Immune response: A possible role in the pathophysiology of hemangioma.

Hemangioma is a distinct category of benign vascular tumors characterized by presentation within the first weeks of life, rapid growth during the first year and variable degree of spontaneous involution over a period of several years. Recent research reported that CD8+ T cells in hemangiomas, and the endothelia of hemangioma uniquely expressed leukocyte marker FCgammaRII and myeloid cell marker. Presence of high levels of indoleamine 2,3-dioxygenase in proliferating hemangiomas and significantly decreasing during involution was also confirmed. Topical application of imiquimod cream, an immune regulator, to proliferating hemangiomas apparently accelerated regression of the lesions. These findings suggest immune response may be involved in the pathogenesis of hemangioma. The endothelia of hemangioma may express various markers to escape the immune surveillance. An immune response may be one of the mechanisms for hemangioma regression. Strategies with systemically or locally applying immune regulator into the tumor may be an applicable way in accelerating the involution of hemangioma.