Dorsal Pancreatic Agenesis Associated With New-Onset Diabetes Mellitus and Acute Pancreatitis in an 18-Year-Old Man: A Case Report.

Dorsal pancreatic agenesis (DPA) is a rare congenital disorder resulting from failure of development of the dorsal pancreatic bud. Complete DPA implies absence of the pancreatic neck, body, and tail and can be associated with both diabetes mellitus and pancreatitis. The patient was an 18-year-old man admitted with a history of epigastric pain, nausea, vomiting, polyuria, polydipsia, and unintentional weight loss of 4 kg over 8 weeks. The lab investigations included elevated serum glucose (412 mg/dL), urine ketones 3+, venous pH 7.31, bicarbonate 17.2 mEq/L, anion gap 14.8 mEq/L, lipase 486 U/L, amylase 312 U/L, consistent with hyperglycemic ketosis and metabolic acidosis, treated as mild DKA. The contrast-enhanced computed tomography (CT) study was read in real time by an abdominal radiologist and demonstrated the absence of the pancreatic neck, body, and tail, increased size of the head of the pancreas, a positive dependent-stomach sign, and mild pancreatic inflammation without necrosis and fluid collections. MRCP done 8 weeks later confirmed a normal ventral pancreatic duct and absence of dorsal pancreatic duct, consistent with the diagnosis of complete DPA. Fasting C-peptide 12 weeks after presentation was found to be extremely low (0.31 ng/mL) and antibodies to GAD65, IA-2A, and ZnT8 negative. These findings decreased the likelihood of classic autoimmune type 1 diabetes, suggesting involvement of the underlying pancreatic pathology and the presence of severe insulin deficiency. However, negative antibody type 1 diabetes cannot be ruled out. DPA should be suspected in young patients with unexplained pancreatitis and insulin-deficient diabetes. Imaging is essential, and MRCP provides the most valuable ductal information. Classification of diabetes should not depend solely on age, ketosis, or insulin requirement when a major congenital abnormality of the pancreas is present.