[Lichen planus].

Lichen planus is an inflammatory disorder of the skin and/or mucosa. Immune dysregulation, infections, environmental and genetic factors play a role in its pathogenesis. Clinically, there are 6 important distinctive manifestations. The mucosal subtypes manifest inside the mouth, oesophagus, genitalia and - although less often - the nose, ear canal, tear duct and conjuctiva. The non-mucosal subtypes occur on the skin, scalp (hair follicles) and nails. Patients may suffer from several subtypes of lichen planus. Unfamiliarity with the different manifestations may lead to a delay in diagnosis and thus to insecurity and distress in patients. The advice to all healthcare providers is to ask patients with lichen planus about symptoms of all subtypes and clinically inspect the skin and mucosa, or to refer the patient to a dermatologist.