The nature and significance of the transverse white band of human nails.

The nomenclature relating to structures at the distal part of the nail is confusing. A distal yellow line traversing the nail, described by Pinkus, has been relatively ignored in the literature and remains unnamed. Clinical and histological studies presented in this article show that this band is present in more than 90% of normal adult fingernails and represents the most proximal point of attachment of the fingertip stratum corneum to the nail plate. Therefore, it should be referred to as the onychocorneal band or junction. This region has distinctive histological features and is the first major barrier to material passing proximally beneath the nail plate. It is possible that abnormalities of this structure may result in onycholysis, pachyonychia congenita, and pterygium inversum unguis.