Onychophosis is a localized or diffuse hyperkeratotic tissue that develops on the lateral or proximal nailfolds, within the space between the nailfolds and the nail plate, and is a common finding in the elderly. Onychophosis may involve the subungual area, as a direct result of repeated minor trauma, and most frequently affects the first and fifth toes.
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Onychophosis Wikipedia(Text) CC BY-SA