Psoriasis is a disorder of skin hyperproliferation that commonly involves the nail unit. Approximately 80%-90% of patients with psoriasis display nail manifestations at some point in their lifetime. The manifestations of psoriasis may be limited exclusively to the nails in up to 10% of patients. Nail psoriasis has a significant effect on quality of life and is associated with higher risk of severe skin disease. Furthermore, nail involvement with psoriasis is a risk factor for developing psoriatic arthritis.

The most common nail findings in psoriasis are pitting, nail plate yellowing, onycholysis, subungual hyperkeratosis, splinter hemorrhages, and "oil spots." Psoriasis may also involve the nail folds in the form of swelling and chronic paronychia. Toenail findings are less frequent than psoriatic changes in the fingernails. When they do occur, subungual hyperkeratosis and yellow discoloration of the nail plate are the predominant findings.

Pediatric patient considerations:
Nail psoriasis in children is associated with more severe disease in most studies. It may be more common in boys than girls. The prevalence of nail psoriasis in children is 15%-19%. Furthermore, psoriasis is believed to be the cause of 7%-40% of all nail dystrophies seen in children.