Epidermal Damage and Limited Coagulation Depth with the Flashlamp-Pumped Pulsed Dye Laser: A Histochemical Study

Abstract

To investigate vessel coagulation depth and tissue damage in therapy with the flashlamp-pumped pulsed dye laser (585 nm, 5 mm spot size, 450 microsecond pulse duration, 6-8 J/cm2), we used the nitroblue-tetrazolium chloride stain in 22 post-treatment biopsy specimens from patients with port wine stain. With this method, thermally damaged tissue can be easily differentiated from unchanged tissue to the level of single cells. The results showed that in superficial port wine stain vessels up to 150 microns in diameter, vessel coagulation was complete and selective without further dermal damage. With the increase of vessel diameter, strong superficial hemoglobin absorption led to only partial vessel-wall coagulation and, in some cases, to superficial dermal damage. Likewise, deeper vessels were not coagulated because of shadow effects by superficial vessel layers. Thus, the overall vessel-wall coagulation depth of the flashlamp-pumped dye laser was limited to a maximum of 0.65 mm (mean 0.37 mm). In addition, some degree of epidermal damage was present in most specimens, which significantly increased with epidermal melanin content and resulted in epidermal coagulation and blistering in pigmented skin. Our results explain the occurrence of crusting, hyperpigmentation, and hypopigmentation in therapy with the flashlamp-pumped dye laser and its limited effect on dark or hypertrophic port wine stains in adults featuring large vessel diameters or multiple vessel layers.

Skin pigmentation characterized by visible reflectance measurements

“…Epidermal damage induced by the FLPDL is known to increase with increasing melanin content, ie skin of darker colour. The damage is found to vary from elongation of basal keratinocytes and subepidermal microvesiculation, to subepidermal blistering at higher radiant energy fluences (7).…”

A Comparison of Acquired Port-wine Stain with Congenital Port-wine Stain Using an Image Analyzer

“…To demonstrate correlation between clinical features and therapeutic response, many investigations were done with no unanimity [10][11][12][13][14] . Histopathologic examinations of PWS have also been done to establish the relationship between pathologic parameters and therapeutic responses [7][8][9][15][16][17] . Hohenleutner et al 15 of a diameter up to 150μm were completely coagulated.…”

“…Histopathologic examinations of PWS have also been done to establish the relationship between pathologic parameters and therapeutic responses [7][8][9][15][16][17] . Hohenleutner et al 15 of a diameter up to 150μm were completely coagulated. With increasing vessel diameter, strong superficial hemoglobin absorption led only to partial vessel wall coagulation.…”

Treatment of Necrobiosis Lipoidica with 595 nm Pulsed Dye Laser - A Case Report

“…Generally, 10 to 30 ms are necessary prior to each laser pulse. This epidermal cooling minimizes risks of adverse effects, such as hyperpigmentation (23% without the cooling method), hypopigmentation, and scars [6,10].…”

“…All dye lasers permit treatment of port-wine stains, which are classic indications for the dye laser [6], while Necrobiosis Lipoidica is hardly ever treated [7,8]. Third generation *Address correspondence to this author at the Private Office of Dermatology, Residence V° Avenue, 14 Place des Grenadiers-Quartier Grouchy, 42000 Saint-Etienne, France; Tel: +33 47791 1346; Fax: ++33 47791 1348; E-mail: jean.loic.michel@wanadoo.fr dye lasers emit light with a wavelength of 595 nm, and offer best performance for treating Necrobiosis Lipoidica.…”