A 58-year-old man from Delhi presents with painless jaundice and pruritus for 3 weeks. He denies fever or weight loss. On examination, he has icterus and a palpable gallbladder. Abdominal ultrasound shows a dilated common bile duct (CBD) measuring 12 mm with an abrupt transition point at the pancreatic head. The gallbladder is distended but contains no stones. What is the most likely diagnosis?

Explanation

## Clinical Presentation & Key Findings **Key Point:** Painless jaundice with a palpable gallbladder (Courvoisier sign) and imaging evidence of CBD obstruction at the pancreatic head is pathognomonic for pancreatic head malignancy until proven otherwise. ## Imaging Interpretation The ultrasound findings are classic: - Dilated CBD (>10 mm is abnormal; >12 mm is significant) - **Abrupt transition point** at the pancreatic head — this is the critical clue - Distended but stone-free gallbladder (Courvoisier gallbladder) - No intrahepatic bile duct stones or stricture pattern ## Differential Diagnosis Logic | Feature | Pancreatic CA | Choledocholithiasis | PBC | Stricture | |---------|---------------|-------------------|-----|----------| | Courvoisier sign | **Yes** | Rare | No | No | | Abrupt CBD transition | **Yes** | Gradual/irregular | Progressive | Focal narrowing | | Stone visibility | No | **Yes, visible** | No | No | | Painless onset | **Yes, typical** | Usually painful | Insidious | Variable | | Gallbladder distension | **Yes** | Often contracted | No | No | **High-Yield:** The **Courvoisier sign** (palpable gallbladder + jaundice) occurs in pancreatic cancer because the duct obstruction is distal, allowing proximal dilation and gallbladder filling. In choledocholithiasis, the gallbladder is usually contracted from prior inflammation. ## Why This Is Pancreatic Cancer 1. **Painless jaundice** — classic presentation; stones typically cause pain 2. **Abrupt CBD transition** — suggests a mass at the head, not a stone or stricture 3. **Courvoisier sign** — highly specific for distal bile duct obstruction from malignancy 4. **No visible stone** — rules out lithiasis **Clinical Pearl:** Pancreatic head cancer accounts for ~70% of pancreatic malignancies and typically presents late (stage III–IV) because the retroperitoneal location delays symptoms until biliary obstruction occurs. ## Next Steps Confirm with **CT with contrast** (pancreatic protocol) to assess: - Tumor size and local invasion - Vascular involvement (superior mesenteric vessels, portal vein) - Metastatic disease - Resectability Then **MRCP or ERCP** for tissue diagnosis and therapeutic stent placement if unresectable.