eMedicine Specialties > Dermatology > Reactive & Inflammatory Dermatoses

Lichen Simplex Chronicus

Author: Daniel J Hogan, MD, Clinical Professor of Internal Medicine (Dermatology), NOVA Southeastern University; Investigator, Hill Top Research, Florida Research Center
Coauthor(s): Stephen H Mason, MD, Assistant Professor of Dermatology, Medical College of Georgia; Siobahn M Bower, MD, Internal Medicine Resident, Creighton University
Contributor Information and Disclosures

Updated: Oct 10, 2008

Introduction

Background

Lichen simplex chronicus (LSC) is thickening of the skin with variable scaling that arises secondary to repetitive scratching or rubbing. Lichen simplex chronicus is not a primary process. Rather, a person senses pruritus in a specific area of skin (with or without underlying pathology) and causes mechanical trauma to the point of lichenification.

A proposed variant of lichen simplex chronicus is lichen amyloidosis. Lichen amyloidosis is described as lichen simplex chronicus in which the keratinocytes have necrosed and formed keratinocytic-derived amyloid in the dermis. The initial insult is pruritus with resultant amyloid formation, rather than the reverse.^1,2

Pathophysiology

Lichen simplex chronicus is found on the skin in regions accessible to scratching. Pruritus provokes rubbing that produces clinical lesions, but the underlying pathophysiology is unknown. Some skin types are more prone to lichenification, such as skin that tends toward eczematous conditions (ie, atopic dermatitis, atopic diathesis). A relationship likely exists between central and peripheral neural tissue and inflammatory cell products in the perception of itch and ensuing changes in lichen simplex chronicus. The possible interplay among primary lesions, psychic factors, and the intensity of pruritus additively influence the extent and severity of lichen simplex chronicus.

A small study looking at lichen simplex chronicus and the use of P-phenylenediamine (PPD)–containing hair dye showed clinically relevant improvement in symptoms after discontinuation of PPD exposure, thus providing a basis for the role of sensitization and contact dermatitis in the etiology of lichen simplex chronicus.

Frequency

International

Exact frequency in the general population is unknown. In one study, 12% of aging patients with pruritic skin had lichen simplex chronicus.

Mortality/Morbidity

No mortality occurs as a result of lichen simplex chronicus. Overall, pruritus of lichen simplex chronicus is mild to moderate, but paroxysms may occur that are relieved by moderate-to-severe rubbing and scratching. Pruritus is usually described as much worse during periods of inactivity, usually at bedtime and during the night. Touch and emotional stress also may provoke pruritus, which is relieved by moderate-to-severe rubbing and scratching.

• Lesions cause little direct morbidity; however, occasionally patients report decreased or interrupted sleep, which affects motor and mental functioning.
• Lichen simplex chronicus SC may become secondarily infected after excoriation.
• Lichen simplex chronicus is often visible enough to cause patients to seek treatment.

Race

No differences are reported in frequency among races, although prior authors claimed lichen simplex chronicus was more common in Asians and African Americans. The appearance of lesions on darker skin sometimes shows follicular prominence. Secondary pigmentary alterations are also more severe in individuals with darker skin.

Sex

Lichen simplex chronicus is observed more commonly in females than in males. Lichen nuchae is a form of lichen simplex that occurs on the midposterior neck and is observed almost exclusively in women.

Age

Lichen simplex chronicus occurs mostly in mid-to-late adulthood, with highest prevalence in persons aged 30-50 years.

Clinical

History

• Patients with lichen simplex chronicus usually describe stable pruritic plaques on one or more areas; however, thickening of the skin occurs on any location that the patient can reach, including the following:
  • Scalp
  • Nape of neck
  • Extensor forearms and elbows
  • Vulva and scrotum³
  • Upper medial thighs, knees, lower legs, and ankles
• Erythema is noted most in early lesions.
• Pruritus is described as worse when patients are still or quiet and as much less or nonexistent when patients are active.
• Pruritus is usually intermittent; the resultant scratching provides temporary relief.
• Patients may have a past medical history of a chronic skin condition or acute trauma. Patients with atopic dermatitis may have lichen simplex chronicus in areas of former atopic outbreaks. Sites of irritant or allergic contact dermatitis, insect bites, or other past minor skin trauma sometimes demonstrate pruritus and, subsequently, lichen simplex chronicus.
• Each palm-sized plaque may have 3 zones. A 2- to 3-cm wide peripheral zone that is barely thickened may have isolated papules. The middle zone has lenticular and hemispheric prurigo papules that may be excoriated. The central zone has the greatest thickening and pigmentary alteration.

Physical

• One or more slightly erythematous, scaly, well-demarcated, lichenified, firm, rough plaques with exaggerated skin lines are noted.
• Pigmentary changes (especially hyperpigmentation) are seen variably as in any dermatitic lesion.
• Rubbing plays a key role in lesion formation and is visualized variably by white scratch marks, erosion, and ulceration from deeper scratching.
• Lichen simplex chronicus is one of the hyperkeratotic processes from which a cutaneous horn may grow.⁴
• Patients may scratch lesions de novo when observed. Some patients may start scratching while discussing the itch or describing the lesions.

Causes

• Atopic dermatitis results in a higher probability of developing lichen simplex chronicus.
• Insect bites, scars (eg, traumatic, postherpetic/zoster⁵ ), acne keloidalis nuchae,⁶ xerosis, venous insufficiency, and asteatotic eczema are common factors.
• Psychological factors appear to play a role in the development or exacerbation of lichen simplex chronicus.⁷
  • Anxiety has been reported to be more prevalent in patients with lichen simplex chronicus.
  • Neurodermatitis is a term formerly used interchangeably with lichen simplex chronicus, suggesting a role of anxiety or obsession as part of the pathological process of developing lesions.
• Lithium has been linked to lichen simplex chronicus in one reported case. Lichen simplex chronicus was dependent on the administration of lithium as evidenced by the observation that the lichen simplex chronicus remitted when the medication was discontinued and recurred when it was restarted.⁸
• A small study looking at lichen simplex chronicus and the use of PPD-containing hair dye showed clinically relevant improvement in symptoms after discontinuation of PPD exposure, thus providing a basis for the role of sensitization and contact dermatitis in the etiology of lichen simplex chronicus.⁹
• Long-term exposure to street traffic exhaust has been associated with an increase in the frequency of childhood skin diseases, including lichen simplex chronicus.¹⁰
• Some reserve the diagnosis of lichen simplex for patients who have no known predisposing skin disorder. The term secondary lichenification has been used if the eruption is initiated by a primary dermatosis.

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