A benign aberrant localized growth of the CAPILLARY ENDOTHELIUM. Usually appear in the neonatal period and are characterized by rapid growth during the first year, endothelial hypercellularity, and increased numbers of MAST CELLS. They then undergo slow involution and are replaced by fibrofatty stroma. Germline mutations in the KDR and ANTXR1 genes, and somatic mutations in the FLT4 gene have been identified. OMIM: 602089
