Idiopathic trachyonychia (twenty-nail dystrophy): a pathological study of 23 patients.

We report the clinical features and pathological findings in 23 patients with idiopathic trachyonychia (twenty-nail dystrophy). Clinically, the nail changes in the majority of patients consisted of the typical 'sandpapered' appearance, with a rough, lustreless nail plate. In some, however, the nail plate abnormality was less severe, with numerous small, superficial pits, which imparted a shiny appearance to the surface of the nail. Histology of nail biopsy specimens showed spongiotic changes in 19 patients, psoriasiform features in three, and features of lichen planus in one patient. The mean follow-up of these patients was 2 years, during which time none developed alopecia areata or mucocutaneous lesions. Idiopathic trachyonychia is therefore a consequence of several inflammatory disorders, which produce a disturbance of nail matrix kinetics. The course of the inflammation and the extent of the inflammatory process within the nail matrix produce two different patterns of nail plate surface abnormalities.