Differentiating Seborrheic Dermatitis from Melasma on the Malar Region
Seborrheic dermatitis presents with erythematous patches, yellow-oily scales, and fine desquamation on the malar area, while melasma presents as hyperpigmented macules without scale or inflammation—these are clinically distinct conditions that should not be confused. 1
Key Clinical Distinguishing Features
Seborrheic Dermatitis Characteristics
- Erythema with scaling: Symmetric, poorly defined erythematous patches with yellow, oily scales and superficial flaking on the nasolabial folds, glabella, and malar regions 1
- Associated pruritus: Itching is typically present 2
- Distribution pattern: Affects sebaceous-rich areas including scalp (95% of facial cases), eyebrows, nasolabial folds, and chest 3, 4
- In darker skin: Erythema may be less apparent; hypopigmented, slightly scaly areas with postinflammatory pigmentary changes may be the presenting sign 1, 5
- Texture changes: Visible scaling and flaking that can be felt on palpation 4
Melasma Characteristics
- Hyperpigmentation without inflammation: Brown to gray-brown macules and patches with no erythema or scale
- Smooth surface: No scaling, flaking, or textural changes
- No pruritus: Asymptomatic pigmentary disorder
- Symmetric distribution: Typically centrofacial pattern (forehead, cheeks, upper lip, nose)
- Hormonal/sun exposure triggers: Associated with pregnancy, oral contraceptives, and UV exposure
Diagnostic Approach
Physical Examination Findings to Assess
- Palpate for scale: Seborrheic dermatitis will have palpable scale and texture; melasma is smooth 1
- Assess for erythema: Present in seborrheic dermatitis (though may be subtle in darker skin), absent in melasma 1, 5
- Check other seborrheic sites: Examine scalp, eyebrows, nasolabial folds, chest—95% of facial seborrheic dermatitis patients have scalp involvement 3
- Wood's lamp examination: Can help differentiate—melasma shows enhanced pigmentation, seborrheic dermatitis shows no pigmentary enhancement
- Look for associated conditions: Seborrheic dermatitis is more pronounced in Parkinson's disease, HIV, and Down syndrome 3, 6
Clinical Pitfall
In patients with darker skin, seborrheic dermatitis may present with hypopigmented patches that could be mistaken for pigmentary disorders, but the presence of fine scale and history of inflammation distinguishes it from melasma. 5
Treatment Algorithm
For Confirmed Seborrheic Dermatitis of the Face
First-line therapy: Topical ketoconazole 2% cream applied once daily to affected areas for 2-4 weeks 7, 4
Adjunctive short-term therapy (if significant inflammation):
- Low-potency topical corticosteroid for maximum 2 weeks to control inflammation and itching 3, 6
- Caution: Avoid long-term corticosteroid use on the face due to risk of skin atrophy, telangiectasia, and tachyphylaxis 6
- Avoid alcohol-containing preparations as they increase facial skin dryness 6
Maintenance therapy:
- Due to chronic, relapsing nature, intermittent antifungal therapy is necessary 3, 6
- Gentle skin care with mild, non-soap cleansers and emollients to reduce dryness 6
Treatment duration: Continue for full prescribed duration (2-4 weeks) even if symptoms improve sooner 6, 7
For Confirmed Melasma
- Topical hydroquinone, tretinoin, or triple combination therapy
- Strict sun protection with broad-spectrum SPF
- No role for antifungal or anti-inflammatory therapy
Critical Considerations
- Fungal pathophysiology: Seborrheic dermatitis involves Malassezia species metabolizing sebum triglycerides, producing irritating free fatty acids that trigger inflammation 3, 4, 2
- Co-existing conditions: Check for dry eye (25-40% co-occurrence), rosacea, and blepharitis in seborrheic dermatitis patients 3
- Skin of color modifications: Patients with darker skin and textured hair may require modified treatment approaches accounting for different hair washing frequencies 5
- If no improvement after 4 weeks: Redetermine the diagnosis 7