Lichen ruber planus is a chronic inflammatory skin disease that affects the skin, nails, scalp, and mucous membranes. The condition is characterized by small, itchy, purple-colored bumps on the skin that may be flat or raised. Lichen ruber planus is also known as lichen planus, a term derived from the Latin word for tree moss, "lichen." Other synonyms for lichen ruber planus include lichenoid dermatitis, lichenoid papules, and lichenoid rash. The condition can be triggered by a range of factors, including stress, infections, medications, and environmental exposures. It is typically treated with topical or oral medications aimed at reducing inflammation and relieving symptoms.