Capillary vascular malformation response to increased ambient temperature is dependent upon anatomical location

It has been documented that capillary malformations (CMs) located on the limbs tend to respond less well to laser treatment than those sited on the head and neck. However, there is little evidence available to explain this observation.

To investigate potential differences between CMs located on the head and neck with those on the limbs, by comparing their response to increasing ambient temperature.

Fifteen previously untreated subjects with CMs were compared as the ambient temperature was increased from 20 degrees C to 28 degrees C. These included 10 with head and neck CMs and 5 with limb CMs. The following measurements were taken at 2 degrees C intervals: cutaneous blood flow, capillary diameter, density and depth, CM color, skin and core temperatures.

There were no statistically significant differences in mean capillary depth, diameter, density, or CM color between groups. Cutaneous blood flow increased with ambient temperature in the head and neck CMs (P = 0.009) and was significantly higher than that in the limb CMs at all temperatures (P < 0.001), while the limb CMs did not demonstrate any increase in cutaneous blood flow with temperature.

These results suggest a possible reason for the poorer response to laser treatment seen in limb CMs: since cutaneous blood flow is a product of the blood flow velocity and hemoglobin concentration, malformations with lower blood perfusion would have less chromophore available and therefore be less suitable for laser destruction.