Cutaneous blood flow in dermatomyositis and its association with disease severity

Abstract

Several studies using nailfold capillary microscopes have demonstrated capillary changes in patients with dermatomyositis (DM); however, no previous study has examined cutaneous blood flow in this disease. To determine cutaneous blood flow in involved and non-involved skin surfaces of patients with DM and to assess possible correlation with clinical measures of disease severity. Using a Laser Doppler perfusion imager, cutaneous blood flow was measured at six targeted sites of involved and apparently non-involved skin of 13 DM patients and the corresponding non-involved sites of 13 healthy controls. Overall disease severity of DM patients was determined by physician's global assessment (PGA), creatinine phosphokinase (CPK) levels, medical research council (MRC) scores, and the DM skin severity index (DSSI). Skin blood flow was significantly elevated in involved vs. non-involved skin of DM patients at all anatomic sites measured: periungual (P=0.001), knuckle (P=0.001), elbow (P=0.013), periorbital (P=0.015), chest (P=0.028), and back (P=0.001). Blood flow was also higher in apparently non-involved skin of DM patients vs. skin of healthy controls at all anatomic sites, although statistical significance was not achieved. A significant negative correlation was observed between the DSSI and blood flow in involved skin of the chest (P=0.003), back (P=0.002), and knuckle (P=0.026). DM is associated with significantly increased cutaneous blood flow, even at sites where no erythema is evident. This suggests significant involvement of the skin vasculature in this disease process.