Lichen ruber planus – colloquially called nodular lichen – (Greek λειχήν leichén’ “lichen”; Latin ruber, “red-colored”; Latin planus, “flat”; synonyms: lichen planus; lichen ruber; ICD-10-GM L43.-: Lichen ruber planus (excl. Lichen pilaris)) describes a non-contagious (non-infectious), chronic inflammatory disease of the skin and/or mucous membranes.
The disease is characterized by a lichenoid tissue reaction. Flat, mostly polygonal, reddish-purple papules (nodules) or plaques (extensive or plate-like proliferation of substances on the skin) with sharp borders are seen. The papules may initially be centrally dented.
Lichen ruber planus is the most common idiopathic skin disease (disease of unknown cause) worldwide.
Lichen ruber planus can be subdivided according to the pattern of distribution (see symptoms below).
Sex ratio: Women seem to be affected slightly more often than men.
Frequency peak: The disease occurs predominantly in adults from the 3rd to the 6th decade of life. The disease rarely occurs in children (approximately 1-4% of cases).
The prevalence (disease incidence) is between 0.2-1.0% (adult population).
Course and prognosis: Lichen ruber planus is subacute (less severe) to chronic. The reddish-purple papules (nodules) are almost always itchy, sometimes intensely so. Characteristic is a whitish reticular striation on the surface of the papules and also on the mucosa (“Wickham striation”). The skin manifestations are found on the mucous membranes (25-70% of cases), often on the skin and mucous membranes (20%), and less frequently isolated on the skin (10%). They often occur symmetrically on the extremities, especially on the flexor sides. Scratching exacerbates lichen ruber planus and leads to recurrence of papules on previously healthy skin (Köbner effect). 25% of patients have isolated lichen ruber planus of the mucosa. Involvement of the nails (10% of cases) and hair typically results in nail dystrophy and scarring of irreversible alopecia (hair loss), respectively.The duration of disease without treatment is approximately 8 to 24 months (1 month to 10 years). The disease usually leaves a temporary brownish hyperpigmentation (increased coloration of the skin) on the affected areas of the skin.The disease tends to recur even after years (recurrence of the disease).
