Endogenous eczema due to inflammatory response to Malassezia yeast characterized by scaling and poorly defined erythematous patches.
- Primarily affects sebum-rich areas (eg. scalp, face, upper chest, and back)
Aetiology
Clinical features
Characterized by the development of pruritic, erythematous patches with easily detachable, greasy large scales.
- Sites: Scalp, nasolabial folds. retroauricular region
- Scales: Greasy yellow scales
Clinical manifestations:
- Scalp: Cradle cap (infantile seborrhoeic dermatitis), dandruff
- Eyes, face: Seborrheic blepharitis (tends to affect the lateral sides of the nose + nasolabial folds + eyebrows + glabella)
- Chest: Annular SD
- Generalized: Erythrodermic SD
- Severe manifestations in:
- Parkinson disease
- HIV infection (sudden onset of lesions; lesions can be more widespread and recalcitrant with an associated discharge)
Seborrhoeic distribution:
- Scalp
- Face: Nasolabial folds, eyebrows & eyelashes
- Retroauricular area
- Presternal & interscapular area
- Major flexures: Axillae, groins, inframammary regions, umbilicus & nasal clefts
Complications
- Superadded bacterial infection
- Candidal infection
Diagnosis
Differential diagnosis
Dandruff:
Other differentials:
- Psoriasis:
- Prominent erythema
- Tendency for hair-line involvement
- More prominent silver scale
- Presence of psoriasis elsewhere (skin, nails, joints)
- Eczema:
- Atopic dermatitis: General skin examination & history
- Contact dermatitis: Distribution of eczema & history
- Tinea capitis:
- Microscopy, fungal culture of scalp scrapings
Management
Antifungals:
- Azoles (mainstay of antiseborrheic therapy):
- Inhibit ergosterol (important component of the fungal cell wall), via interference with the fungal cytochrome P-450 (CYP 450) system
- Topical ketoconazole, oral itraconazole, bifonazole ointment
- Oral Terbinafine (allylamine) & topical butenafine (benzylamine)
- Inhibit squalene epoxidase (important enzyme in the production of fungal cell membrane)
- Ciclopirox (hydroxypyridones)
- Fungicidal and fungistatic properties against a broad range of fungi as well as in vitro activity against gram-positive and gram-negative organisms + anti-inflammatory properties.
- Inhibits uptake of essential compounds via cell membrane, thereby altering cellular permeability
- Other non-prescription ingredients: Selenium, zinc, tea tree oil
Immunomodulators:
- Tacrolimus & Pimecrolimus
- Inhibit calcineurin and act primarily in an anti-inflammatory fashion by inhibiting cytokine production
- Tacrolimus also has potent fungicidal activity in vitro against Malassezia
- Other agents:
Other agents:
- Tar (antifungal (fungistatic) + anti-inflammatory + ↓ sebum production)
- Metronidazole
- Phototherapy
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