All of the following nail changes are associated with psoriasis, EXCEPT:

Pterygium formation is seen in severe cases of lichen planus. Nail changes in Psoriasis includes: Pitting: It is the most frequent change. Subungual hyperkeratosis Onycholysis Thickening and yellowish discoloration of nail plate Oil spots 10% of patients with Lichen planus have nail changes. Thinning of nail plate along with discoloration and irregular longitudinal grooves and ridges is the commonest change. Pterygium formation is seen in severe cases. Ref: Illustrated Synopsis Of Dermatology & Sexually Transmitted Diseases By Khanna page 123.