What is seborrheic dermatitis?

Seborrheic Dermatitis

Seborrheic dermatitis is a common chronic inflammatory skin condition characterized by greasy yellowish scaling and erythema that primarily affects sebum-rich areas of the body, with pathogenesis linked to Malassezia yeast proliferation, sebaceous gland activity, and immune dysregulation. 1

Clinical Presentation

• Affected areas: Primarily affects sebum-rich regions including:

  • Scalp (dandruff in mild cases)
  • Face (particularly nasolabial folds, eyebrows, glabella)
  • Ears (including ear canal)
  • Chest
  • Upper back
  • Axillary folds
  • Inframammary folds
  • Inguinal folds 1

• Appearance:

  • Erythematous macules or plaques
  • Greasy yellowish scaling
  • Variable pruritus
  • In darker skin types: may present with hyper- or hypopigmentation with minimal scaling 2

Predisposing Factors

• More pronounced in patients with:
  • HIV infection
  • Parkinson's disease
  • Down syndrome 1
  • Immunocompromised states
  • Neurological disorders

Pathophysiology

Three key factors contribute to seborrheic dermatitis:

1. Lipid secretion by sebaceous glands
2. Malassezia species colonization (particularly M. ovale and M. furfur)
3. Immunologic dysregulation 2

Differential Diagnosis

Seborrheic dermatitis must be differentiated from:

• Acute otitis externa (when affecting ears)
• Atopic dermatitis (eczema)
• Psoriasis
• Contact dermatitis (irritant or allergic)
• Discoid lupus erythematosus
• Tinea infections 1

Treatment Approach

First-Line Treatments

1. Topical antifungal agents:

   • Ketoconazole 2% cream or shampoo (apply once daily for body lesions; twice daily for seborrheic dermatitis for four weeks) 3
   • Other options: ciclopirox, bifonazole, selenium sulfide 1

2. Anti-inflammatory agents (for short-term use):

   • Low-potency topical corticosteroids
   • Topical calcineurin inhibitors (tacrolimus, pimecrolimus) 1

Scalp Treatment

• Antifungal shampoos containing:
  • Ketoconazole
  • Selenium sulfide
  • Zinc pyrithione
  • Coal tar 4

Treatment Duration and Monitoring

• For facial and body seborrheic dermatitis: Apply ketoconazole cream twice daily for four weeks
• If no clinical improvement after the treatment period, the diagnosis should be reconsidered 3
• For scalp involvement: Long-term maintenance with antifungal shampoos 4

Maintenance and Prevention

• Regular use of antifungal products
• Gentle cleansing with pH-neutral formulations
• Avoid irritants and potential allergens
• Keep affected areas dry
• Apply hypoallergenic moisturizers once daily 1

Special Considerations

• Refractory cases: Consider evaluating for associated conditions like HIV or Parkinson's disease
• Prolonged treatment: Avoid extended use of potent topical corticosteroids, especially on the scalp, as they can potentially worsen hair loss 1
• Allergic reactions: Be aware that topical medications, particularly neomycin-containing products, can cause allergic contact dermatitis 1

Newer Treatment Options

Roflumilast foam has recently been approved as a topical treatment with potential to become a first-line option for seborrheic dermatitis, offering a well-tolerated alternative to traditional therapies 5.

Treatment Pitfalls to Avoid

• Using greasy topical products that can inhibit absorption of wound exudate and promote superinfection 6
• Applying topical products shortly before radiation treatment (for patients undergoing radiotherapy) 6
• Prolonged use of potent corticosteroids, which can lead to skin atrophy, telangiectasia, and potentially worsen hair loss 1
• Failure to recognize seborrheic dermatitis variants in different skin types, which may present with less scaling and variable erythema 2