ABSTRACT
The clinical findings of nail psoriasis depend on the area of the nail apparatus affected by the inflammatory infiltrate—nail matrix or nail bed or periungual tissues. When the matrix is involved, the plate shows irregular pitting, thickening, and crumbling, and more rarely a red lunula is visible through the proximal portion. When the bed is involved, onycholysis, subungual keratosis, and splinter hemorrhages are typical signs. When the periungual tissues are involved, it is common to see paronychia with inflammation and scales. All these signs could present isolated or freely combined in the same patient and even in the same nail. Some of them are however not unique to psoriasis, and for this reason, the diagnosis is often delayed. Onychomycosis is frequently associated with further delaying of the diagnosis. Due to the relation that nail psoriasis has with psoriatic arthritis, great attention should be addressed to the nail signs that might reveal a possible joint involvement in order to early refer patients to a rheumatologist and even contributing to the prevention of arthritis. Pitting and, above all, onycholysis seem to occur more often in patients with arthritis compared to those without.
