A rare genetic vascular anomaly with characteristics of severe blood vessel expansion most frequently within the craniofacial bones with painless bone enlargement usually of mandibula, maxilla and/or orbital, nasal and frontal bones. This typically results in facial asymmetry and contour deformation. Midline abnormalities, such as diastasis recti, supraumbilical raphe, and hiatus hernia, are commonly associated. Additional features reported include gingival bleeding, ectopic tooth eruption, exophthalmos and loss of vision, nausea, and vomiting. There is evidence the disease is caused by homozygous mutation in the ELMO2 gene on chromosome 20q13.