Seborrheic Dermatitis (Sebderm): Causes, Features & Treatment Overview

1. What is seborrheic dermatitis?

Seborrheic dermatitis is a chronic, relapsing inflammatory skin disease affecting sebaceous (oil-rich) areas:

• Scalp

• Face (especially eyebrows, nasolabial folds, glabella)

• Ears, presternal chest, upper back, body folds

It’s strongly associated with Malassezia (yeast), sebum, and abnormal immune response.

Prevalence: about 1–3% of the general population, much higher in HIV and neurologic disease (e.g. Parkinson’s).

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2. Pathophysiology (high-yield idea level)

Key components:(New England Journal of Medicine)

1. Malassezia overgrowth

   • Lipophilic yeast in sebaceous areas

   • Metabolizes sebum → free fatty acids → irritant + pro-inflammatory effect

2. Sebum & barrier dysfunction

   • SD occurs in sebum-rich areas; altered lipid composition and barrier function contribute.

3. Immune dysregulation

   • Exaggerated immune response to Malassezia in some people

   • Explains association with HIV and neurologic disorders.(Merck Manuals)

Think of SD as: “Malassezia + oily skin + abnormal immune reaction → chronic erythematous, greasy scaling.”

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3. Clinical features of seborrheic dermatitis

Adults

• Distribution (very important!)

  • Scalp: dandruff → diffuse, fine or coarse white/yellow greasy scales

  • Face: eyebrows, glabella, nasolabial folds, beard area

  • Ears: external ear canal, retroauricular folds (often fissuring behind ears)

  • Chest: ill-defined erythematous plaques with greasy scale over presternum

  • Body folds: axillae, groin, inframammary, umbilicus

• Morphology

  • Ill-defined erythematous patches/plaques

  • Greasy, yellowish scale

  • Mild–moderate pruritus (itch)

Infants (cradle cap)

• Age: first weeks–months of life

• Thick, greasy, yellow scales on scalp, sometimes involving face and folds

• Usually non-itchy, baby generally well

• Often resolves spontaneously in months

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4. How is seborrheic dermatitis different from psoriasis?

Psoriasis is a chronic immune-mediated disease with well-demarcated erythematous plaques and thick, dry, silvery scale, common on extensor surfaces (elbows, knees), scalp, sacrum, and associated with nail changes and arthritis.

Seborrheic dermatitis vs Psoriasis – exam comparison

Feature	Seborrheic dermatitis	Psoriasis
Distribution	Sebaceous areas: scalp, eyebrows, nasolabial folds, ears, presternal chest, flexural folds	Scalp, elbows, knees, lumbosacral area, umbilicus; often extensors
Borders	Ill-defined, diffuse	Sharply demarcated plaques
Scale	Thin, greasy, yellowish	Thick, dry, micaceous “silvery” scale
Pruritus	Mild–moderate, variable	Often significant
Nails	Usually normal	Pitting, onycholysis, subungual hyperkeratosis
Auspitz sign (pinpoint bleeding when scale removed)	Typically negative	Often positive
Systemic associations	HIV, Parkinson’s, neurologic disease	Psoriatic arthritis, metabolic syndrome, uveitis, etc.
Response to antifungals	Often improves with antifungal therapy	Minimal response to antifungals

There is an overlap called “sebopsoriasis” – psoriasis in seborrheic areas, with overlapping features.

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5. Other important differential diagnoses

From guidelines and reviews, frequent differentials include:(New England Journal of Medicine)

1. Atopic dermatitis (eczema)

   • Personal or family history of atopy

   • Flexural involvement, very pruritic, lichenification; onset usually childhood.

2. Tinea capitis / tinea corporis

   • Fungal infection; can mimic scalp SD or psoriasis.

   • Look for broken hairs, black dots, lymphadenopathy (especially in kids).

   • Confirm with KOH or fungal culture; tinea does not improve with typical SD treatment.

3. Contact dermatitis (allergic/irritant)

   • Well-demarcated in area of contact with cosmetic, shampoo, etc.; often more pruritic, vesicles possible.

4. Rosacea (face)

   • Central facial erythema, papules/pustules, telangiectasia, no significant scale.

5. Lupus erythematosus / secondary syphilis

   • Consider if systemic symptoms, photosensitivity, mucosal lesions, palmar/plantar rash, etc.

Key exam point:If the scalp looks “seborrheic,” but there is nail pitting or well-demarcated thick plaques on elbows/knees → think psoriasis first.

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6. Diagnosis

• Mostly clinical: based on typical distribution + greasy scale + chronic relapsing course.(AAFP)

• Dermoscopy: can help distinguish from psoriasis/tinea capitis in difficult scalp cases.(dermatologyadvisor.com)

• Biopsy: rarely needed; reserved for atypical cases or to rule out psoriasis, tinea, cutaneous lymphoma, etc.

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7. Management of seborrheic dermatitis

Principles:(AAFP)

1. Chronic disease → focus on control, not cure.

2. Combine anti-inflammatory + antifungal therapies.

3. Use low-potency steroids short-term; avoid chronic continuous use.

4. Maintenance: intermittent antifungal or medicated shampoo.
   

7.1 Scalp seborrheic dermatitis (dandruff to moderate SD)

First-line (mild–moderate): medicated shampoos

Use 2–3 times/week, leave on 5–10 minutes before rinsing; alternate agents if needed:

• Ketoconazole 2% shampoo – antifungal against Malassezia

• Ciclopirox 1% shampoo

• Zinc pyrithione, selenium sulfide, coal tar, salicylic acid shampoos

For exams, you can phrase:

Ketoconazole 2% shampoo, apply 2–3×/week to scalp, leave 5–10 minutes then rinse; continue for several weeks, then once weekly for maintenance.

If significant inflammation / itching:

• Add low- to mid-potency topical corticosteroid lotion/solution/foam: e.g. hydrocortisone 1%, betamethasone valerate 0.1% solution once–twice daily for 1–2 weeks, then taper.

Avoid: long-term daily steroids on scalp → atrophy, telangiectasia, tachyphylaxis.

7.2 Face and body (non-scalp) seborrheic dermatitis

1) Topical antifungals (mainstay)

• Ketoconazole 2% cream or ciclopirox 1% cream

• Apply once–twice daily to affected areas for 2–4 weeks; then intermittently for maintenance (e.g. 2–3×/week).(AAFP)

2) Low-potency topical corticosteroids (short courses)

• Hydrocortisone 1% cream bid for 5–7 days during flares, especially on face/folds.

• Avoid high-potency steroids on face → skin atrophy, telangiectasia, perioral dermatitis.

Evidence supports short courses of weak steroids + imidazole antifungal for non-scalp SD.(JDD Online)

3) Topical calcineurin inhibitors (TCIs)

• Tacrolimus 0.03–0.1% ointment or pimecrolimus 1% cream as steroid-sparing agents, particularly on face and intertriginous areas.(JDD Online)

• Good for long-term maintenance.

• Not first-line in some guidelines due to theoretical malignancy risk; use when steroids are contraindicated or for recurrent flares.

4) General skincare

• Gentle, non-soap cleansers; avoid harsh scrubs or strong alcohol-based products.

• Regular shampooing even with non-medicated shampoo helps reduce scale.
  

7.3 Severe, widespread, or refractory seborrheic dermatitis

Consider:(New England Journal of Medicine)

1. Screen for underlying conditions

   • HIV (especially if sudden, severe, or recalcitrant SD)

   • Neurologic disease (Parkinson’s)

2. Oral antifungals (short course)

   • Oral itraconazole, fluconazole, or terbinafine in selected, resistant cases under specialist guidance.

3. Newer non-steroidal options

   • PDE-4 inhibitors and “device” creams are emerging but more specialty-level/exam-advanced.(Dermatology Times)
     

7.4 Infantile seborrheic dermatitis (cradle cap)

Most cases are benign and self-limited.(DermNet®)

• First-line:

  • Emollient/oil (mineral oil, baby oil) to soften scale → gentle brushing/combing.

  • Mild baby shampoo.

• If persistent or inflamed:

  • Ketoconazole 2% shampoo/cream 2–3×/week for a few weeks.

  • Very short course of low-potency topical steroid (e.g. hydrocortisone 1% for a few days) if significant erythema/pruritus.

Avoid strong steroids, salicylic acid on infants, or aggressive manual removal.

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8. Quick exam pearls (especially vs psoriasis)

1. Distribution is king

   • SD = sebaceous: scalp, eyebrows, nasolabial folds, retroauricular, presternal, body folds.

   • Psoriasis = extensor plaques (elbows, knees), lumbosacral, scalp with thick plaques, nail pitting.

2. Type of scale

   • SD: thin, greasy, yellowish

   • Psoriasis: thick, dry, silvery, positive Auspitz sign.

3. Response to therapy

   • SD: improves with antifungal shampoos/creams ± mild steroids.

   • Psoriasis: responds better to stronger anti-inflammatory/immune-modulating therapy (e.g. vitamin D analogues, higher-potency steroids, biologics in severe disease).

4. Chronic and relapsing

   • Tell patients they will likely need intermittent maintenance (e.g. medicated shampoo once weekly).