Psoriatic nail changes in the form of pitting and hypertrophy are generally regarded as being quite resistant to topical treatment. In the present pilot study, it was found that topical application of 1% fluorouracil solution, without the use of occlusive bandages, produced apparent decrease of pitting and hypertrophy in 17 of 20 patients with psoriatic lesions of the fingernail. The treatment, which lasted six months, resulted in a 75% reduction of severity on the average.
Fredriksson T. Topically Applied Fluorouracil in the Treatment of Psoriatic Nails. Arch Dermatol. 1974;110(5):735-736. doi:10.1001/archderm.1974.01630110033006