Dermatology · PANCE / PANRE

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

Site-based therapy for seborrheic dermatitis.

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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