A proposed subungual exostosis clinical classification and treatment plan.

Subungual exostosis is a slow-growing, benign outgrowth of normal bone under the nail that affects the nail unit. The most common location in the foot is the dorsal surface of the distal phalanx of the big toe. Clinically, it can appear in combination with a variety of nail disorders, masking the underlying bone condition, which is frequently unrecognized or misdiagnosed. A new classification system for these lesions is proposed on the basis of the clinical signs and symptoms present during examination and the associated disorders of the nail plate. Also, a therapeutic algorithm that describes surgical approaches to the different presentations of this disorder is presented.