Nail Psoriasis

Psoriasis can affect both the toenails and fingernails. Commonly it appears as pits in the nails of various size, shape, and depth. Sometimes the nails develop a yellowish color and become thick. The nails may crumble easily and be surrounded by inflammation. Another possible symptom is detachment of the nail from the nail bed. Psoriasis can affect the connective tissue that forms the nails. Pitting of the nails may be an early sign of nail psoriasis, although pitting can also occur in other diseases. Other signs of nail psoriasis include the appearance of dark spots resembling oil droplets on the nails, the build-up of flaky skin cells under the nails, and separation or loosening of the nails from their beds (onycholysis). One or more nails may be affected.

Psoriasis of the fingernails and toenails is common but can be very difficult to treat. The nails may start to separate from the nail bed. During this process, the nail becomes whitish in appearance. Sometimes it becomes so badly damaged that it starts to crumble.About 50 percent of persons with active psoriasis have psoriatic changes in fingernails and/or toenails.

In some instances psoriasis may occur only in the nails and nowhere else on the body. Psoriatic changes in nails range from mild to severe, generally reflecting the extent of psoriatic involvement of the nail plate, nail matrix (tissue from which the nail grows), nail bed (tissue under the nail), and skin at the base of the nail. Damage to the nail bed by the pustular type of psoriasis can result in loss of the nail.

Nail changes in psoriasis fall into general categories that may occur singly or all together:
1) The nail plate is deeply pitted, probably due to defects in nail growth caused by psoriasis.
2) The nail has a yellow to yellow-pink discoloration, probably due to psoriatic involvement of the nail bed.
3) White areas appear under the nail plate. These are air bubbles marking spots where the nail plate is becoming detached from the nail bed (onycholysis). There may be reddened skin around the nail.
4) The nail plate crumbles in yellowish patches (onychodystrophy), probably due to psoriatic involvement in the nail matrix.
5) The nail is entirely lost due to psoriatic involvement of the nail matrix and nail bed.

Psoriasis of the nails can resemble other conditions such as chronic infection or inflammation of the nail bed or nail fold. Psoriasis of the toenails can resemble chronic fungal infection of the nails.A person with psoriatic nails should avoid any injury—bumps, scrapes, etc.—that may trigger a worsening of psoriasis (Koebner’s phenomenon). About one-third of people with nail psoriasis may have a fungal infection, which, if treated, could help their nails to improve. Some treatments used for skin psoriasis also may improve the condition of the nails.