We look at Lichen planus, the purple itchy skin rash triggered by the immune system.
By Dr Catherine Borysiewicz
If you have an unexplained purple itchy rash, you’d be forgiven for assuming the worst. However, it might be Lichen planus, an inflammatory skin condition. This type of non-infectious rash can affect the skin in most areas of the body, including the mouth and genitals.
Fortunately it usually clears up on its own within a few months. However, oral and genital Lichen planus may be more persistent, so always ask your GP for advice.
Dr Catherine Borysiewicz expert in skin cancer and general inflammatory dermatology and Consultant Dermatologist at the Cadogan Clinic looks at the causes, symptoms and treatment options for Lichen planus.
What is Lichen planus?
Lichen planus is an inflammatory condition affecting the skin and mucosal surfaces- the mouth and genital surfaces.
What causes Lichen planus?
Lichen planus is an autoimmune condition- so it occurs when your own immune system that is usually responsible for removing infections and keeping us healthy, starts to react against normal proteins within the skin and mucosa.
It can occur without a trigger, but in some cases it can be triggered by a reaction to medication or a viral infection.
Where does it occur?
The reaction can occur anywhere on the skin, hair follicles and nails, as well as mucosal surfaces inside mouth or genital areas. It can just affect small localised areas, or occasionally be more widespread.
What does Lichen planus look like?
In dermatology we refer to it has having ‘all the P’s’: purple, polygonal papules and plaques. The lesions on the skin can start as a spotty rash that is raised from the surface of the skin with a purplish or brown colour.
They can localise in areas of skin damage, such as scratch marks, or old scars- we call this phenomenon köbnerisation, and it helps dermatologists make the diagnosis. In the mouth it can create white streaks in the gums and cheeks and can cause sores or ulcers to form.
Common Lichen planus symptoms
Usually when the rash first appears it is very itchy and uncomfortable. It will peak, and then start to settle, leaving stains on the skin that will fade over time.
Lichen planus treatment
The symptoms of the rash usually trigger people to seek an appointment with their doctor or dermatologist.
✔️ Sometimes a biopsy and blood tests are performed to help diagnose the rash and look for possible triggers.
✔️ A topical steroid can settle the lesions and occasionally a course of steroid tablets may be needed.
✔️ Once the itching settles the post-inflammation staining in the skin can be helped with regular moisturiser use.