Lichen simplex chronicus is a chronic dermatitis caused by repeated skin scratching and/or rubbing. Scratching or rubbing causes further itching and then further scratching and/or rubbing, creating a vicious circle (itch–scratch cycle). Diagnosis is by examination. Treatment is directed at the initial cause of the itch and includes education and behavioral techniques to prevent scratching and rubbing, topical corticosteroids, and antihistamines.
(See also Definition of Dermatitis.)
Etiology of Lichen Simplex Chronicus
Lichen simplex chronicus is thickened and leathery (lichenified) skin with variable scaling that arises secondary to repetitive scratching or rubbing.
Lichen simplex chronicus is not a primary process. Perceived pruritus in a specific area of skin (with or without underlying pathology) provokes rubbing and mechanical trauma, resulting in secondary lichenification and further pruritus.
Lichen simplex chronicus frequently occurs in people with anxiety disorders and nonspecific emotional stress. Patients with atopy or atopic dermatitis are particularly susceptible, given their predisposition to itch.
Lichen simplex chronicus of the scrotum or vulva is often caused by an itch signal initiated by sacral sensory neuron radiculopathy.
Pathophysiology of Lichen Simplex Chronicus
Starting with an initial itch signal (for which the reason is sometimes unclear), the patient reacts by repeatedly scratching and/or rubbing the skin. The underlying pathophysiology of lichen simplex chronicus is unknown but may involve alterations in the way the nervous system perceives and processes itchy sensations.
Symptoms and Signs of Lichen Simplex Chronicus
Lichen simplex chronicus is characterized by pruritic, dry, scaling, hyperpigmented, lichenified plaques (single or multiple) in irregular, oval, or angular shapes. It involves easily reached sites, most commonly the legs, arms, neck, upper trunk, and genital region. It does not occur in areas of the skin that the patient cannot reach, such as the mid back (unless patient uses a back-scratching tool).
Prurigo nodularis is a related condition, likely a more prominent manifestation. In this disorder, skin lesions (nodules) are thicker and typically multiple.
Diagnosis of Lichen Simplex Chronicus
Clinical evaluation
Diagnosis of lichen simplex chronicus is by examination. A fully developed plaque is often hyperpigmented with varying amounts of erythema that is well-demarcated and has exaggerated skin lines and a thickened and leathery appearance characteristic of lichenification.
Lichen planus is a main differential diagnosis, and a biopsy is sometimes needed to differentiate between the two.
Treatment of Lichen Simplex Chronicus
Treatment of the cause of the itch
Education and behavioral changes
Corticosteroids (most often topical but sometimes injected intralesionally)
Antihistamines
If a cause of the initial itch can be identified (eg, radiculopathy, ill-fitting shoes, atopy), it should be treated or addressed. Otherwise, the primary treatment of lichen simplex chronicus is patient education about the effects of scratching and rubbing.
Key Points
Starting with an initial itch, chronic scratching and/or rubbing causes further itching, creating a vicious circle.
Itchy, dry, scaling, hyperpigmented, lichenified plaques occur in irregular, oval, or angular shapes on the legs, arms, neck, upper trunk, and the genital area.
Diagnosis is clinical; a biopsy is rarely needed.
The cause of the initial itch, if identifiable, must be addressed.
Patients need to be educated about the vicious circle of scratching/rubbing and about how to avoid doing so repeatedly; topical corticosteroids and antihistamines help control the itching.
