Background: Psoriatic lesions are characterized by induration, scaling and erythema. Erythema is a result of inflammation and increased microvascular blood flow. Anthralin is the strongest topical antipsoriatic drug that causes clearing of psoriatic lesions and temporary remission.
Objective: The objective evaluation of skin perfusion might be a suitable way to gain a better insight in the pathophysiological process of this disease and to evaluate the response to antipsoriatic anthralin therapy.
Methods: We evaluated 21 psoriatic lesions (plaques, patches and pinpoint lesions) including 4 lesions in remission with anthralin induced erythema and 4 controls of healthy, uninvolved skin. We performed the measurements with a combined fluorescence and remission imaging (FRIS). The FRIS sensor is coupled with a touch screen industrial computer. The equipment consists of a white-light halogen lamp (20 W), two VIS-spectrometer modules (Zeiss) for remission detection and references. Imaging is realized by CCD-colour camera module and white light ring-lighting. Fluorescence emission was realized using an ultraviolet LED with a wavelength of 370 nm. The fluorescence detector is a highly sensitive MCS CCD (Zeiss) with an integration time of 2.5 sec.
Results: Spectral remission of psoriatic skin is characterized by a pronounced decrease (60-80%) of the haemoglobin double-peak compared to uninvolved skin. The NADH-fluorescence is diminished in lesional psoriatic skin including anthralin-treated areas with clinical remission.
Conclusions: Vascular perfusion is increased in psoriatic lesions as demonstrated by remission spectroscopy. NADH-fluorescence is reduced in lesional psoriatic skin and in anthralin-induced erythema. FRIS is a suitable tool for objective evaluation of the cutaneous response to antipsoriatic treatment.