This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: G.I.T., Subject name: Pathology
Aphthous ulcers known as 
Select and explain. 
A. Canker sores, B. Marjolin's ulcer, C. Curling's ulcer, D. Cushing ulcers
A: Canker sores
Answer: A: Canker sores 
Explanation: (Canker sores) (554,114, 211, 564, HM) (580- Basic pathology 8th)* Aphthous ulcers (Canker sores) - Commonest form of painful oral ulcers* In shock due to burns, acute stress ulcers of the stomach or duodenum may occurs and are known as Curling's ulcer* Squamous cell carcinoma developing in an old bum scar (Marjolin's ulcer)* Intra cranial lesion e.g. Head injury (Cushing ulcers developing from hyper acidity following vagal stimulation)