Which of the following conditions cause scarring alopecia: Alopecia (hair loss) areata, Lichen Planopilaris, or Telogen (a phase of hair growth) Effluvium?

Lichen Planopilaris is the Only Condition That Causes Scarring Alopecia

Among the options of Alopecia areata, Lichen Planopilaris, and Telogen Effluvium, only Lichen Planopilaris causes scarring alopecia. 1

Characteristics of Each Condition

Lichen Planopilaris

• Primary feature: Causes permanent scarring alopecia 1, 2
• Pathophysiology: Lymphocytic inflammation targets the bulge region (where hair follicle stem cells reside), leading to permanent destruction of hair follicles 3
• Clinical presentation:
  • Follicular hyperkeratosis
  • Perifollicular erythema
  • Loss of follicular orifices
  • Commonly affects vertex and parietal scalp
  • Symptoms include itching, scaling, burning, and tenderness 1
• Histopathology: Shows lichenoid lymphocytic infiltrate at the bulge region with CD8+ T cells predominating over CD4+ T cells 3

Alopecia Areata

• Primary feature: Non-scarring alopecia 4
• Pathophysiology: Autoimmune-mediated attack on hair follicles that spares the stem cells, allowing potential for regrowth 4
• Clinical presentation:
  • Smooth, non-inflamed patches of hair loss
  • Exclamation mark hairs at the periphery of expanding patches
  • Affected skin appears normal or slightly reddened 4, 5
• Prognosis: Hair follicles are preserved, maintaining potential for recovery even in longstanding disease 4

Telogen Effluvium

• Primary feature: Non-scarring, diffuse hair shedding 4
• Pathophysiology: Premature shift of growing (anagen) hairs into the resting (telogen) phase
• Clinical presentation: Diffuse thinning without inflammation or scarring
• Prognosis: Usually reversible once the triggering factor is removed 5

Diagnostic Differentiation

The key distinction between these conditions lies in whether the hair loss is scarring (cicatricial) or non-scarring:

1. Scarring alopecia (Lichen Planopilaris):

   • Permanent destruction of hair follicles
   • Loss of follicular openings on clinical examination
   • Histologically shows fibrosis and destruction of hair follicle architecture 1, 2

2. Non-scarring alopecia (Alopecia Areata and Telogen Effluvium):

   • Hair follicles remain intact
   • Follicular openings preserved
   • Potential for hair regrowth 4, 5

Clinical Pearls and Pitfalls

• Early scarring alopecia can sometimes be mistaken for alopecia areata, making careful examination crucial 4
• Frontal fibrosing alopecia is a clinical variant of lichen planopilaris that primarily affects postmenopausal women with progressive frontal hairline recession 6
• Even "normal-appearing" scalp areas in patients with lichen planopilaris may show histological evidence of inflammation, suggesting it may be a more generalized process than clinically apparent 7
• Dermoscopy is valuable for differentiating between these conditions - showing yellow dots and exclamation mark hairs in alopecia areata versus perifollicular erythema and loss of follicular openings in lichen planopilaris 5

In summary, when evaluating hair loss, determining whether the process is scarring or non-scarring is essential for diagnosis and management. Among the three conditions presented, only lichen planopilaris results in scarring alopecia with permanent hair loss.