What is the likely diagnosis and first‑line treatment for flaky, plaque‑like lesions on the scalp and face?

Flaky Skin Plaques on Scalp and Face: Diagnosis and Treatment

The most likely diagnosis is seborrheic dermatitis, and first-line treatment consists of ketoconazole 2% shampoo or cream combined with a low-potency topical corticosteroid (hydrocortisone 1%) for 2-4 weeks maximum on the face. 1, 2, 3

Diagnostic Approach

Key distinguishing features favor seborrheic dermatitis over psoriasis:

• Greasy, yellowish scales (not silvery-white) with poorly defined erythematous patches in seborrheic areas—scalp, nasolabial folds, eyebrows, central face 1, 4, 3
• Less well-demarcated borders compared to the sharp, indurated plaques typical of psoriasis 1, 2
• Distribution pattern: scalp, face (especially nasolabial folds, eyebrows), and chest are classic for seborrheic dermatitis 1, 4

If psoriasis is suspected instead, look for:

• Thick, silvery-white scales on well-demarcated, indurated plaques 1, 5
• Nail changes (pitting, onycholysis, oil-drop sign)—present in ~50% of psoriasis patients and predict psoriatic arthritis in 90% of cases 1
• Extensor surfaces (elbows, knees), umbilicus, and postauricular areas are more typical 6, 5

Perform skin biopsy if:

• Diagnostic uncertainty persists after clinical examination 1
• No response after 4 weeks of appropriate first-line therapy 1, 2
• Atypical presentation raises concern for pemphigus vulgaris or cutaneous T-cell lymphoma 1, 7

First-Line Treatment for Seborrheic Dermatitis

Scalp Involvement

Ketoconazole 2% shampoo achieves 88% clinical response and is the preferred first-line agent: 2, 3

• Massage 1-2 teaspoonfuls into wet scalp 8
• Leave on for 2-3 minutes, rinse thoroughly 8
• Repeat application and rinse again 8
• Use twice weekly initially, then taper to once weekly for maintenance 2, 3

Alternative antifungal shampoos include:

• Selenium sulfide 1% shampoo (leave on 2-3 minutes before rinsing) 2, 8
• Coal tar 1% preparations to reduce inflammation and scaling 2, 3

For thick, adherent scales:

• Apply salicylic acid 0.5-2% lotion once daily, increasing to twice daily if tolerated 2
• Avoid salicylic acid 6% in children under 2 years due to Reye syndrome risk 2

Topical corticosteroid solutions/foams for scalp (class 1-7) can be used for up to 4 weeks: 6

• Clobetasol 0.05% solution or fluocinonide 0.05% solution for severe inflammation 6
• Solutions and foams are preferred over creams/ointments due to hair making traditional formulations difficult to apply 2

Facial Involvement

Ketoconazole 2% cream applied twice daily is first-line: 2, 3

• Continue for 2-4 weeks until lesions clear 2, 3
• Taper to once daily or every other day for maintenance 2

Add low-potency topical corticosteroid for significant erythema/inflammation:

• Hydrocortisone 1% cream or prednicarbate 0.02% cream applied twice daily 6, 1, 2
• Limit facial corticosteroid use to 2-4 weeks maximum to avoid skin atrophy, telangiectasia, and tachyphylaxis 6, 1, 2
• Never use medium- or high-potency steroids (triamcinolone, mometasone, clobetasol) on the face due to unacceptable adverse effects 2

Critical supportive measures:

• Avoid all alcohol-containing preparations on the face—they significantly worsen dryness and trigger flares 6, 2, 9
• Use mild, pH-neutral (pH 5) non-soap cleansers to preserve natural skin lipids 1, 2
• Apply fragrance-free moisturizers with urea 10% or glycerin to damp skin immediately after cleansing 2
• Avoid perfumes, deodorants, and harsh soaps that strip the lipid barrier 2

First-Line Treatment for Psoriasis (If Diagnosed Instead)

Scalp Psoriasis

Class 1-7 topical corticosteroids for up to 4 weeks are recommended as initial therapy: 6

• Clobetasol 0.05% solution or halobetasol propionate ointment for thick plaques 6
• Demonstrated 68-92% improvement in physician global assessment scores after 2 weeks 6

Vitamin D analogs (calcipotriene) can be used alone or combined with corticosteroids 6

Facial/Body Psoriasis

For plaque psoriasis not involving intertriginous areas:

• Class 2-5 (moderate to high potency) corticosteroids for up to 4 weeks 6
• Class 1 (ultrahigh-potency) for thick, chronic plaques 6
• Lower potency corticosteroids must be used on face and intertriginous areas to prevent atrophy 6

Gradual tapering after clinical improvement is recommended to prevent rebound, though exact protocols are not well-established 6

When to Escalate or Refer

Refer to dermatology if:

• Diagnostic uncertainty or atypical presentation 1, 2
• Failure to respond after 4 weeks of appropriate first-line therapy 1, 2
• Recurrent severe flares despite optimal maintenance therapy 1, 2
• Suspected psoriatic arthritis (joint swelling, morning stiffness >2 hours unresponsive to NSAIDs) 6

For moderate-to-severe psoriasis (>10% body surface area):

• Methotrexate is traditional first-line systemic therapy 6
• TNF-α inhibitors, IL-17 inhibitors, or IL-23 inhibitors for severe disease 6
• Narrow-band UVB phototherapy or PUVA for refractory cases 6

Common Pitfalls to Avoid

In seborrheic dermatitis:

• Undertreatment due to corticosteroid fear—use appropriate potency for adequate duration, then taper 2
• Confusing persistent itching with treatment failure—mild burning/itching from inflammation can persist for days after yeast elimination 2
• Using non-sedating antihistamines—they provide no benefit in seborrheic dermatitis 2

In psoriasis:

• Abrupt withdrawal of topical corticosteroids can cause rebound flares 6
• Prolonged high-potency corticosteroid use on face/forearms increases risk of atrophy, striae, and telangiectasia 6
• Missing nail changes—90% of patients with nail psoriasis have or will develop psoriatic arthritis 1

Watch for secondary bacterial infection (crusting, weeping) requiring flucloxacillin, or herpes simplex superinfection (grouped erosions) requiring acyclovir 2, 3