Scoring the proliferative activity of haemangioma of infancy: the Haemangioma Activity Score (HAS) S. R. Janmohamed,*†‡ F. B. de Waard-van der Spek,†§ G. C. Madern,* P. C. J. de Laat,– W. C. J. Hop** and A. P. Oranje†‡†† *Department of Paediatric Surgery, Erasmus MC, University Medical Center, Rotterdam, the Netherlands; †KinderHaven, Havenziekenhuis, Rotterdam, the Netherlands; ‡Department of Paediatrics, Division of Paediatric Dermatology, Erasmus MC, University Medical Center, Rotterdam, the Netherlands; §Department of Dermatology and Venereology, Erasmus MC, University Medical Center, Rotterdam, the Netherlands; –Department of Paediatrics, Erasmus MC, University Medical Center, Rotterdam, the Netherlands; **Department of Biostatistics, Erasmus MC, University Medical Center, Rotterdam, the Netherlands; and ††Department of Dermatology, Maasstadziekenhuis, Rotterdam, the Netherlands doi:10.1111/j.1365-2230.2011.04080.x Summary 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 (t 0 and t 1 ) 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 t 0 and t 1 was 0.72 and 0.76, respectively. The average ICC of the HAS for the changes from baseline (HAS at t 0 minus HAS at t 1 ) was 0.69. Conclusions. We conclude that the HAS is a good system for scoring the prolifera- tive 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. Introduction Haemangioma of infancy (HOI) is the most frequently occurring benign tumour of infancy. 1 Its incidence is 10% in the general population, with a higher incidence (20–30%) in premature infants. HOI is 1.5–5 times more common in girls than in boys, and is located on the face in 60% of the cases. 1,2 The diagnosis is usually only based on clinical observation and history. 3 The term ‘haemangioma’ has often been used incorrectly for other types of vascular anomalies, thus to avoid confusion, the term ‘haemangioma of infancy’ is preferred. 4 The lesion becomes apparent in the first weeks of life and grows rapidly during months. After this prolifera- tive phase, there is a period of inactivity and subsequent involution. 5,6 An HOI may cause severe complications, generally because of extensive growth or location, leading to life-threatening or disabling complications Correspondence: Professor Arnold P. Oranje, Department of Paediatrics, Division of Paediatric Dermatology, Erasmus MC, Sophia’s Children Hospital, PO Box 2060, 3000 CB, Rotterdam, the Netherlands E-mail: a.oranje@inter.nl.net Conflict of interest: none declared. Accepted for publication 23 January 2011 Clinical dermatology • Original article CED Clinical and Experimental Dermatology Ó The Author(s) CED Ó 2011 British Association of Dermatologists • Clinical and Experimental Dermatology, 36, 715–723 715