Pancreatic Cysts, Necrosis & Resection

Fluid collections after acute pancreatitis

Timing and necrosis. The revised Atlanta classification names a collection by two questions: did the attack cause necrosis, and has the collection been present for more than 4 weeks?

Pseudocysts and bleeding complications

What a pseudocyst is. Pancreatic juice enclosed by granulation and fibrous tissue rather than epithelium. It usually communicates with the duct, so fluid amylase is very high and CEA low. Patients have persistent epigastric pain, early satiety, or fullness weeks after an attack, sometimes with a lingering lipase elevation.

When and how to drain. Asymptomatic pseudocysts are followed with serial imaging regardless of size; the old "6 cm or 6 weeks" rule is obsolete. Drain for pain, gastric outlet or biliary obstruction, infection, hemorrhage, or enlargement, after the wall matures. EUS-guided cystgastrostomy or cystoduodenostomy is first-line; surgical cystgastrostomy or Roux-en-Y cystojejunostomy is the fallback. Percutaneous catheters suit infected or immature collections but can leave an external pancreatic fistula.

Never drain a cystic neoplasm into the stomach. If the pancreatitis history is weak or the cyst has septa, nodules, or an epithelial lining, obtain EUS with cyst-fluid analysis first.

Pseudoaneurysm. Enzymes erode an adjacent artery, most often the splenic, then the gastroduodenal and pancreaticoduodenal. Bleeding appears as sudden pain, a falling hemoglobin, a clot-filled enlarging pseudocyst, or GI bleeding through the ampulla (hemosuccus pancreaticus). CT angiography localizes it; coil embolization is first-line, surgery the backup.

Other complications. Splenic vein thrombosis produces left-sided (sinistral) portal hypertension with isolated gastric varices, cured by splenectomy if they bleed; rupture causes amylase-rich ascites or pleural effusion.

Necrotizing pancreatitis and infected necrosis

Sterile necrosis. Nonenhancing tissue on contrast CT defines necrosis; imaging in the first 72 hours can underestimate it. Management is fluids, early enteral nutrition, and organ support; prophylactic antibiotics are not recommended.

Infected necrosis. Suspect it in weeks 2–4 with fever, leukocytosis, new organ failure, or decline; gas within the collection is strong evidence, and aspiration for culture is rarely needed. Give a carbapenem (imipenem or meropenem) or a fluoroquinolone plus metronidazole, which penetrate necrotic tissue; stable patients may recover on antibiotics alone.

Evidence. In the PANTER trial the step-up approach reduced the combined rate of major complications or death versus primary open necrosectomy, and about a third of patients needed drainage alone.

Cystic neoplasms and cyst-fluid analysis

Approach. A cyst without a clear pancreatitis history is a neoplasm until proven otherwise; MRI/MRCP and EUS-FNA characterize it.

Serous and mucinous cystic tumors. Serous cystadenoma has glycogen-rich cuboidal cells and is linked to von Hippel-Lindau disease; resect only for symptoms or diagnostic doubt. Mucinous cystic neoplasm occurs almost only in women, and its ER/PR-positive ovarian-type stroma is diagnostic; fit patients undergo distal pancreatectomy, usually with splenectomy. By age, serous cystadenoma is the grandmother lesion, MCN the mother, and solid pseudopapillary neoplasm (low-grade malignant, resected) the daughter.

IPMN. Mucin-producing papillary tumors grow in the main duct, its branches, or both; mucin may ooze from a "fish-mouth" papilla. Main-duct involvement (duct ≥5 mm) carries the highest cancer risk: a duct ≥10 mm warrants resection, while 5 to 9 mm is a worrisome feature that goes to EUS. Branch-duct lesions are triaged by risk:

• High-risk stigmata → resect: jaundice with a head cyst, enhancing solid component ≥5 mm, main duct ≥10 mm.
• Worrisome features → EUS ± FNA: cyst ≥3 cm, nodule <5 mm, thick enhancing wall, main duct 5–9 mm, raised CA 19-9, cyst growth ≥2.5 mm/year, new-onset or worsening diabetes, pancreatitis (Kyoto 2023).
• Neither → MRI/MRCP surveillance, spaced by cyst size.

Cyst fluid. CEA above about 192 ng/mL marks a mucinous cyst (MCN or IPMN) but not malignancy. High amylase marks duct communication (pseudocyst, IPMN); below 250 U/L essentially excludes a pseudocyst. GNAS mutations favor IPMN.

Pancreatic adenocarcinoma: presentation and staging

Presentation. About two-thirds arise in the head and cause painless obstructive jaundice, pruritus, dark urine, pale stools, and weight loss. Courvoisier sign, a nontender palpable gallbladder in a jaundiced patient, reflects gradual malignant obstruction; gallstones leave a scarred, shrunken gallbladder instead. Body and tail tumors present late with epigastric pain boring to the back. New-onset diabetes in an older adult and migratory thrombophlebitis (Trousseau syndrome) are classic clues.

Risk factors. Smoking leads the modifiable risks; others are chronic pancreatitis, obesity, and germline syndromes (BRCA2, PALB2, Lynch, Peutz-Jeghers, CDKN2A-related familial atypical multiple mole melanoma). KRAS is mutated in more than 90% of tumors.

Imaging and tissue. Pancreatic-protocol CT (thin slices, arterial and portal venous phases) is the key diagnostic and staging study, defining contact with the SMA, celiac axis, common hepatic artery, SMV, and portal vein and detecting metastases. EUS-FNA is the preferred biopsy route; tissue is required before neoadjuvant therapy but not before resecting a typical resectable mass. CA 19-9 aids prognosis and follow-up but cannot screen or diagnose: biliary obstruction raises it, and Lewis antigen–negative patients cannot make it.

Pancreatic resection and palliation

Operations. Pancreaticoduodenectomy (Whipple) removes the pancreatic head, duodenum, distal common bile duct, and gallbladder, with or without the antrum, and is rebuilt with pancreaticojejunostomy, hepaticojejunostomy, and gastrojejunostomy. Body and tail cancers get distal pancreatectomy with splenectomy.

• Delayed gastric emptying is the most common complication: nasogastric decompression, erythromycin, and nutritional support after excluding a leak or abscess.
• Pancreatic fistula is drain amylase more than 3 times the upper normal serum level on or after day 3; most close with drainage and nutrition.
• Hemorrhage from a pseudoaneurysm may follow a small sentinel bleed and is treated with angiographic embolization.
• Late effects are exocrine insufficiency (enzyme replacement) and diabetes.

Palliation. Unresectable disease receives FOLFIRINOX or gemcitabine plus nab-paclitaxel, with metal biliary stents for jaundice, duodenal stents or gastrojejunostomy for outlet obstruction, and celiac plexus neurolysis for pain.

Skip routine preoperative biliary stenting when surgery is prompt; stent for cholangitis, severe pruritus, or neoadjuvant therapy.