What is the diagnosis and treatment for an adult with no significant past medical history presenting with a scaling red patch on the face that is sometimes itchy?

Scaling Red Patch on Face: Diagnosis and Management

The most likely diagnosis is seborrheic dermatitis or facial eczema, and initial treatment should consist of a low-potency topical corticosteroid combined with emollient therapy, avoiding soap and using gentle cleansers instead. 1, 2, 3

Differential Diagnosis to Consider

The key differentials for a scaling red patch on the face include:

• Seborrheic dermatitis: Characterized by greasy (not dry) yellowish scaling with erythema, typically affecting the nasolabial folds, central face, and scalp, often with associated dandruff 3
• Atopic dermatitis (eczema): Presents with dry, scaly, erythematous patches with pruritus; may have personal or family history of atopy (asthma, hay fever) 1
• Allergic contact dermatitis: Facial and eyelid involvement that is disproportionately severe suggests this diagnosis; common allergens include nickel, fragrances, preservatives, and cosmetics 4, 5
• Irritant contact dermatitis: Results from direct chemical damage from soaps, detergents, or other irritants 4

Critical History and Examination Points

History to obtain:

• Duration and pattern of symptoms (intermittent vs. constant) 1
• Presence and severity of itching—essential for eczema diagnosis 1
• Personal or family history of atopic disease (asthma, hay fever, childhood eczema) 1
• Aggravating factors including exposure to soaps, cosmetics, hair products, or other potential irritants 1
• Sleep disturbance from itching 1
• Previous treatments and their effectiveness 1

Examination findings:

• Location and distribution: Seborrheic dermatitis favors nasolabial folds and central face; eczema may affect cheeks more diffusely 3
• Scale characteristics: Greasy yellowish scales suggest seborrheic dermatitis; dry white scales suggest eczema 3
• Look for signs of secondary bacterial infection (crusting, weeping, honey-colored exudate) 1
• Assess for grouped vesicles or punched-out erosions suggesting herpes simplex infection 1

Initial Treatment Algorithm

Step 1: Foundation therapy (all patients)

• Discontinue all soaps and replace with gentle dispersible cream cleansers 1
• Apply emollients liberally at least twice daily, most effective immediately after washing 1
• Avoid extremes of temperature and known irritants 1

Step 2: Anti-inflammatory therapy

• Apply a low-potency (mild) topical corticosteroid to affected areas 1-2 times daily for active inflammation 1, 2
• For seborrheic dermatitis specifically, topical steroids are highly effective and comparable to azole antifungals for total clearance 2
• Mild steroids are as effective as strong steroids for facial eczema in short-term use, with better safety profile 2
• Continue for 1-2 weeks until inflammation resolves 1

Step 3: Maintenance

• Continue emollient therapy indefinitely as foundation treatment 1
• For seborrheic dermatitis, consider maintenance with antifungal agents or lithium salts after initial steroid course 2

When to Suspect Secondary Infection

Bacterial infection is indicated by:

• Crusting or weeping lesions 1
• Honey-colored exudate 1
• Failure to respond to standard treatment 1
• If suspected, obtain bacterial swabs and consider adding topical or systemic antibiotics 1

Herpes simplex infection (eczema herpeticum—a medical emergency):

• Multiple uniform "punched-out" erosions or vesicles 1
• Requires immediate systemic antiviral therapy 1

Common Pitfalls to Avoid

• Do not undertreat due to steroid phobia: Low-potency topical corticosteroids are safe and effective for facial use when used appropriately 1, 2
• Do not neglect emollient therapy: This is the foundation of treatment and must be continued even when inflammation resolves 1
• Do not assume all facial redness is rosacea: A scaling component strongly suggests eczema or seborrheic dermatitis rather than rosacea 6, 7
• Do not overlook contact dermatitis: If the pattern is unusual or disproportionately affects eyelids, consider allergic contact dermatitis and potential need for patch testing 5

When to Refer or Investigate Further

Consider dermatology referral if:

• No response to first-line treatment with low-potency topical steroids after 2-4 weeks 5
• Severe disease affecting quality of life 5
• Diagnostic uncertainty 6

Consider allergy testing if:

• Facial and eyelid involvement is disproportionately severe, suggesting allergic contact dermatitis 5
• Pattern suggests contact allergy (unusual distribution, aggravation by topical products) 5