Capillary microscopy of the nailfold in psoriatic and rheumatoid arthritis.

The nailfold capillaries of 35 patients with psoriatic arthritis and 30 with rheumatoid arthritis were studied by capillary microscopy and the findings compared. Seventy healthy subjects served as controls. The pronounced subpapillary plexus visibility, greater number of vessels and their elongation are indicative of rheumatoid arthritis, while shorter, fewer capillaries and especially characteristic psoriatic capillaries, when present, suggest psoriatic arthritis. Sluggish blood flow, higher number of hemorrhages and higher subpappillary plexus visibility are common to both patient groups as opposed to the controls.