Lichen Simplex

Lichen simplex is an eczematous dermatosis characterised by a small number of pruritic, heavily lichenified plaques or, very often, a single lesion.

Etiology

• Not all individuals are capable of developing lichenification, but for those that are, the following are contributing factors to the development of lichen simplex:
  • Patients are more readily conditioned to scratch when itchy
  • Stress
  • An atopic background

History

• Lichen simplex normally affects adults with a peak incidence of 30-50 years of age
• Woman are affected more than men
• Itch is often intense and can be out of proportion to the clinical findings

Clinical findings

• Distribution
  • Lesions can arise on any location that the patient can reach, however, the following are the most common sites:
    • Extensor forearms / elbows
    • Lower legs / ankles
    • The sides and nape of the neck, the latter is found predominantly in women. The scalp may also be involved
    • Vulva - which often presents with a symmetrical thickening, however the findings can be more pronounced on one side such that in right handed people the changes are often worse on the left and visa versa
    • Scrotum
• Morphology
  • Erythema is present in the early stages
  • Over time the skin becomes thickened (lichenified) centrally to form a scaly plaque, which may become hyperpigmented. Thickening of the skin can be substantial, sometimes developing warty, cribriform surfaces
  • Surrounding the central plaque are a group of firm, lichenoid papules
  • Erosions and ulceration can develop from scratching