Parakeratosis pustulosa describes a deformed fingernail or toenail surrounded by red, often scaly skin. It usually affects the thumb or index fingernail of young children, but occasionally involves another digit including a toenail. It is three times more common in girls.
It often starts with reddening of the skin under the free margin of the thumb or index finger nail. The redness later extends down to the nail fold resulting in swelling and loss of the cuticle. Thickened skin pushes up and deforms the nail plate.
Parakeratosis pustulosa is not itchy, but it may be a little painful.
The cause is unclear.
What does an affected nail look like?
The following signs may be seen.
Subungualhyperkeratosis (skin thickening under the distal edge of the nail)
Onycholysis (lifting of the nail plate off the nail bed)
Onychomadesis (shedding of the nail plate)
Pitting
Transverse ridging
Ragged or absent cuticles
Red skin around the nail
Blisters on the fingertips
These signs make it hard to distinguish from other skin conditions such as psoriasis and atopic dermatitis so although common, it is often misdiagnosed.
