Nail Involvement in Cutaneous Psoriasis or Psoriatic Arthritis: Ultrasound and Microscopic Correlation

Introduction Onychodystrophy is common in individuals with psoriasis and psoriatic arthritis and is frequently associated with disease severity. Objective The objective of this study is to correlate ultrasound findings with alterations in nail clippings from patients with psoriasis and psoriatic arthritis, with and without nail dystrophy. Method Transversal study involving 120 patients distributed into four groups (psoriasis with and without onychodystrophy, psoriatic arthritis with and without onychodystrophy). All patients underwent clinical, ultrasound and microscopic evaluations of the nails. Results Neither ultrasound nor nail clipping results alone were able to consistently differentiate patients with and without arthritis. Nail clipping evaluation showed greater nail plate thickness in patients with onychodystrophy ( p =0.006). The presence of neutrophils was correlated with higher values for affected body surface area ( p =0.0032) and PASI ( p =0.0032) and NAPSI ( p =0.008) scores, indicating a link between psoriasis severity and inflammation. Significant correlations were found between ultrasound and microscopic variables related to the nail plate: microscopic thickness was correlated with grayscale Doppler findings ( p =0.002) and nail bed thickness was measured by ultrasound ( p =0.012). The presence of neutrophils was associated with increased nail bed thickness ( p =0.005) and grayscale findings in the nail plate ( p =0.00001). For the first time, microscopic blurring of the nail transition zone was linked to greater thickness of the nail bed measured by ultrasound ( p =0.001) and increased color Doppler activity ( p =0.018). Conclusion This is the first investigation correlating microscopic and ultrasound alterations in the nails of individuals with psoriasis and psoriatic arthritis, contributing to better comprehension of the markers of severity and inflammation.