Pilot study of dual-wavelength (532 and 633 nm) laser Doppler imaging and infrared thermography of morphoea

Summary Background Little is known about the pathophysiology of localized scleroderma (skin fibrosis, also termed ‘morphoea’), although it is likely that microvascular dysfunction is a contributing factor. Objectives Our aim was to investigate different components of blood flow in morphoea using infrared thermography and dual‐wavelength laser Doppler imaging (LDI). Methods Eight plaques of morphoea (in eight patients) were studied. Skin temperature and blood flow were assessed in both affected (within plaque) and adjacent unaffected (perilesional) skin. Results Skin temperature (representing blood flow) was higher in all areas of morphoea when compared with uninvolved skin. Perfusion within the plaques was found to be increased, when compared with uninvolved skin; in all cases as imaged by red wavelength (633 nm) LDI (representing blood flow through large, thermoregulatory vessels) and in six of eight cases by green wavelength (532 nm) LDI (representing nutritive capillary blood flow). The median (range) skin temperature difference between plaque and perilesional skin was 1·1 (0·7–2·2) °C and the median (range) ratios of plaque/perilesional perfusion as measured by red and green wavelength LDI were 1·3 (1·1–1·9) and 1·1 (0·8–1·5) arbitrary perfusion units, respectively. Conclusions Microvascular perfusion is increased within morphoea plaques and the increased response detected by both thermography and red wavelength LDI, as compared with green wavelength LDI, suggests that the increase in perfusion is more marked in deeper, larger, rather than in superficial, smaller vessels.