In a patient presenting with hair loss, what does scalp tenderness suggest about the underlying cause?

Scalp Tenderness in Hair Loss: Diagnostic Significance

Scalp tenderness in a patient with hair loss strongly suggests an inflammatory or infectious process rather than autoimmune alopecia areata, and should prompt immediate evaluation for scarring alopecias, tinea capitis, or folliculitis decalvans.

Key Diagnostic Distinction

Alopecia areata, the most common autoimmune cause of patchy hair loss, characteristically presents with normal-appearing scalp without tenderness, pain, or inflammation 1, 2. The presence of scalp tenderness fundamentally changes your differential diagnosis and requires urgent evaluation to prevent permanent scarring.

Conditions Associated with Scalp Tenderness

Scarring (Cicatricial) Alopecias

• Folliculitis decalvans presents with inflamed papules, pustules, and crusts at the edges of lesions, accompanied by tenderness and pain 3
• Lichen planopilaris typically shows peripilar erythema and scaling with associated discomfort 3
• Frontal fibrosing alopecia may present with tenderness along the receding hairline 3
• Discoid lupus erythematosus causes inflammatory scarring alopecia with scalp tenderness 4

Infectious Causes

• Tinea capitis presents with scalp inflammation, scaling, and tenderness, requiring fungal culture for definitive diagnosis 1, 5, 2
• The scalp inflammation in tinea capitis distinguishes it from the smooth, non-inflamed patches of alopecia areata 1

Critical Clinical Algorithm

When encountering scalp tenderness with hair loss:

1. Examine for scarring: Look for loss of follicular ostia, which indicates irreversible damage requiring aggressive early treatment 3, 4

2. Assess for inflammation: Presence of erythema, pustules, crusts, or scaling points toward infectious or inflammatory scarring alopecia rather than alopecia areata 1, 3

3. Perform dermoscopy immediately: This non-invasive tool differentiates conditions—yellow dots and exclamation mark hairs indicate alopecia areata (non-tender), while perifollicular scaling and erythema suggest scarring alopecia 1, 6

4. Obtain fungal culture if any inflammation present: This is mandatory before treatment, as incorrect clinical diagnosis is the most common cause of treatment failure 1

5. Consider urgent scalp biopsy: Strongly indicated for any suspected scarring alopecia to enable early aggressive treatment and prevent permanent hair loss 4

Common Pitfall to Avoid

Do not assume all patchy hair loss is alopecia areata—the presence of tenderness, inflammation, or scarring mandates different diagnostic workup and treatment 1, 2. Alopecia areata presents with well-demarcated patches on normal-appearing, non-tender scalp with preserved follicular ostia 2, 3. Missing a scarring alopecia leads to irreversible hair loss that could have been prevented with early intervention 4.