Lichen Planus

• Is a non infectious immunological mediated skin disorder.
• It is a disorder in which lymphocytes attack the epidermis.
• It can be associated with autoimmune disorders such alopecia areata, ulcerative colitis.

Aetiology.

• It is unknown.
• Drugs can cause it-streptomycin,chloroquine,methyldopa, phenothiazine.
• It has also been linked to ,bone marrow transplant,hepatitis B infection,exposure to colour film in colour film developers.

Clinical Features

• Typical itchy papules, demarcated by skin lines on the extremities especially the volar aspects.

• White streaky pattern on the surface of the papules (wickham’s striae) white network buccal mucosa, top surface of papule; characteristic of Lichen Planus - itchy papule.

• It occurs on joint flexures especially the wrists (diff scabies contactdermatitis) , genitals, inner thighs.

• Koebner’s phenomenon is also present.

• Neighbouring papules may join together to form plaques that resembles lichen growing on trees.

• White lacy plaques in the mouth.

Variants

1. Annular -area of central clearing.
2. Atrophy-in mucous membrane.
3. Bullous
4. Follicular
5. Hypertrophic -around the ankles.
6. Ulcerative-on soles and mucous membrane.

Prognosis

• It is a self - limiting disorder in which individual lesions lasts for months and the eruption as a whole tends to last for about a year.

• As lesions resolve, they become flatter, darker and leave discrete brown macules.

Complications

1. Nail and hair loss may be permanent.
2. Ulcerative form in the mouth may lead to squamous cell carcinoma. Z
3. Ulceration over bony prominences may be disabling.

Differential Diagnosis

1. Lichenoid drug reactions- antimalaria, NSAIDS, b-blockers.
2. Discoid lupus erythematous- wickhams’s striae or oral lesions are absent.
3. Oral candidiasis.
4. Gold and heavy metals reaction.

Investigations.

• Diagnosis is usually obvious clinically, but a biopsy can confirm the diagnosis if necessary.

• Histology→ hyperkeratosis, focal hypergranulosis, thickening of the epidermis (saw toothed appearance) Z ,separation between dermis and epidermis.

Treatment

1. Stop offending agent.
2. Potent topical corticosteroids-to relieve the symptoms & flatten the plaques.
3. UV radiation-reduce pruritus , help clear the lesions.
4. Systemic corticosteroids-prednisolone .
5. Anti-histamines → for sedation