is this a burst vein?

what is the probable cause of large purple unexplained bruises on legs

[aldunn72023]

blood vessel could have broken, you could have bumped in to something without knowing-people do this all the time.  If you are experiencing this alot, you should see a doctor.

[SassyLassie]

You could be deficient in the vitamin called "bio-flavonoids" these are relatives to Vitamin C and they are very important in helping to keep from bruising. Bruising is due to broken blood vessels, and the bio-flavonoids keep them strong.

If they get worse or start to hurt, then I would sure see a doctor.

[caregiver222]

There are many possibilities. Generally this is because blood is leaking, and the reasons for this can be complex. It could be an issue for a hematologist or for a vasular specialist.

It could be from a simple vitamin K deficiency, hindering clot formation.

This is an indication for a complete work-up from an M.D.

If blood is leaking in the legs there is the possibility it may leak somewhere else, such as the brain.