[Differences of spectral Doppler in psoriatic arthritis and onychomycosis]

To evaluate the use of the spectral Doppler (SDoppler) to quantify inflammatory activity and to detect nail echotextural differences in patients with psoriatic arthritis and onychomycosis.

Two patients, one with psoriatic arthritis but with no joint pain nor nail clinical change and the other with onychomycosis and rheumatoid arthritis were included. The gray scale ultrasound study, showed changes in the regular presence of echotexture at the nail insertion, thickening of the nail bed and loss of trilaminar nail pattern. The spectral Dopplerresistance index (RI), detects the inflammatory process in nail entheses.

Seven distal interphalangeal (DIP) joints in both patients were evaluated in two planes, getting nine RI. In the patient with psoriatic arthritis the author found: loss of normal trilaminar nail plate aspect, and nail beds and DIP joint capsules preserved. The spectral Doppler showed RI<1, with mean±SD=0.50±0.75 in the microcirculation at nail entheses, with characterization of a bone erosion in the third left DIP joint, with RI=0.38 and 0.63 in transverse and longitudinal planes, respectively. The patient with onychomycosis showed the following changes: hypoechogenicity at nail insertion; loss of nail shape, and spectral Doppler in nail entheses with RI>1, with mean±SD=1.71±0.98.

The use of ultrasound can detect changes in the nail beds in these diseases. Future studies will further characterize these changes.