Background.  Haemangioma of infancy (HOI) is the most frequently occurring benign tumour of infancy. A good, reliable and objective scoring system for haemangioma activity is not yet available.

Aim.  We have developed a simple system called the Haemangioma Activity Score (HAS) for scoring the (disease) proliferative activity of haemangiomas. The current study was undertaken to validate this system.

Methods.  We validated the HAS in a comparative study of photographs taken during consultations from 2000 until 2008 (n = 78). Agreement between three observers was assessed at two different time points (t0 and t1) with a minimum interval of 6 months between them, using interclass correlation coefficients (ICC).

Results.  Agreement between observers was good. The average ICC of the HAS at t0 and t1 was 0.72 and 0.76, respectively. The average ICC of the HAS for the changes from baseline (HAS at t0 minus HAS at t1) was 0.69.

Conclusions.  We conclude that the HAS is a good system for scoring the proliferative activity of haemangiomas, and believe it to be useful in future investigations. The number of studies comparing different therapies for treating haemangiomas is steadily increasing, and the HAS (before and after treatment) may provide a valuable scoring system for evaluating such therapies.