IGF-2 and FLT-1/VEGF-R1 mRNA levels reveal distinctions and similarities between congenital and common infantile hemangioma

Common infantile hemangioma appears postnatally, grows rapidly, and regresses slowly. Two types of congenital vascular tumors present fully grown at birth and behave differently from infantile hemangioma. These rare congenital tumors have been designated rapidly involuting congenital hemangioma (RICH) and noninvoluting congenital hemangioma (NICH). RICH and NICH are similar in appearance, location, and size, and have some overlapping histologic features with infantile hemangioma. At a molecular level, neither expresses glucose transporter-1, a diagnostic marker of infantile hemangioma. To gain further insight into the molecular differences and similarities between congenital and common hemangioma, we analyzed expression of insulin-like growth factor-2, known to be highly expressed in infantile hemangioma and VEGF-receptors, by quantitative real-time PCR, in three RICH and five NICH specimens. We show that insulin-like growth factor-2 mRNA was expressed in both RICH and NICH, at a level comparable with that detected in common hemangioma over 4 y of age. In contrast, mRNA levels for membrane-associated fms-like tyrosine-kinase receptor, also known as VEGF receptor-1, were uniformly increased in congenital hemangiomas compared with proliferating or involuting phase common hemangioma. These results provide the first evidence of the molecular distinctions and similarities between congenital and postnatal hemangioma.