BACKGROUND Acute phlegmonous esophagogastritis is a life-threatening disease that may be combined with serious complications. We present the classical radiological and endoscopic features and treatment strategy of a middle-aged female patient suffering from acute phlegmonous esophagogastritis complicated with hypopharyngeal abscess, esophageal perforation, mediastinitis, and empyema. CASE REPORT A 60-year-old Taiwanese female presented at our hospital due to fever, fatigue, painful swallowing, and vague chest pain for 5 days. She had a past history of uncontrolled type 2 diabetes mellitus. On physical examination, general weakness, chest pain, odynophagia, and a fever up to 38.9°C were found. Positive laboratory findings included leukocytosis (leukocyte count of 14.58×10³/μL, neutrophils 76.8%) and serum glucose 348 mg/dL (HbA1c 11.3%). A diagnosis of acute phlegmonous esophagogastritis with hypopharyngeal abscess was made based on typical computed tomography image features and clinical signs of infection. The patient received empirical antibiotic therapy initially; however, esophageal perforation with mediastinitis and empyema developed after admission. Emergency surgery with drainage and debridement was performed and antibiotics were administered. She was discharged in a stable condition on the 56th day of hospitalization. Six months later, a delayed esophageal reconstruction was performed. The patient has performed well for 9 months to date since the initial diagnosis. CONCLUSIONS Acute phlegmonous esophagogastritis complicated with hypopharyngeal abscess and esophageal perforation is extremely rare, and requires immediate medical attention. This report serves to remind physicians of this rare entity and the potential complications that may manifest with acute phlegmonous esophagogastritis.