Nail changes are seen in in 25%-55% of patients with systemic lupus erythematosus (SLE) and are considered nonspecific integumentary manifestations of systemic disease. Onycholysis, defined as detachment of the nail plate from the nail bed, is the most common nail abnormality in patients with SLE, followed by longitudinal ridging. Other nonspecific nail changes include nail pitting, transverse ridges, transverse leukonychia, diffuse blue-black pigmentation, longitudinal melanonychia, subungual hyperkeratosis, pincer nails, red lunulae, yellow nails, thin nail plates, and pterygium inversum unguis. The only prospective study of nail involvement in patients with SLE found an increased prevalence of Raynaud phenomenon and mucosal ulceration in patients with nail changes.

Patients typically show concurrent skin findings that are more specific for SLE, including malar erythema or discoid lesions. Treatment of SLE may lead to correction of specific nail abnormalities.

Patients with SLE frequently show abnormalities of the vasculature of the nail folds marked by periungual erythema, splinter hemorrhages, and nail fold infarcts. Nail fold capillaroscopy evaluation in patients with SLE has revealed abnormalities of the microvasculature in 20%-93% of patients that include tortuous, elongated, dilated capillary loops. These findings are not specific for SLE but may correlate with disease severity.