In combination with the season, the region, and the history of contact within the most recent week, the clinical cases with a sore throat and inseparable grayish white pseudomembrane at the nasopharynx that is bleeding after forceful swabbing should be diagnosed as diphtheria. In smear of tissues harvested from the margin of the pseudomembrane, gram-positive corynebacteria with metachromatic granules can be microscopically found, which defines the diagnosis.

CT scanning demonstrates swollen tonsil as well as soft tissue swelling of the uvula, soft palate, posterior wall of the pharynx, nasopharynx, and larynx. For the cases with secondary infection of other bacteria, the accompanying cervical and submandibular lymphadenectasis can be found.

For the cases with complication of bronchopneumonia, both chest X-ray and CT scanning demonstrate enhanced and blurry pulmonary markings and spots of shadows along with pulmonary markings in the middle and lower fields of both lungs. With the condition progressing, the spots of shadows may be fused into large flakes of parenchymal shadows.