Lichen planus of the nails

**Definition:** Lichen planus of the nail most commonly presents as nail plate thinning with longitudinal grooving and ridging. Hyperpigmentation, subungual hyperkeratosis, onycholysis, and longitudinal melanonychia can also occur. Rarely, the matrix can be permanently destroyed with prominent pterygium formation. Lichen planus has been linked to childhood idiopathic nail atrophy and may overlap with twenty-nail dystrophy of childhood.