Can a vascular malformation cause a hard blanchable lesion thats 10mm length x 6mm width on hard palate near the midline of palate?

Probably not: Usually a hard bony lesion at the midline of your palate is a benign mass called a 'palatal torus'. They can also be found on the insides of the lower jaw by the tongue. If it has grown rapidly, or is painful, you may want to have it checked by your dental professional. Vascular lesions are usually soft and slightly moveable instead of hard and fixed. Either way, check with your dentist.

Tori: A hard lesion on the midline of the palate may be what is called a maxillary tori. It is a benign outgrowth of the bone. See you dentist or oral surgeon who will quickly be able to confirm this. Any swelling should be evaluated.