Ultrasound characterization of the nail bed in patients with systemic lupus erythematosus

Objective: To characterize the ultrasound findings of the nail plate and nail bed in systemic lupus erythematosus (SLE) and its association with nail dystrophy.

Methods: Thirty-two SLE patients, 36 patients with osteoarthritis (OA) and 20 healthy individuals were studied. High-frequency linear ultrasound was performed in nails of the second to fifth fingers in all participants. Disease activity (SLEDAI-2K index), accrued organ damage (SLICC/ACR index), autoantibody profile, and Raynaud’s phenomenon were also assessed in SLE patients.

Results: Nail bed thickness in SLE patients was higher than in healthy individuals (1.25 ± 0.31 mm vs 1.17 ± 0.29 mm; P = 0.01) but lower than in OA (1.39 ± 0.37 mm; P < 0.001), while nail plate thickness was similar among groups. Nail dystrophy was found more frequently in SLE and OA than in healthy individuals. SLE patients with nail dystrophy were older than their counterparts with no dystrophy (39.4 ± 10.4 years vs 27.8 ± 5.6 years; P = 0.004), although nail dystrophy showed no association with SLICC/ACR, SLEDAI-2K, nail bed vascularity, or autoantibodies.

Conclusions: Nail bed in SLE patients is thicker than in healthy individuals but thinner than in OA patients. Nail dystrophy in SLE is associated with advanced age, but not with accrued organ damage, disease activity, Raynaud’s phenomenon, or DIP synovitis assessed by ultrasound.

Keywords: Nail dystrophy; systemic lupus erythematosus; ultrasound.