What is the diagnosis and treatment for small, itchy patches on the scalp?

Small Itchy Patches on Scalp: Diagnosis and Treatment

Most Likely Diagnosis

The most common causes of small, itchy patches on the scalp are seborrheic dermatitis (dandruff), tinea capitis (fungal infection), scalp psoriasis, or atopic dermatitis. 1, 2, 3, 4

Diagnostic Approach

Key Clinical Features to Distinguish

• Seborrheic dermatitis/Dandruff: Presents as generalized, diffuse scaling with greasy, yellowish scales, often with itch as a leading symptom 1, 3, 4, 5

• Tinea capitis: May present with patchy scaling that can be difficult to distinguish from dandruff, but look for associated hair loss, broken hairs, or inflammatory changes 1, 2, 4

• Scalp psoriasis: Characterized by well-demarcated, thick, silvery-white scales with underlying erythema; itch and scaling are the leading distressing symptoms 6, 4

• Atopic eczema: Consider if there is personal or family history of atopy (asthma, hay fever), general dry skin, or flexural involvement elsewhere 7

Essential Evaluation Steps

• Examine the scalp carefully for distribution pattern (diffuse vs. patchy), scale characteristics (fine vs. thick), presence of erythema, and any hair loss 3, 8, 4

• Check for associated findings: facial involvement (25% in psoriasis), nail changes (40% in psoriasis), or flexural eczema elsewhere 7, 6

• Consider fungal culture or KOH preparation if tinea capitis is suspected, especially if there are patches with hair loss or the presentation is atypical 2, 4

• Rule out secondary bacterial infection if there is crusting, weeping, or sudden worsening of previously stable disease 7

Treatment Algorithm

First-Line Treatment for Most Common Causes

For seborrheic dermatitis/dandruff (most common):

• Ketoconazole 2% cream or shampoo applied to affected areas once or twice daily 9, 5

  • For scalp seborrheic dermatitis, apply twice daily for four weeks or until clinical clearing 9
  • Anti-fungal agents are the mainstay of treatment 5

• Topical corticosteroids (mild-to-moderate potency) for inflammatory component 5

  • Use appropriate potency based on severity and location 7

For suspected tinea capitis:

• Systemic antifungal therapy is required (topical treatment alone is insufficient) 2
• Refer for appropriate oral antifungal prescription after confirmation 2

For scalp psoriasis:

• Topical corticosteroids are the most frequently used and effective treatment 6

  • Apply a few times per week for long-term management 6
  • Lotions or emulsions are preferred over ointments for scalp application 6

• Calcipotriol can be considered as an alternative or adjunct 6

For atopic eczema:

• Liberal use of emollients as the foundation of treatment 7
• Topical corticosteroids with potency appropriate to age, site, and disease extent 7
• Time for patient education about application technique and quantities is essential 7

Important Caveats

• Avoid empiric dietary restriction unless there is clear correlation with symptoms; this is rarely beneficial in adults and should only be tried in selected infants under professional supervision 7

• Consider allergic contact dermatitis if disease is recalcitrant to standard therapy, has unusual distribution, or worsens with topical treatments 7

  • Common allergens include fragrances, preservatives, neomycin, and even some topical corticosteroids 7

• Secondary bacterial infection with Staphylococcus aureus should be suspected if there is sudden deterioration with crusting or weeping 7

• Duration matters: Most patients require longer treatment than initially prescribed; for seborrheic dermatitis, continue for 4 weeks or until clearing 9, 5

When to Refer

• Refer to dermatology if diagnosis is uncertain, disease is severe or recalcitrant to initial treatment, or if patch testing for contact dermatitis is needed 7

• Consider skin biopsy only if diagnosis remains unclear after clinical evaluation 7