Secondary Scarring Alopecia: Diagnosis and Treatment
Definition and Key Distinction
Secondary scarring alopecia occurs when hair follicles are destroyed as "innocent bystanders" in diseases primarily affecting the dermis or scalp, rather than targeting the follicle itself—this fundamentally differs from primary scarring alopecia where the follicle is the primary target. 1, 2, 3
Secondary scarring alopecia results from:
- Connective tissue diseases (systemic lupus erythematosus, scleroderma) 1
- Infections (bacterial, fungal, viral) 1, 2
- Physical trauma (burns, radiation, mechanical injury) 2
- Neoplasms (rarely) 1, 2
- Granulomatous diseases 1
- Bullous diseases 1
Diagnostic Approach
Clinical Examination
Examine for follicular ostia disappearance on dermoscopy—their absence with lack of yellow dots, exclamation mark hairs, and cadaverized hairs distinguishes scarring from non-scarring alopecia. 4
Look for these specific features:
- Signs of the underlying systemic disease (skin lesions, systemic symptoms) 1
- Associated scalp inflammation, scaling, or abnormal skin texture 5
- Distribution pattern (does it follow trauma, radiation fields, or systemic disease patterns?) 2
Dermoscopy (Trichoscopy)
Use dermoscopy as your first-line diagnostic tool to guide biopsy site selection and differentiate scarring from non-scarring conditions. 1, 4
- Absence of follicular openings indicates permanent follicular destruction 4
- Presence of yellow dots and exclamation mark hairs suggests non-scarring alopecia areata instead 4
Laboratory Testing
When diagnosis is uncertain, obtain targeted tests based on clinical suspicion of the underlying systemic disease:
- Fungal culture if tinea capitis or deep fungal infection suspected 5
- Serology for lupus erythematosus (ANA, anti-dsDNA) if systemic lupus suspected 5
- Serology for syphilis if secondary syphilis in differential 5
- Bacterial culture if bacterial infection suspected 1
Histopathology
Perform scalp biopsy when diagnosis remains uncertain after clinical and dermoscopic examination—this is the ultimate diagnostic tool for secondary scarring alopecia. 1, 4
- Biopsy shows follicular destruction with fibrous tissue replacement 3
- Inflammatory infiltrate pattern helps identify the underlying cause 1
- Detection of the underlying disorder may be difficult in end-stage lesions, so biopsy early when inflammation is active 2
Treatment Algorithm
Primary Strategy
Treat the underlying systemic disease or remove the causative factor—this is the single most important therapeutic intervention. 1
Specific approaches:
- For connective tissue diseases: Immunosuppressive therapy targeting the systemic condition 1
- For infections: Appropriate antimicrobial therapy (oral antifungals for tinea capitis, antibiotics for bacterial infections) 1
- For trauma/burns: Prevention of further injury 2
Adjunctive Topical Therapy
Apply topical anti-inflammatory treatments to active lesions while addressing the underlying cause. 1
Surgical Options
Consider hair transplantation or surgical scar revision only for localized, stable scars after the underlying condition is controlled. 2
Critical Pitfalls to Avoid
- Do not delay biopsy in uncertain cases—end-stage scarring makes diagnosis of the underlying cause extremely difficult 2
- Do not confuse secondary scarring alopecia with primary scarring alopecia (like lichen planopilaris or discoid lupus)—the former requires treating an external disease process, while the latter targets the follicle directly 6, 3
- Do not assume stress caused the scarring—psychological stress impacts quality of life but does not cause cicatricial alopecia 4
- Do not offer false hope for hair regrowth—once follicular destruction and scarring occur, hair loss is permanent 2, 3
Prognosis
Hair loss is permanent once follicular destruction and scarring are complete—early diagnosis and aggressive treatment of the underlying condition are essential to prevent progression. 2, 3