Final answer:
A patient with a persistent canker sore typically does not require immediate referral to a western physician as canker sores usually heal on their own, while other conditions mentioned may signify more serious infections or health issues.
Step-by-step explanation:
Among the options provided, you would most likely not refer a patient with a persistent canker sore to a western physician immediately, as canker sores typically heal on their own without the need for professional medical treatment. Canker sores are not contagious and usually resolve within a week or two. They may be caused by factors such as stress, hormonal changes, or food allergies. However, other conditions mentioned, like a thick white coating on the tongue or a white coating on the buccal mucosa, can indicate an infection like oral candidiasis, especially in immune-compromised individuals. A purple lesion in the back of the throat could be a sign of a more serious condition and should be evaluated by a physician. When in doubt, it is best to err on the side of caution and consult a healthcare provider.