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Background Recent studies revealed that immune and immune-mediated inflammatory events may contribute to the pathogenesis of haemangioma. As a modulator of immune responses, the allograft inflammatory factor-1 (AIF-1) is involved in immune dysfunction and macrophage activation. Objective To investigate the possible role of AIF-1 in the progression of haemangioma. Methods In a retrospective study of haemangiomas in the oral and facial regions, we assessed lesional immunoreactivities for AIF-1, CD68 and Ki67. Negative controls were similarly confirmed, including 24 pyogenic granulomas, 26 vascular malformations, five samples of normal skin, 10 squamous cell carcinomas of the tongue and three placentas. Immunostaining for each antigen in the haemangiomas was compared with control tissues. Results Out of all the samples, intense immunoreactivity for AIF-1 was detected in 17 of 19 (89%) haemangioma specimens, with a specific location in the endothelial cells. The intensity of AIF-1 immunostaining did not show remarkable difference among proliferating, involuting and involuted haemangiomas. CD68-positive endothelial cells were found in the neovessels of haemangiomas, as well as in pyogenic granulomas and squamous cell carcinoma. Conclusions The exclusive expression of AIF-1 on endothelial cells of haemangiomas suggests that it may play a significant role in the pathophysiology and progression of haemangiomas. AIF-1 can be used as an additional biomarker for infantile haemangiomas. CD68-positive cells participate in the neovessel formation during proliferative haemangioma and contribute to the promotion of haemangioma growth. [ABSTRACT FROM AUTHOR]