Differential diagnosis of nail apparatus lesions in subungual exostosis

Background. Subungual exostosis is an overgrowth of bone and/or cartilage tissue in the area of the distal phalanx of the finger. The etiopathogenesis of the disease remains incompletely understood. It is believed that many exogenous and endogenous factors participate in the development of subungual exostosis. The epidemiology of the disease also remains incompletely understood with conflicting data on its gender and age characteristics. Most often, toes are affected. Despite the fact that subungual exostosis is a surgical and orthopedic pathology, the disease also has a negative impact on the condition of the nail apparatus and the nail in particular. Nail changes with this pathology are observed in approximately 10% of patients. Affecting the nail apparatus, subungual exostosis can change the shape and consistency (structure) of the nail plate, lead to the development of various onychodystrophies, which can significantly affect the timing of the correct diagnosis and further patient management. This circumstance is also aggravated by the often asymptomatic course of the disease, in which nail pathological changes may be the only clinical sign of damage to the bone/chondral structures. Nail lesions in subungual exostosis can imitate other onychopathies, including infectious diseases, nail tumors, or be the cause of other associated disorders, such as onychocryptosis. However, in most cases, nail changes in this pathology are nonspecific, which creates additional difficulties for clinicians in the framework of routine care. It should be noted that timely diagnosis and rational therapy of subungual exostosis are important in preventing the development of complications such as osteomyelitis and ulceration. This is especially important for patients with vascular and metabolic disorders.

Results. This article presents data on subungual exostosis and variants of nail lesions in this pathology. Particular attention is paid to the issue of differential diagnostics between nail lesions in subungual exostosis and other onychopathies, including various types of onychodystrophies, benign and malignant nail tumors, and other associated disorders. According to the authors, subungual exostosis and associated nail lesions is an important interdisciplinary problem that requires the active participation of both orthopedists and dermatologists. 

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