The role of infrared thermography in evaluation of proliferative infantile hemangiomas. Results of a pilot study

study Infantile hemangiomas (IH) are the most common tumors of infancy. They are clinically heterogeneous, making it difficult to adequately quantify the size/extent, monitor progression over time, and more importantly predict ongoing proliferation. Typically, the proliferative phase manifests by rapid increase in size of the lesion and increased local temperature. To date, objective methods of assessing proliferation and response to treatment are very limited. Visual analog scales (VAS) and hemispheric size estimates correlate strongly with clinical observations of growth and regression but are subject to intraand interpersonal variations. As clinicians, we rely on subjective indicators of proliferation and involution of IHs such as change in size and color, and surface temperature using dorsum of the hand (rapidly proliferating lesions are hot, while stationary ones have normal skin temperature when compared to the non-affected side). Infrared thermography is used for measurement of local temperature differences and has been shown to be a safe and useful method to evaluate thermal state-related pathologies, such as vascular malformations, IH, burns, digital reimplantation, and extremity thrombosis. It has also been used to assess inflammation in diabetic feet and joints in arthritis, disease activity in Paget’s disease, and in morphea plaques. It is non-invasive and easy to obtain, which is important when dealing with active infants. We conducted a pilot study to explore the use of infrared thermography in assessing and monitoring the proliferation and involution of patients with IHs that were systemically treated. This was a prospective pilot study in 10 patients with IH treated with a systemic beta-blocker. Local temperature was measured in the middle of the surface of the IH at baseline, weekly for one month and monthly until six months, using an infrared thermometer (TempTouch, Diabetica Solutions Inc., San Antonio, Tx, USA) and compared to the non-affected side. We did not include midline hemangiomas, as there would be no area to compare it with. Temperature differences between the affected and non-affected side were correlated with assessment of treatment response using a VAS, a 100 mm scale with three anchors: 100 = worsening, 0 = no change, + 100 = complete shrinkage of IH, where 5 mm represent 10% change in the size of IH. A blinded investigator performed the VAS evaluations by comparing standardized photos taken at each time point versus baseline. We enrolled 10 consecutive patients (six males) at a mean age of 4.1 (SD = 2.23) months. The IH were located on the periocular region (five of 10), nose (two of 10), perioral region (two of 10), and submandibular area (one of 10). All IH had a deep component, with six of 10 being mixed (superficial and deep). Over the study period, the median temperature difference decreased from 2.5 °F (IQR: 1–5) to 0.2 °F (IQR: 0.2 to 0.4), P = 0.001. The shrinkage in the IH size compared to baseline changed from 40% (IQR: 33–56) at week 1 to 97% (IQR: 96–100) at six months as assessed by VAS (Fig. 1). There was an overall inverse correlation between the temperature differences and shrinking of the hemangioma (ICC; 0.44 [95% CI: 0.63; 0.19]). Previous studies investigating thermography as a marker for disease activity have found a direct correlation between increased temperature and activity. The increased temperature is due to increased blood flow and heat conduction through the skin. A previous study reported a temperature decrease of 1.5 0.3 °C in resolved IH and used this differential to make decisions for treatment. Our study showed an inverse correlation between size and temperature of hemangiomas undergoing regression, thus indicating that temperature is a useful marker of their activity. According to these findings, temperature could be a safe, easy, and useful tool to measure therapeutic response as well, as there are so many variations in each individual’s response to current treatments. Theoretically, this method could be used in all hemangiomas regardless of their location or type (deep or superficial). Further evaluation is needed to assess validity, responsiveness, and reproducibility.