What Is Lichen Lichen Planus

Lichen planus is a common, distinct inflammatory disorder that affects the skin, mucous membranes, nails, and hair.

Lesions appear as symmetric, grouped, erythematous to violaceous, flattopped, polygonal papules.
Close inspection of the lesions with a hand lens and after application of mineral oil will reveal fine white lines (Wickham striae).

Etiology of the dermatosis is diverse and includes drugs, metals, and infections (especially hepatitis C), which result in alterations of cell mediated immunity.

Women are affected more often than men, and the typical age of onset is between 30 and 60. 

Treatment
Topical and systemic corticosteroids or cyclosporine.

Notes:

â–  Four Ps: purple, polygonal, pruritic, papules

â–  Cutaneous lesions: distributed typically on flexural aspects of arms and legs but may become generalized;
symptom is pruritis

â–  Oral lesions: Milkywhite reticulated papules, which may become erosive or ulcerate; symptom is pain