Diseases that need to be differentiated from peritonsillar abscess include: parapharyngeal abscess, pericoronitis of wisdom teeth, and malignant tumor of tonsil. 1. Differentiate with parapharyngeal abscess: parapharyngeal abscess is swelling and pain on the side of the pharynx and the angle of the jaw outside the neck, which is caused by inflammation and infection. However, there is no obvious lesion in the tonsil itself, and it can be identified by CT of the neck. 2. Differentiate from wisdom tooth pericoronitis: wisdom tooth pericoronitis is the appearance of wisdom teeth in the jaw, resulting in swelling and pain in the surrounding gums, accompanied by ulcers and pus, but the tonsils are normal. 3. Differentiate with malignant tumor of tonsil: malignant tumor of tonsil manifests itself as enlargement of one side of tonsil, with ulcers and cauliflower-like changes on the surface. Peritonsillar abscess is characterized by significant congestion and localized elevation of the tongue and palate arch on one side. It can be differentiated by pathologic biopsy. Peritonsillar abscesses should be diagnosed promptly through relevant imaging tests and treated correctly under the guidance of a doctor.