Cankers are indurated ulcers which, in most cases, are asymptomatic and often seen on the lips, oral mucosa, tongue, palate and posterior pharyngeal wall.
[scielo.br]
Haemophilus influenzae Moraxella catarrhalis Quinsy Staphylococcus aureus (rare) Syphilis (rare) Acute ulcerative gingivitis (Vincent angina infection) Viral Severe–moderate
[murtagh.mhmedical.com]
Acute pharyngitis may be catarrhal, purulent, or ulcerative, depending on the causative agent and the immune capacity of the affected individual.
[en.wikipedia.org]