Canker sore, also known as “purple tongue swelling”, is a condition in which a child is born with something in his throat and tongue that looks like a hanging canker sore. This disease can occur alone or in the course of other diseases. It is mainly due to fetal toxicity, heat from the lung and stomach, and fire and blood congestion in the heart meridian. The common symptom is mild external vomiting of the tongue, so what are the tests that need to be done when going to the hospital? 1, clinical physical examination: the child’s pharynx is congested, the uvula is swollen and obvious, white purulent secretions are visible on the surface, some of them break down to form superficial ulcers, often accompanied by fever, crying and reluctance to eat. 2, laboratory tests: blood routine usually has an increase in white blood cells, mainly neutrophils; C-reactive protein is significantly increased or strongly positive; ESR is accelerated; blood culture can be positive; pharyngeal secretion culture can find pathogens. Based on the clinical features of this disease, it should be differentiated from acute purulent tonsillitis. The child also has severe pain in the pubic pharynx and is afraid to swallow. The pain often radiates to the ear and is accompanied by chills and high fever. On examination, the palatine tonsils are congested and visibly swollen, and pus plugs are visible. It can often cause peripalatal tonsillar abscess, and sometimes causes complications such as rheumatoid arthritis, acute nephritis and myocarditis. Distinctions can be made based on the characteristics of the clinical lesions.