1.1.2.5 Seborrhoeic Dermatitis

Synonyms

Seborrhoeic otitis externa; malassezia folliculitis; seborrhoeic eczema; cradle cap (in infants).

Epidemiology

Very common in different ages. Infants first three month, later 4th life decade. All ethnic groups.

Definition

Chronic recurrent inflammatory dermatitis with yellow-white scaling on an erythematous background involving seborrhoeic areas.

Aetiology & Pathogenesis

Seborrhoea (oily skin), increased colonisation of seborrhoeic areas by commensal lipophilic yeast Malassezia spp. (formerly called Pityrosporum ovale). Often as HIV/AIDS related dermatosis. Often seen in Parkinson`s disease.

 

Signs & Symptoms

Scale; itch; irritation.

Localisation

Seborrhoeic areas: scalp, glabella, eyebrows, submental, retroauricular, mid-face, presternal, nasolabial folds and rarely intrascapular.

Classification

Seborrhoeic dermatitis of infants:

  • Usually in first 3 months.
  • Scalp, intertriginous areas.

 Seborrhoeic dermatitis of adults:

  • Seborrheic areas.
  • N.B: More severe manifestations with HIV.
  • Possible severe variant in the elderly with erythroderma and lymphadenopathy.
  • May overlap with psoriasis (Sebo-psoriasis).

Laboratory & other workups

Not necessary.

Dermatopathology

Hyper-and parakeratosis, crusts, serum and spongiosis, no Munro abscesses. 

Course

Worsens with stress, inflammatory and infectious diseases. UV light reported to both help and worsen. Unpredictable.

Complications

Overlap with psoriasis. Sometimes superinfection with S. aureus.  

Diagnosis

Oily skin, typical clinical features and distribution.

Differential diagnosis

Prevention & Therapy

Reduction of Malassezia colonisation with topical imidazoles, keratolytic agents, topical zinc pyrithione or topical zinc oil, especially in newborns. Short-term mild topical corticosteroids combined with clotrimazol.

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