Onychophosis is a localized or diffuse hyperkeratotic tissue that develops on the lateral or proximal nail

Nail (anatomy)

A nail is a horn-like envelope covering the dorsal aspect of the terminal phalanges of fingers and toes in humans, most non-human primates, and a few other mammals. Nails are similar to claws, which are found on numerous other animals....

folds, within the space between the nailfolds and the nail plate

Nail plate

The nail plate is the hard and translucent portion of the nail, composed of keratin.- See also :* Runner's toe, repetitive injury seen in runners...

, 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 toe

Toe

Toes are the digits of the foot of a tetrapod. Animal species such as cats that walk on their toes are described as being digitigrade. Humans, and other animals that walk on the soles of their feet, are described as being plantigrade; unguligrade animals are those that walk on hooves at the tips of...

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