Seborrheic Dermatitis

Introduction

Seborrheic dermatitis, also sometimes called seborrheic eczema, is a common, chronic skin disorder, that typically affects the face, scalp and trunk. Some define it as a subtype of eczema.

Its pathology is poorly understood, but it is thought to be a inflammation of the skin, often associated with the presence of the malassezia fungus. Many people carry this fungus asymptomatically, and it is also known to cause pityriasis versicolor.

• “Dandruff” is a type of seborrheic dermatitis

It can be divided into two types – that affects children, and that affecting adults (often young adults).

Pathology

Associated with the malassezia fungus, although this is also found in many asymptomatic individuals. It is thought that there is some sort of inflammatory reaction induced by the waste products produced by the fungus. Individual variation in natural skin barrier and skin lipids may account for the condition.

Infantile seborrheic dermatitis

Presentation

If only the scalp is affected, it is often referred to as “cradle cap”

• Typically babies <3 months old
• Usually resolves by 12 months
• Non-itchy
• Affects:
  • Scalp, cheeks, folds of neck, nappy area, folds of elbows and knees
• Produces a yellow coloured greasy scale
• Commonly associated with a bad nappy rash, which is often co-infected with candida

Differentiating from atopic dermatitis (eczema)

Eczema typically:

• Onset after 3 months
• Very itchy
• Very dry cracked skin (not an oily yellow scale)
• Typically nappy area is spared

Management

Basic measures

• Keep areas clean and dry
• Wash with warm water and then pat dry
• Keep skin exposed to air as much as possible
• Avoid use of soap (use cetaphil or similar emollient)
• Cradle cap
  • Wash off flakes with baby oil or soft paraffin, then wash away loose scales
• Nappy rash
  • Change soiled nappies frequently – minimise time of waste matter in contact with the skin
• Zinc based cream (e.g. sudocreme) applied on affected areas (barrier cream)

Medical management

• Scalp
  • 1-2% sulphur + 1-2% salicylic acid cream
    • Apply overnight
    • Shampoo off the next day with baby shampoo
    • Use 3x/week until resolved
  • 6% salicylic acid lotion
  • In older children
    • Ketoconazole 1-2% shampoo
    • Miconazole 2% shampoo
• Face, limbs and trunk
  • 2% salicylate + 2% sulphur cream
  • Ketoconazole 2% cream applied OD or BD
  • If severe – used steroids
    • 1% hydrocortisone BD for up to 7 days
    • 0.05% betamethasone – if very severe
• Nappy area
  • 1% hydrocortisone cream with 2% ketaconazole OR 1% clotrimazole cream
  • May be available as combination cream – e.g. hydrozole cream

Adult seborrheic dermatitis

Presentation

• Presents from teenage years onwards throughout adulthood
• Often recurrent
  • Worse with stress and fatigue
• Typically affects the head – particularly around hair-growing regions – scalp eyebrows, eyelids (blepharitis), and the nasolabial folds
• May also affect the torso, groin and the perianal area
• Red rash, with a yellow greasy scale
• Secondary candidiasis infection is common – especially in flexures

Management

• Scalp
  • Salicylic acid 2% + sulphur 2% in aqueous cream – applied overnight
    • Wash off the following day with selenium sulphide shampoo
    • Apply 3x per week
  • Ketaconazole shampoo 2% (anti-yeast shampoo)
    • Use immediately after the medicated shampoo described above
  • If non-responsive – try steroids – betamethasone dipropionate 0.5% lotion
    • Apply once daily at night for 7 nights
  • If STILL non-responsive, add coal tar 1% applied overnight, and wash off the next morning with anti-yeast shampoo
• Face and body
  • Wash frequently with a plain soap and water
  • Hydrocortisone 1% + clotrimazole 1% cream (“Hydrozole”) applied BD for 1-2 weeks
  • If unsuccessful, use a stronger steroid cream and an anti-fungal cream separately, e.g.g :
    • Methylprednisolone aceponate 1% cream – daily for up to two weeks
    • Ketaconazole cream 2% – applied daily for up to 2 weeks

References

• Seborrheic Dermatitis – Dermnet NZ
• Murtagh’s General Practice. 6th Ed. (2015) John Murtagh, Jill Rosenblatt
• Oxford Handbook of General Practice. 3rd Ed. (2010) Simon, C., Everitt, H., van Drop, F.
• Beers, MH., Porter RS., Jones, TV., Kaplan JL., Berkwits, M. The Merck Manual of Diagnosis and Therapy

Read more about our sources

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