A 62-year-old woman undergoes distal gastrectomy with D2 lymphadenectomy for T3N2 gastric cancer of the antrum. Intraoperatively, the tumor is found to directly invade the pancreatic head. The surgeon performs an en bloc distal pancreatectomy along with splenectomy to achieve R0 resection. Postoperatively, the patient develops severe hyperglycemia (fasting glucose 320 mg/dL) and steatorrhea. What is the most likely cause of these complications?

Explanation

## Pathophysiology of Post-Pancreatectomy Complications **Key Point:** En bloc distal pancreatectomy for T3 gastric cancer with pancreatic invasion results in loss of both endocrine and exocrine pancreatic tissue, causing hyperglycemia and steatorrhea. ## Endocrine Dysfunction ### Mechanism of Hyperglycemia - **Distal pancreatectomy** removes the pancreatic body and tail, where ~70–80% of insulin-secreting beta cells are located. - The remaining pancreatic head produces insufficient insulin to maintain euglycemia. - Results in **post-pancreatectomy diabetes mellitus** (PPDM), which is often brittle and difficult to control. - Incidence: 20–50% after distal pancreatectomy, higher if >50% pancreas is resected. **Clinical Pearl:** PPDM differs from type 1 diabetes—it is a form of secondary diabetes with loss of both insulin and glucagon secretion, making it prone to hypoglycemic episodes. ## Exocrine Dysfunction ### Mechanism of Steatorrhea - **Distal pancreatectomy** removes acinar tissue responsible for enzyme secretion. - Loss of pancreatic lipase, amylase, and proteases → fat and protein malabsorption. - Results in **pancreatic insufficiency** with steatorrhea (>7 g fat/day in stool). - May also cause azotorrhea (protein malabsorption) and weight loss. **High-Yield:** Both endocrine AND exocrine dysfunction occur together post-distal pancreatectomy. The combination of hyperglycemia + steatorrhea is pathognomonic for pancreatic insufficiency. ## Why This Patient's Presentation Fits | Feature | Explanation | |---------|-------------| | Fasting glucose 320 mg/dL | Loss of beta cells in pancreatic body/tail → insulin deficiency | | Steatorrhea | Loss of acinar tissue → lipase deficiency → fat malabsorption | | Timing | Immediate postoperative period (not delayed as in dumping syndrome) | | Severity | En bloc distal pancreatectomy removes ~60–70% of pancreatic mass | **Mnemonic:** **PPDM** = **P**ancreatic **P**ancreatectomy **D**iabetes **M**ellitus — remember both endocrine (hyperglycemia) and exocrine (steatorrhea) loss. ## Management Considerations 1. **Insulin therapy** — often required immediately; may need high doses. 2. **Pancreatic enzyme replacement** — lipase, protease, amylase supplements with meals. 3. **Fat-soluble vitamin supplementation** — vitamins A, D, E, K (malabsorbed in steatorrhea). 4. **Dietary modification** — low-fat diet, frequent small meals.