A 58-year-old woman with a 20-year history of type 2 diabetes presents with progressive jaundice over 3 weeks, painless dark urine, and weight loss of 4 kg. She denies fever or abdominal pain. On examination, she is afebrile, icteric, with a palpable gallbladder (Courvoisier's sign positive) and no hepatomegaly. Laboratory investigations: total bilirubin 9.5 mg/dL (direct 8.1 mg/dL), ALT 185 U/L, AST 210 U/L, ALP 580 U/L, GGT 620 U/L. Abdominal ultrasound shows dilated intrahepatic ducts, dilated common bile duct (CBD 12 mm), and a hypoechoic lesion in the pancreatic head. What is the most likely diagnosis?

Explanation

## Clinical Diagnosis: Pancreatic Adenocarcinoma ### Pathognomonic Presentation **Key Point:** This is a textbook presentation of pancreatic head cancer: - **Painless progressive jaundice** (hallmark — jaundice is the first symptom, not pain) - **Courvoisier's sign positive** (palpable gallbladder with jaundice) — the gallbladder is distended because the tumor obstructs the CBD below the cystic duct entry - **Weight loss** (constitutional symptom of malignancy) - **Subacute onset** over weeks (not acute) - **Imaging findings**: hypoechoic pancreatic head lesion + dilated CBD + dilated intrahepatic ducts ### Why This Is Extrahepatic Cholestasis The **cholestatic pattern** (ALP >> ALT, ALP 580 vs ALT 185) with **dilated ducts** indicates obstruction **downstream of the hepatocyte** — i.e., in the biliary tree or pancreatic duct. The imaging shows the obstruction site: pancreatic head mass compressing the CBD. ### Courvoisier's Sign: Clinical Pearl **Clinical Pearl:** Courvoisier's sign (palpable gallbladder + jaundice) is **highly specific for pancreatic cancer** because: 1. The tumor obstructs the CBD at or below the ampulla 2. Bile backs up into the gallbladder, causing distension 3. In gallstone obstruction, the gallbladder is often **fibrosed and non-distensible** (Courvoisier's sign is negative) This sign alone should raise suspicion for pancreatic malignancy. ### Differential Diagnosis Table | Feature | Pancreatic Cancer | Acute Pancreatitis | Autoimmune Pancreatitis | Gallstone Obstruction | |---------|-------------------|-------------------|----------------------|----------------------| | **Onset** | Subacute (weeks) | Acute (hours–days) | Insidious (weeks–months) | Acute/colicky | | **Pain** | Absent or mild | Severe, epigastric | Mild, chronic | Colicky RUQ | | **Fever** | No | Yes | No | Yes (if cholangitis) | | **Courvoisier's sign** | **Positive** | Negative | Negative | Negative | | **Weight loss** | Yes | No | No | No | | **ALP >> ALT** | Yes | No | Yes | Yes | | **Imaging** | Hypoechoic mass in pancreas | Pancreatic edema/necrosis | Diffuse pancreatic enlargement | Stones in CBD | | **CA 19-9** | Elevated (>100) | Normal | Normal | Normal | **High-Yield:** **Painless jaundice + weight loss + Courvoisier's sign = Pancreatic cancer until proven otherwise.** ### Mechanism of Jaundice ```mermaid flowchart TD A[Pancreatic head adenocarcinoma]:::outcome --> B[Compression of CBD]:::action B --> C[Obstruction to bile flow]:::action C --> D[Backup of bile into liver]:::action D --> E[Direct hyperbilirubinemia]:::outcome D --> F[Dilated intrahepatic ducts]:::outcome D --> G[Dilated CBD > 6 mm]:::outcome E --> H[Dark urine, pale stools, jaundice]:::outcome ``` ### Next Diagnostic Steps 1. **CT abdomen/pelvis with contrast** (staging, assess resectability) 2. **CA 19-9 tumor marker** (prognostic; often >100 in pancreatic cancer) 3. **ERCP with stent placement** (biliary decompression if jaundice symptomatic) 4. **EUS-guided FNA** (tissue diagnosis if needed before surgery) [cite:Harrison 21e Ch 303; Robbins 10e Ch 19]