Trachonychia (meaning "rough nails") is a medical term encompassing a primary disorder of the nail unit that mainly develops as an idiopathic condition. A number of dermatologic, genetic, autoimmune and systemic diseases, however, have been linked with trachonychia. Two types are described: opaque (a more common form in which the nails are brittle, thin, and rough) or shiny trachonychia (superficial ridging and pitting being the main features). Clinical findings are crucial in making the diagnosis.
Trachonychia is a term denoting a type of nail disorder that primarily arises as an idiopathic disorder seen in individuals of all ages and gender   . However, a number of isolated reports have described a strong association of trachonychia ("rough nails") with various disorders of genetic, autoimmune, and infectious origin, most important being alopecia areata    . Two clinical subtypes are documented in the literature:
A comprehensive clinical approach is necessary in order to make the diagnosis of trachonychia. A detailed history, during which patients should be inquired about the onset of symptoms and their progression, is recommended as the first step . A thorough family history of skin disorders is essential; the close inspection of the nails, the skin, the mucosal tissues (the oral cavity) and the hair is perhaps the crucial component of the workup, in order to exclude other dermatologic disorders . Some studies have used the term "twenty-nail dystrophy" or TND as a synonym for trachonychia, indicating the involvement of all twenty nails in the body, but that not may be the case in all patients  . Whenever a sandpaper-like appearance of the nails is observed, clinical suspicion towards trachonychia must be raised. Although distinct signs (and the underlying cause that led to this phenomenon) are yet to be solidified, the diagnosis remains on clinical grounds , but nail clipping (with subsequent histopathologic examination) is a rather useful method to differentiate between onychomycosis and trachonychia, as both can have a similar clinical presentation . Spongiosis, nail epithelia containing exocytosed inflammatory cells, and signs of lichen planus are main features on histopathology  . A longitudinal nail biopsy or obtaining a sample of the nail matrix is somewhat contraindicated because of the invasiveness of the procedures and scarring .