Seborrheic Dermatitis
Chronic relapsing dermatitis of sebum-rich areas associated with Malassezia overgrowth; manifests as cradle cap (infants) and dandruff (adults).
Also known as: seborrheic dermatitis, seborrhea, dandruff, cradle cap, seb derm
Overview
A common chronic inflammatory dermatosis affecting sebum-rich areas (scalp, eyebrows, nasolabial folds, ears, chest, intertriginous folds) characterized by greasy yellow scale and erythema.
Epidemiology
Bimodal age distribution: infants (cradle cap) 0-3 months, resolves by 1 year; adults peak 30-60 years. Male predominance in adults. Prevalence ~5% in general adult population; higher in HIV (up to 40%), Parkinson disease, and other neurologic conditions.
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Risk factors
- HIV/AIDS — severe and refractory disease
- Parkinson disease and other parkinsonian syndromes
- Neurologic conditions: stroke, spinal cord injury, depression, tardive dyskinesia
- Immunosuppression (transplant, chemotherapy)
- Cold dry weather, emotional stress
- Medications: lithium, interferon, EGFR inhibitors, neuroleptics
Pathophysiology
Multifactorial. Malassezia (M. furfur, M. globosa, M. restricta) — a lipophilic commensal yeast — metabolizes sebum lipids into irritating free fatty acids that trigger inflammation in susceptible hosts. Increased sebum production, abnormal lipid composition, and altered innate immunity contribute. Not a simple infection — represents an inflammatory response to fungal antigens.
Clinical presentation
Symptoms
- Mild pruritus or burning, especially scalp
- Visible scaling and erythema, often worse in winter
- Cosmetic concern, embarrassment
Signs / physical exam
- Scalp: fine flaky to thick greasy yellow scale; diffuse or patchy; erythema
- Face: erythematous patches with greasy scale in eyebrows, glabella, nasolabial folds, mustache/beard, postauricular sulcus, external auditory canal
- Chest: petaloid erythematous patches in midline sternal region
- Intertriginous: erythematous macerated plaques in axillae, inguinal folds, intergluteal cleft, umbilicus
- Infant cradle cap: thick adherent greasy yellow scale on vertex; non-pruritic; may extend to face, ears, neck, diaper area
Classic findings
Greasy yellow scale on erythematous base in sebaceous distribution; nasolabial fold involvement; postauricular fissures.
Differential diagnosis
- Psoriasis (sebopsoriasis overlap) — Sharply demarcated thick silvery scale, extensor surfaces, nails, Auspitz sign
- Atopic dermatitis — Pruritus prominent, flexural distribution, personal/family atopy
- Tinea capitis (children) — Patchy alopecia with scale and broken hairs; KOH/fungal culture positive; black-dot ringworm
- Rosacea — Centrofacial erythema with papules/pustules and telangiectasias; can coexist with seb derm
- Lupus (subacute cutaneous) — Photo-distributed annular or psoriasiform plaques; ANA/SSA positive
- Pityriasis versicolor — Hypo/hyperpigmented finely scaling macules on trunk; spaghetti-and-meatballs on KOH
- Langerhans cell histiocytosis (infants) — Recalcitrant seborrheic-like scalp/diaper eruption with petechiae, hepatosplenomegaly, lytic bone lesions
Diagnostic workup
Diagnostic criteria
Clinical: scaling and erythema in characteristic sebaceous distribution with chronic relapsing course.
Labs
- Clinical diagnosis
- Consider HIV testing if sudden, severe, or refractory disease, especially in young adults
- KOH preparation if tinea or pityriasis versicolor cannot be excluded
- Skin biopsy rarely needed; shows spongiosis with neutrophils at follicular ostia, parakeratosis
Imaging
- Not indicated
Diagnostic algorithm
| Site | Typical Lesion | Preferred Therapy |
|---|---|---|
| Scalp (adult) | Greasy yellow scale, erythema | Ketoconazole/selenium sulfide/zinc pyrithione shampoo 2-3x/wk |
| Face / nasolabial folds | Erythematous patches with greasy scale | Ketoconazole 2% cream + low-potency steroid or TCI |
| Intertriginous | Macerated erythematous plaques | Ketoconazole/ciclopirox cream + short low-potency steroid |
| Infant scalp (cradle cap) | Thick adherent yellow scale | Mineral oil/emollient + gentle brushing; ketoconazole 2% if persistent |
| Severe / HIV-associated | Widespread, refractory | Combination topical + oral itraconazole; treat HIV |
Treatment
First-line
- Adult scalp (dandruff/mild-moderate): ketoconazole 2% shampoo, selenium sulfide 2.5% shampoo, zinc pyrithione 1-2% shampoo, ciclopirox 1% shampoo, or coal tar shampoo — 2-3x/week, lather and leave on 5 min before rinsing
- Adult scalp (severe/plaque): high-potency topical corticosteroid solution/foam — clobetasol 0.05%, fluocinonide — short courses (≤2 weeks) over antifungal shampoo base
- Face/intertriginous: topical antifungal — ketoconazole 2% cream, ciclopirox 0.77% cream BID + low-potency topical corticosteroid (hydrocortisone 1%) or topical calcineurin inhibitor (tacrolimus, pimecrolimus) for short pulse
- Topical roflumilast 0.3% foam — PDE4 inhibitor, FDA-approved for scalp/body seb derm ages ≥9
- Infant cradle cap: emollient (mineral oil, petrolatum) overnight, gentle brushing, baby shampoo; mild ketoconazole 2% cream short course if persistent — self-limited
HIV-associated severe / refractory
- Combine topical antifungal + topical corticosteroid + intensive scalp shampoo regimen
- Address underlying HIV with antiretroviral therapy
- Oral itraconazole 200 mg/day × 1-2 weeks for severe widespread disease
Second-line / adjunct
- Oral itraconazole or fluconazole pulse therapy for refractory adult disease
- Topical lithium succinate/gluconate (off-label, available in Europe)
- Photodynamic therapy or low-dose narrowband UVB for stubborn facial disease
- Avoid greasy ointments which can worsen Malassezia overgrowth
Complications
- Cosmetic distress, social embarrassment
- Secondary bacterial infection from scratching/maceration
- Otitis externa from auditory canal involvement
- Steroid-induced atrophy, telangiectasia, perioral dermatitis from chronic high-potency use
- Erythroderma (rare, in HIV/immunocompromised)
PANCE pearls
- Sudden severe seborrheic dermatitis in a young adult should prompt HIV testing.
- Seborrheic dermatitis classically spares the upper eyelids and lateral canthus (unlike atopic blepharitis).
- Cradle cap is self-limited — reassure parents and treat conservatively with emollients first.
- Sebopsoriasis describes overlapping features and may respond better to vitamin D analogues (calcipotriene) in addition to antifungals.
- Beard area (sycosis-like) seb derm responds well to ketoconazole cream — patients often misdiagnosed as folliculitis.
References
- AAD 2014 — Guidelines of Care for the Management of Seborrheic Dermatitis (Clark et al., Am Fam Physician 2015; AAD work group)
- Cochrane 2014 — Topical Antifungals for Seborrhoeic Dermatitis (Okokon et al., Cochrane Database Syst Rev 2015)
- AAFP — Diagnosis and Treatment of Seborrheic Dermatitis (Clark et al., Am Fam Physician 2015)
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