Primary intraosseous venous malformation is a rare, genetic vascular anomaly characterized by severe blood vessel expansion (most frequently within the craniofacial bones) with painless bone enlargement (usually of mandibule, maxilla and/or orbital, nasal, and frontal bones), typically resulting 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, loss of vision, nausea, and vomiting. The disease is MONDO_0011744 (primary intraosseous venous malformation). Also known as: intraosseous hemangioma, osseous venous malformation.