Nail psoriasis involvement is associated with significant physical and psychological consequences for a substantial number of psoriasis patients
- prevalence data for nail involvement in psoriasis vary between 10% and 55% (1)
- prevalence rises to 70%-80% in cases where joint involvement is also present
- may occur as an isolated psoriatic finding.
- clinical spectrum is very heterogeneous depending on involvement of the nail bed, matrix, or folds, and includes pitting, grooving, and stippling, as well as discoloration, leukonychia, and onychodystrophy ranging to onycholysis
- combined nail matrix and nail bed psoriasis can develop in cases of very severe inflammation, a possible consequence of which is the formation of only parakeratotic, crumbly material by the matrix and bed, a condition referred to as 'psoriatic crumbly nail '
- this finding constitutes a risk factor for secondary mycotic infections, which can occur in up to 27% of psoriasis patients
- nail psoriasis is associated with a prolonged duration of psoriasis itself and greater severity of skin and joint involvement, and may also be an indicator for the activity of psoriatic arthritis (1)
Commonly seen on fingernails than on toenails (2).
Common findings in nail psoriasis include (2):
- onycholysis - separation of distal nail bed; if recent, there is a dull area under the nail with a salmon pink rim; later nail may become discoloured brown/yellow
- pitting - small, pin-head sized, irregularly arranged; relatively large compared to alopecia areata
- there may be subungal hyperkeratosis
- oil drop sign - orange-yellow areas under the nail plate (2)
In association with more severe psoriasis:
- entire nail surface becomes roughened and discoloured
- occasionally, pustular changes at the ends of the digits and in the nail bed
Click here for example images of psoriatic involvement of nails