Lichen Simplex Chronicus

Description

• Lichen simplex chronicus (LSC) is a chronic dermatitis resulting from chronic, repeated rubbing or scratching of the skin. Skin becomes thickened with accentuated lines (“lichenification”).
• Definition/terminology (1):
  • LSC: localized lichenified plaques often with excoriations
  • Prurigo nodularis (PN): a chronic pruritic condition which is frequently more broadly distributed across multiple regions as nodules
  • Neurodermatitis: include other chronic itchy conditions, such as PN and atopic dermatitis

Epidemiology

Geriatric Considerations
Most common in middle-aged and elderly

Pediatric Considerations
Rare in preadolescents

Incidence

• Peak incidence: ages 35 to 50 years
• Predominant sex: females > males (2:1)

Prevalence
Common—affects 12% of the population

Etiology and Pathophysiology

• Itch–scratch cycle leads to a chronic dermatosis. Repeated scratching or rubbing causes inflammation and pruritus, which leads to continued scratching.
• Primary LSC: scratching secondary to nonorganic pruritus, habit or a conditioned response to stress/anxiety
• Common triggers are excess dryness of skin, heat, sweat, and psychological stress.
• Secondary LSC: begins as a pruritic skin disease that evolves into neurodermatitis, which persists after resolution of the primary condition. Precursor dermatoses include atopic dermatitis, contact dermatitis, lichen planus, stasis dermatitis, psoriasis, tinea, and insect bites.
• There is a possible relation between disease development and underlying neuropathy, particularly radiculopathy or nerve root compression.
• Pruritus-specific C neurons are temperature sensitive, which may explain itching that occurs in warm environments.

Risk Factors

• Anxiety disorders
• Dry skin
• Insect bites
• Pruritic dermatosis

General Prevention

Avoid common triggers such as psychological distress, environmental factors such as heat and excessive dryness, skin irritation, and the development of pruritic dermatoses.

Commonly Associated Conditions

• PN is a nodular variety of the same disease process.
• Atopic dermatitis
• Anxiety, depression, and obsessive-compulsive disorders