Histological study on the treatment of vascular malformations resistant to pulsed dye laser

The pulsed dye laser (PDL) is recognized both as an effective treatment for vascular malformations and the as first treatment of choice for these lesions. However, PDL irradiation has poor efficacy in some patients, particularly the elderly. The present study histologically assessed such patients to try to elucidate the reason.

A pulsed dye laser was used in 3 subjects in whom previous laser treatment was ineffective. Three-millimeter punch biopsies were obtained before laser treatment, 1 week and 3 months after the laser treatment. Each specimen was stained with toluidine blue and examined under light microscopy followed by electron microscopy with oolong tea extract (OTE) staining.

Microscopy revealed an increase in the vasculature at baseline and an increased number of dermal fibroblasts. One week post-irradiation, inflammatory cell infiltration was observed together with extensive interstitial perivascular edema. At 1 week and 3 months after laser irradiation, normal structures were observed for both blood vessels and capillary endothelial cells. Mild changes were noted in other interstitial features, but findings obtained 3 months after irradiation were almost similar to those before irradiation.

The lower efficacy of PDL treatment in the elderly was possibly due to the markedly low amount of red blood cells in our subjects' blood vessels, a major chromophore for the PDL, was markedly low. It is possible that age-related denaturation of dermal matrix collagen plays some role in maintaining the vasculature in the interstitium with edema, and inflammatory cell infiltration could lead to the cellular release of some cytokines which favor reconstruction of the vasculature.