Fluorescence remission spectroscopy of psoriatic lesions and the effect of topical anthralin therapy

Abstract

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. 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. 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. 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. 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.