Psoriasis

	Plaques of psoriasis are obvious around the nails. The onycholysis and orange discolouration between it and the normal nail clinch the diagnosis. However, nail changes often occur without obvious skin involvement other than the scalp.
	Psoriasis underneath and surrounding the nail interferes with nail growth such that it may thicken, and subsequently detach, from the underlying nail bed.
	Pitting is present producing a number of short horizontal lines. There is onycholysis distally (particularly on the right) which does not occur in alopecia areata.
	The distal part of both thumb nails have separated from the nail bed. Psoriasis is present at the posterior nail fold which reinforces the diagnosis, but the yellow margin between the normal pink nail and the onycholysis is rather characteristic of psoriasis as is the symmetry.
	The nail is thickened, discoloured and partially broken off by psoriasis involving the whole of the nail.
	The nails generally appear slightly yellow. There is onycholysis distally and the characteristic yellow brown discolouration intervening between it and the normal pink nail. The occasional pit is present. Psoriasis is also visible on the skin.