Longitudinal erythronychia with distal subungual keratosis: onychopapilloma of the nail bed and Bowen's disease.

We biopsied longitudinal erythronychia in 16 subjects, and found an onychopapilloma in 14 cases and Bowen's disease in the remaining two. Shared clinical features in addition to erythronychia (or sometimes an interrupted line made up of splinter haemorrhages) were typically a longitudinal marked ridge of the nail bed expanded at the distal nail bed as subungual keratosis, and associated localized onycholysis. The presentation of Bowen's disease in this pattern has not been previously reported. In all cases of onychopapilloma of the nail bed, acanthosis and papillomatosis were evident, and were associated with a keratogenous zone identical to the nail matrix. In addition, we found multinucleate giant cells in two onychopapillomas. We have therefore suggested that the term 'localized, distal, subungual keratosis with multinucleate cells' should be replaced by 'onychopapilloma' (nail-producing papilloma).