Diagnosis: Lichen simplex chronicus

The patient was diagnosed with lichen simplex chronicus (LSC), a chronic, localized, dry plaque of lichenification (thickened skin with accentuation of the normal skin lines) arising secondary to unremitting scratching, itching, and/or rubbing (the itch-scratch cycle). This condition is the result of recurrent mechanical trauma to a specific area of the skin. It may also develop as a superimposed disorder at the site of a previous condition that would initiate the essential pruritus, such as an insect bite or an allergic contact dermatitis. In simple terms, if the patient scratches a particular spot of skin, a calluslike thickening occurs. If the scratching continues, the nerves begin to say “scratch me,” causing the patient to develop a habit of scratching that spot of skin. The itch-scratch cycle of LSC often persists even when environmental triggers are removed and any underlying disease is treated.

LSC is defined as a neurodermatitis because it results from the patient’s uncontrollable desire to pick, dig, scratch, or rub the skin. Affected individuals generally do not deny their compulsive habit, and they usually describe the itch sensation as paroxysmal, severe, and intractable. The pruritus is intermittent and often increases during periods of emotional stress or inactivity, such as sleep.


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LSC usually occurs in adults, with the average age of onset between 30 and 50. Women are more frequently affected than men, and although the condition has no predilection for race, darker skin sometimes demonstrates follicular prominence and more severe secondary pigmentary alterations. Lesions typically occur on the nape of the neck and the lateral aspect of the lower leg, but they may develop on any part of the body. Most patients have only one or two plaques.

When diagnosing LSC, an elevated serum immunoglobulin E level can reveal the presence of an underlying diathesis; patch testing will help exclude allergic contact dermatitis as a cause. Skin biopsy usually is not required for the diagnosis, but such microscopic examination can help rule out psoriasis or mycosis fungoides. In this patient’s case, biopsy was performed. It revealed the characteristic histologic features of hyperkeratosis, acanthosis, pseudoepitheliomatous hyperplasia, and papillary dermal fibrosis seen with LSC.

Treatment is not generally required, unless the pruritus is severe. Most patients who seek medical treatment do so because the plaque is visible. Treatment requires attention to triggering factors, repair of the damaged epidermal layer, reduction in inflammation, and breaking the itch-scratch cycle. Triggers include endogenous factors (perspiration, dryness, emotional stress), exogenous irritants (scratching, warm temperatures, wool fibers, soaps, detergents, disinfectants), and contact and airborne allergens (dust mites, furry animals, and pollens).

Psychological factors appear to play a role in the development and exacerbation of the condition, with anxiety being highly prevalent in patients with LSC.

If the patient can completely refrain from scratching the lesion for four months, the defect will resolve itself. Some patients may require assistance, which is encouraged. This may include wearing gloves or mittens while sleeping (as a reminder), having family members participate in deterring scratching, or using behavioral modification techniques. Thomas Jefferson, who suffered from LSC, was known to pinch his skin and count to 10 before scratching.

Application of topical agents, such as steroids and immunomodulators, can help relieve the pruritus and plaque of LSC. Capsaicin, UV light, and emollients are common adjuvants. Topical formulations containing camphor and menthol provide benefit because they act on the cold-sensitive A nerve fibers, while phenol, pramoxine, and lidocaine deliver an anesthetic effect.1 Our patient was advised to continue topical agents to decrease inflammation and allay the itch sensation.

Systemic treatments include antihistamines, such as diphenhydramine. Oral antianxiety medications and sedatives may be considered in certain patients. Systemic steroids also have been used to treat acute pruritus, but they cannot be used on a continual basis for this condition. Our patient chose to continue using topical measures and was planning to pursue behavioral modification techniques.

Dr. Burkhart is clinical professor of dermatology at the Medical College of Ohio in Sylvania.
    

Reference

1. Burkhart CG, Burkhart HR. Contact irritant dermatitis and anti-pruritic agents: the need to address the itch. J Drugs Dermatol. 2003;2:143-146.ÿ