Localized scratch dermatitis, also known as lichen simplex chronicus or neurodermatitis, is a chronic itchy skin condition. It is believed that their is a strong psychogenic cause to localized scratch dermatitis and contrary to common beliefs, it has not been linked to any allergies or allergic causes.
Lichen simplex chronicus or neurodermatitis has a characteristic appearance of thick, dark discoloration of the skin occurring in plaques and at times may be misdiagnosed as psoriasis vulgaris.
What Causes Localized Scratch Dermatitis?
Causes of Lichen Simplex Chronicus
As mentioned, localized scratch dermatitis appears to be due to psychogenic causes. This is often known as a nervous itch or scratching due to psychosomatic causes. The sensation of itching may actually be felt by the sufferer although this sensation is due to neural activity (nerve signal transmission) in the absence of any stimuli. It may also be associated with nervous or anxious persons and depression and stress may aggravate the itching. A nervous itch may also be seen is certain psychiatric disorders or mental disabilities.
The skin lesion seen in neurodermatitis or lichen simplex may occur as a result of chronic scratching rather than due to any pathological factors.
Localized scratch dermatitis can affect skin on any area of the body, including the skin around the anus or labia of the vagina.
It is more often seen on the arm, especially forearm and legs which can be easily reached or scratched, even in public.
What Does Localized Scratch Dermatitis (Lichen Simplex) Look Like?
Signs & Symptoms of Localized Scratch Dermatitis (Lichen Simplex, Neurodermatitis)
One of the most noticeable signs of localized scratch dermatitis is constant itching which may be noticed by others and even affect social interaction. The typical texture of the skin lesion is similar to psoriasis in that the skin is thickened forming clearly demarcated plaques. The skin lesions may vary in size and shape but usually appears as oval shaped skin lesions.
The skin is typically dry and scaling due to the constant scratching, rubbing and irritation of the skin by the sufferer. In severe cases, a staph infection of the skin may occur (Staphylococcal epidermidis infection) due to breaks or cuts in the skin often caused by the finger nails. A fungal infection of the skin may also occur depending on the site of the lesion. Persistent scratching and irritation of the skin eventually results in the lichenified skin plaques which is typically seen as a dark discoloration of the skin.
How is Localized Scratch Dermatitis (Lichen Simplex) Treated?
Treatment of Localized Scratch Dermatitis (Lichen Simplex, Neurodermatitis)
Since localized scratch dermatitis is not due to any allergy (immune mediated hypersensitivity), anti-histamines are not effective in providing palliative relief of the itching. Oral corticosteroids may be useful for reducing the skin inflammation or itching sensation. Hydrocortisone creams should be applied on the skin lesions, and an antimicrobial or antifungal cream may be necessary for any secondary skin infection.
In cases of anxiety or depression, anti-anxiety drugs and antidepressants may reduce the severity of the itching. In other psychiatric disorders, appropriate treatment may also help relieve the scratching.