Trachyonychia ("rough nails") is best considered a reaction or morphologic pattern with a variety of clinical presentations and etiologies. It may involve only 1 or as many as 20 nails (20-nail dystrophy). It can be a manifestation of lichen planus, psoriasis, alopecia areata, immunoglobulin A deficiency, atopic dermatitis, and ichthyosis vulgaris