Canker sores (aphthous stomatitis)

If you child sees a physician for her canker sores, doctors usually diagnose them based on a complete history and physical examination of your child. The lesions are unique and usually your child's physician can make a simple physical diagnosis. In addition, you child's physician may order the following tests to help confirm the diagnosis and rule out other causes for the ulcers:

• blood tests
• cultures of the lesions
• biopsy of the lesion - taking a small piece of tissue from the lesion and examining it microscopically