Ultrasound Characterization of Psoriasis of the Nails: A Case-Control Study.

High-frequency B-mode ultrasonography and Doppler study can reveal changes in nail anatomy and vascularization in patients with nail psoriasis (NPs). The primary objective of this study was to describe thumbnail ultrasound findings in a series of adult patients with psoriasis involving the thumbnail. It was decided to focus on the thumbnail as this is the largest finger nail and also the one most often affected in NPs. A nonprospective, multicenter, cross-sectional case-control study was performed in which hospitals in 4 Spanish provinces participated. The controls were consecutive healthy subjects with no clinical disorders of the thumbnail who attended the dermatology clinic. The 5 investigators performed a single ultrasound study of each patient with the same parameters: 18 MHz linear transducer (B mode), between 6.6 and 12.5 MHz in Doppler mode, pulse repetition frequency of 750 per second and wall filter of 3. The structure and thickness of the nail plate as well as the thickness of the nail bed (distance between the ventral lamina and the phalange) were assessed along 2 axes, and Doppler signal of the nail bed and matrix area was assessed using a semiquantitative scale (0-3). The nail bed was defined as the area located below the nail plate distal to the eponychium (cuticle) and the matrix area as the area located below the proximal fold that delimits proximally with the insertion of the extensor tendon of the thumb and distally with the nail bed. The statistical analyses were performed with the SPSS program, version 21.0, and statistical significance was set at 0.05. Seventy-nine participants were included, 36 cases and 43 controls. The mean age was 44 years, 75% were women, and the mean body mass index was 25 kg/m, with no significant differences between the 2 groups. In patients with psoriasis, the mean age of onset of NPs was 32 years, the mean PASI was 5, 19% were diagnosed with peripheral psoriatic arthritis (PsA) (n = 7), and 30% were taking systemic treatment for