Acute Esophageal Mucosal Lesion Mimicking Severe Reflux Esophagitis in Diabetic Ketoacidosis: A Diagnostic Pitfall

A 65-year-old man with type 2 diabetes presented with abdominal pain. Although he had no typical reflux symptoms such as heartburn or acid regurgitation, esophagogastroduodenoscopy (EGD) showed findings suggestive of reflux esophagitis, and proton pump inhibitor therapy was initiated. Two months later, he was admitted with intractable vomiting. EGD demonstrated diffuse circumferential mucosal injury without black discoloration, predominantly in the distal esophagus. These findings were interpreted as severe reflux esophagitis (Los Angeles grade D; RE-D). Symptoms improved with supportive care, glycemic control, and continued PPI therapy; follow-up EGD showed marked improvement. Six months later, he re-presented with identical symptoms and endoscopic findings. Laboratory testing confirmed diabetic ketoacidosis (DKA), with ketonuria, elevated total ketone bodies (2469 µmol/L), and high-anion gap metabolic acidosis (anion gap 17.2 mEq/L). The diagnosis was revised to DKA-associated acute esophageal mucosal lesion (AEML). He improved with fluid resuscitation and insulin therapy, and medication adherence was reinforced. Follow-up EGD showed complete healing without recurrence. AEML has been proposed as a spectrum that includes acute esophageal necrosis (AEN; “black esophagus”) and esophagitis without black-appearing mucosa. This case highlights a diagnostic pitfall in which DKA-associated AEML without black discoloration may be misattributed to severe reflux esophagitis. When the clinical presentation or endoscopic appearance is severe or atypical, clinicians should consider AEML and evaluate for underlying systemic precipitants.