Venous malformations are due to defective assembly of the venous vasculature. Defined subsets are now recognized. Venous malformations are most often due to pathogenic variants in the TEK (Tie2) gene, but also PIK3CA. Lesions due to glomulin pathogenic variants (GVMs) can mimic venous malformation. Nodular VMs can be seen in KRIT1 mutated CCM patients.