PIK3CA and deep vein thrombosis: Venous malformations can be isolated or more complex when PIK3CA is the gene involved and are regrouped then under the appellation PIK3CA-related disorders.11,12 Histological examination of venous malformations usually shows thin-walled vessels that are variably dilated, commonly display thrombosis and occasionally contain phleboliths in the lumen and hemosiderin interpositions in the wall.