A Study On Effects Of 532nm Continuous Laser Combined With Photodynamic Therapy And 595nm Pulsed Dye Laser On Chicken Comb Model Of Vascular Malformation

Background Nevus flammeus, also known as port wine stains (PWS), are a common congenital vasculopathy consisting of an abnormal network of capillaries in the upper dermis with an overlying normal epidermis. Pulsed dye laser (PDL) is currently still a’gold standard’for the treatment of PWS worldwide at a wavelength of 585 nm or 595 nm. With the development of photodynamic techniques, PDT was used for the treatment of PWS and obtained excellent therapeutic effect, thus it has become one of the best choices for treatment of PWS. At present, it mainly uses the method of intravenous injection of photosensitizer HMME for PDT. Fundamental researches showed that HMME presented characteristic absorption peaks at 401, 500,533,569,613 nm. Therefore, PDT for treatment of PWS currently chooses green light with slight penetrability which can be selectively absorbed by hemoglobin.Objective To explore the effects of 532 nm continuous laser combined with photodynamic therapy (PDT) and 595 nm pulsed dye laser (PDL) on chicken comb model of vascular malformation.Method 90 adult male chickens were divided into three groups randomly taking the one comb side as the treatment side while the other side as the self-control side. Group A:the 532 nm continuous laser combined with hematoporphyrin monomethyl ether photodynamic therapy (HMME-PDT) group. A single intravenous injection of HMME was administered to the chickens, and the treatment side of combs were irradiated with a 532 nm continuous laser once. Group B:the 595 nm pulsed dye laser (PDL) group. The treatment side of combs were irradiated with 595 nm PDL once. Group C:the control group. The combs were treated with neither photosensitizer nor irradiation.Result Compared with self-control side, part of the treated combs had blanched after HMME-PDT while histopathology showed an absence of erythrocytes and the vessel lumina were obliterated, leaving the normal overlying epidermis completely intact concomitantly with selective destruction of the capillaries in the target area and obvious reduction of vascular numbers (P<0.01). Part of the treated combs were completely ineffective (30%,9 cases), the total effective rate was 70%(21 cases), no case with scars. Most of the traeated combs had blanched after PDL while histopathology showed an absence of erythrocytes and the vessel lumina were obliterated, leaving the overlying epidermis with slight injury and scab concomitantly with destruction of the capillaries in the target area and obvious reduction of vascular numbers (P<0.01). The total effective rate was 93%(28 cases), two cases with scars. The combs of control group showed no change compared with self-control side (P>0.05).Conclusion In the chicken comb model, both 532 nm HMME-PDT and 595 nm PDL could damage capillaries in the superficial dermis of combs; compared with 595 nm PDL,532 nm HMME-PDT had smaller side effect; 532 nm HMME-PDT group had higher inefficiency rate compared with 595 nm PDL group but there was no significant difference in gross and histopathological results in both groups with better therapeutic effect ones (P>0.05).