The condition that it sounds like is called Localized Oral Purpura.
Blood blisters in the mouth are not uncommon in elderly people, yet the cause of such lesions is unclear. No bleeding tendency appears to underlie this condition. Corticosteroid inhalers may sometimes predispose someone to this. Blood blisters are seen in the mouth or pharynx, but mainly on the soft palate and occasionally on the lateral border of the tongue in elderly people. There is rapid onset, with breakdown of the blood blister in a day or two to a large round ulcer.
To be 100% certain about this diagnosis, you would need to visit an oral surgeon who would perform a biopsy.
There is no specific treatment for your condition. The blisters should be carefully burst. Topical analgesics may provide symptomatic relief if you have any discomfort.
The following are some potential causes of purpura.
1. Trauma and suction
2. Platelet disorders:
* Autoimmune thrombocytopenia
* Bone marrow disorders: aplasia, leukaemia
* Infectious mononucleosis
* HIV infection
4. Vascular disorders
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