hair density, follicular miniaturization, sebaceous gland atrophy, and an increased number of dystrophic bulbs in psoriatic plaques.14,17 Clinically, it presents as pink scaly plaques consistent with psoriasis with overlying alopecia. In most patients, hair loss is usually reversible following effective treatment of psoriasis; however, instances of psoriatic alopecia have been reported as cicatricial (permanent) hair loss and generalized telogen effluvium. Cicatricial alopecia is increasingly being linked with chronic relapsing episodes of psoriasis.14,15 Patients with psoriatic alopecia are known to have a higher proportion of telogen and catagen hairs.14,18 Moreover, patients with psoriasis have more dystrophic hairs in affected and unaffected skin despite no differences in skin when compared to unaffected patients.14
The patient described here had scalp psoriasis with increased and preserved hair density. The case suggests that while most patients with scalp psoriasis experience psoriatic alopecia of the lesional skin, some may unconventionally experience increased hair density, which is contradictory to propositions that the friction associated with the application of topical treatments results in breakage of telogen hairs.14,15
Although numerous treatment options for psoriasis are available, the scalp remains a difficult area to treat.1,14 Increased hair density can complicate antipsoriatic treatment by making the scalp inaccessible and topical therapies even more difficult to apply.14 The presence of hair also has been shown to strongly influence treatment adherence.1,8 Patients often discuss the greasy effect of medications in this area and difficulty removing products from the hair.1
Topical corticosteroids, with or without the addition of the vitamin D analogs calcipotriol or calcipotriene, remain the first-line treatment of mild scalp psoriasis. It is possible that the development of new formulations in recent years—foams, shampoos, and sprays—may improve adherence. Systemic treatment should be considered in severe or intractable cases.
Although hair loss is more common, scalp psoriasis also may present with increased hair density, which may make topical medications more difficult to apply and can affect treatment adherence. Topical corticosteroids, with or without the addition of the vitamin D analog calcipotriol, remain the first-line treatment of mild scalp psoriasis. Systemic therapy should be considered in severe or recalcitrant cases.