LICHEN SIMPLEX CHRONICUS

The term lichen simplex chronicus (LSC) refers to the changes of the skin that occur after chronic rubbing. The term lichenified refers to skin thickening with accentuation of the skin markings.

Patients with anxiety, and in particular those with obsessive–compulsive disorder, have a significantly increased risk of developing LSC.
Prurigo nodularis is a very similar condition where nodules form.
See also LSC of the groin for NSFW pictures.

Clinical

The skin becomes lichenified in a localized plaque. The plaque may range in size from 1-10 cm. Linear excoriations or erosions may be apparent. Any area of the body may be affected, but typical locations include the scrotum or vulva and the ankle. The patient with atopic dermatitis (AD) often develops LSC. In fact, any lichenification in an patient with AD is from scratching or rubbing until proven otherwise. Psoriatic lesions may be chronically scratched giving rise through Koebnerization to psoriatic LSC.

Treatment

Tell the patient, "Don't scratch! I will give you a potent steroid to take away the itch. And if you don't scratch for 3 weeks, this will go away."
A potent topical steroid, e.g., clobetasol or Cordran tape, should be prescribed.
Cover at night if needed.
Once cleared, the patient may benefit from daily moisturization to prevent dry skin, itching, and eczema which can trigger LSC. See dry skin handout.
Intralesional steroid, e.g., triamcinolone 5-10 mg/cc may be needed in recalcitrant cases.
Topical doxepin QHS can be helpful.

FDA-Approved for Prurigo Nodularis

Dupixent
Nemolizumab

It is of vital importance that the patient be told not to scratch. I often say, "It doesn't matter how strong a steroid I give you, if you continue to scratch, you'll continue to have it." This statement often prompts the patient to further define why it is s/he scratches. Is it a habit that is easily broken? Is it because it itches? Or is it a stress reliever? Or does the patient deny scratching altogether?

A potent topical steroid ointment BID for 3 weeks is of great help. It often gives enough relief to allow the patient to stop scratching and break the cycle. A steroid-impregnated tape is also helpful (e.g., Cordran) as it imposes a barrier to the scratching. Occluding the steroid at night often serves the same purpose. Intralesional Kenalog (e.g., 5 mg/cc) is often employed for smaller lesions. As the patient improves, s/he should keep the steroid on hand for any itchy areas. These patients are prone to this condition and relapse is frequent. Topical doxepin at night can be helpful to prevent the itch. This topical medicine can actually cause drowsiness, thus its used QHS.

For resistant cases, dupilumab and nemolizumab which are FDA-approved for prurigo nodularis would be excellent here.

Additional Pictures

Chronic rubbing of the skin can cause tremendous thickening (lichenification).

A mix of LSC and prurigo nodularis.

RegionalDerm

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