Prominent black esophagus, Wischnewsky spots, and black duodenum in a fatal hypothermia case with an underlying diabetic ketoacidosis.

Hypothermia can occur in patients with diabetic ketoacidosis (DKA), and these two conditions can exacerbate each other. Fatal hypothermia and DKA have overlapping features and findings such as Wischnewsky spots (WS), black esophagus, basal subnuclear vacuolization in the renal tubule, dehydration, and increased acetone levels. Therefore, it may be challenging to differentiate or clarify the context of these two conditions. Herein, we report a case of a 49-year-old man with type 1 diabetes who was found lying in his house in mid-winter. He experienced cardiopulmonary arrest 10 h after the initial discovery and died at the hospital. On autopsy, florid left cardiac blood was observed. Black discoloration of the distal part of the esophageal mucosa, widespread WS in the gastric mucosa, and black discoloration of the duodenal mucosa were observed. Histologically, neutrophil infiltration in the esophageal mucosa, neutrophil infiltration and bleeding in the gastric mucosa, basal subnuclear vacuolization and Armanni-Ebstein lesion in the renal tubule epithelium in the kidney, and hyalinization of the islets of Langerhans were observed in the pancreas. Blood acetone and β-hydroxybutyrate levels were 538 µg/mL and 8947 µmol/L, respectively. Glycated hemoglobin A1c and glucose levels were 16.2% and 883 mg/dL, respectively, while C-reactive protein level was 3.64 mg/dL. In conclusion, obnubilation due to DKA was assumed to be the underlying cause of hypothermia, and the combination of these two conditions led to the outcome of death. The concurrent presence of these conditions likely contributed to the conspicuous mucosal findings in the upper gastrointestinal tract.