A subungual exostosis is a bony growth that pushes up the nail plate. This collision between the nail plate and the expanding exostosis is a painful one. Subungual exostoses often appear during adolescence and usually affect the hallux. Differential diagnoses of subungual growths include subungual exostosis, subungual verruca, granuloma pyogenicum, glomus tumor, and melanotic whitlow. Little attention has been paid to subungual exostoses in recent years. Seven cases are described.
Cohen HJ, Frank SB, Minkin W, Gibbs RC. Subungual Exostoses. Arch Dermatol. 1973;107(3):431-432. doi:10.1001/archderm.1973.01620180081026