6-10: Lichen Simplex Chronicus (Circumscribed Neurodermatitis)

Lichen simplex chronicus represents a self-perpetuating scratch-itch cycle that is hard to disrupt.

Intermittent itching incites the patient to scratch the lesions. Itching may be so intense as to interfere with sleep. Dry, hypertrophic, lichenified plaques appear on the neck, wrists, ankles, or perineum (Figure 6–6) (eFigure 6–11) (eFigure 6–12). The patches are rectangular, thickened, and hyperpigmented. The skin lines are exaggerated.

This disorder can be differentiated from plaque-like lesions such as psoriasis (redder lesions having whiter scales on the elbows, knees, and scalp and nail findings) (eFigure 6–13), lichen planus (violaceous, usually smaller polygonal papules), and nummular (coin-shaped) dermatitis (eFigure 6–14). Lichen simplex chronicus may complicate chronic atopic dermatitis or scabetic infestation.

For lesions in extragenital regions, superpotent topical corticosteroids are effective, with or without occlusion, when used twice daily for several weeks. In some patients, flurandrenolide (Cordran) tape may be effective, since it prevents scratching and rubbing of the lesion. The injection of triamcinolone acetonide suspension (5–10 mg/mL) into the lesions may occasionally be curative. Continuous occlusion with a flexible hydrocolloid dressing for 7 days at a time for 1–2 months may also be helpful. Dupilumab is a new treatment option for generalized disease or prurigo nodularis, its related condition. For genital lesions, see the section Pruritus Ani.

The disease tends to remit during treatment but may recur or develop at another site.