Seborrhoeic dermatitis may be associated with blepharitis and facial rash (Figure 1b). The rash may extend to involve the postauricular region with fissuring, as can otitis externa. Other areas, such as the axillae and groin, may show a glazed erythema with little scaling.
Seborrhoeic dermatitis is a chronic relapsing condition, and patients need to be reminded that treatment aims to control, not cure. In mild cases, regular use of an antidandruff shampoo is usually effective. Examples are shown in the Box. The shampoo should be massaged into the scalp and left for about five minutes before rinsing out. Washing the shampoo out too soon or not using it often enough are common causes of treatment failure. For more difficult cases, a topical antifungal preparation such as a ketoconazole cream may be used in addition to a shampoo. The cream is mixed with water and massaged into the scalp at night and washed out the next morning.
Patients with a greater degree of inflammation will benefit from the addition of a topical corticosteroid. Corticosteroid lotions are the easiest form to apply to hair-bearing areas and include methylprednisolone aceponate 0.1% and mometasone furoate 0.1% lotions. These can be used as needed.
When the scalp is thickly covered with scale, preparations such as extemporaneously compounded coal tar and keratolytics such as liquor picis carbonis (LPC) 3 to 6% with salicylic acid 3% in aqueous cream are beneficial.
Systemic antifungal agents such as itraconazole, terbinafine or fluconazole should be reserved for patients with severe or unresponsive disease. The quality of evidence examining the clinical efficacy of oral treatments in patients with seborrhoeic dermatitis is low, and there is no direct comparison between treatments.1
Psoriasis is a chronic, immune-mediated papulosquamous skin condition that is common in Australia, with an estimated prevalence of 2 to 6%. Psoriasis is a polygenic disorder that is influenced by a variety of environmental factors, such as trauma, medication and infection. The classic features – erythema, thickening and scale – are the result of abnormal keratinocyte proliferation and differentiation, vascular dilation and a population of inflammatory cells within the dermis and epidermis.
The scalp is involved in more than half of patients with psoriasis, and in some instances this may be the sole manifestation. Scalp psoriasis is characterised by well-demarcated erythematous plaques that have an adherent silvery scale. Lesions may advance beyond the hairline and extend to involve the retroauricular area (Figures 2a and b). In milder cases, scaling may be diffuse and nonspecific, and resemble pityriasis capitis. Psoriasis of the scalp seldom results in alopecia.
Psoriasis is a systemic disease process associated with a number of comorbidities. Psoriatic arthritis is the major systemic manifestation, affecting up to 30% of patients, and scalp psoriasis is a sign of increased risk of psoriatic arthritis. Patients have an increased risk of developing metabolic syndrome, cardiovascular disease, mental health issues, inflammatory bowel disease and certain malignancies, such as non-melanoma skin cancers, thus it is important to screen for and manage this vast range of comorbidities.2