A 52-year-old man from rural Maharashtra presents with a 3-week history of progressive jaundice, pale stools, and dark urine. He denies fever, abdominal pain, or recent weight loss. On examination, he is afebrile, icterus is present, and the abdomen is soft with no hepatomegaly or splenomegaly. Laboratory investigations show: total bilirubin 8.2 mg/dL (conjugated 6.8 mg/dL), ALT 45 U/L, AST 52 U/L, ALP 320 U/L, GGT 280 U/L. Ultrasound abdomen reveals dilated intrahepatic and extrahepatic bile ducts with a hypoechoic lesion at the pancreatic head. What is the most likely diagnosis?

Explanation

## Clinical Diagnosis: Pancreatic Adenocarcinoma ### Key Clinical Features **Key Point:** The combination of painless jaundice, progressive course, pale stools (acholia), dark urine, and imaging findings of a pancreatic head mass with biliary obstruction is pathognomonic for pancreatic cancer. ### Diagnostic Reasoning 1. **Pattern of Jaundice** - Conjugated (direct) hyperbilirubinemia predominates (6.8/8.2 mg/dL) - Indicates **post-hepatic (obstructive)** jaundice - Pale stools confirm complete bile duct obstruction 2. **Liver Enzyme Profile** - ALP (320 U/L) and GGT (280 U/L) markedly elevated — **cholestatic pattern** - Transaminases only mildly elevated (ALT 45, AST 52) - This disproportionate ALP/ALT ratio is typical of biliary obstruction, NOT hepatocellular injury 3. **Imaging Findings** - Dilated intrahepatic and extrahepatic bile ducts = **upstream obstruction** - Hypoechoic lesion at pancreatic head = **mass effect on common bile duct** - No stones visible on ultrasound 4. **Clinical Presentation** - **Painless jaundice** is a classic red flag for pancreatic malignancy - Absence of fever/RUQ pain rules out acute cholecystitis/cholangitis - Absence of weight loss in this case does NOT exclude cancer (early presentation) ### Differential Diagnosis Table | Feature | Pancreatic CA | Choledocholithiasis | PBC | Autoimmune Hepatitis | | --- | --- | --- | --- | --- | | **Onset** | Insidious, painless | Acute, colicky pain | Insidious, pruritus | Insidious, variable | | **ALP/ALT ratio** | High (cholestatic) | High | Very high | Low (hepatocellular) | | **Imaging** | Pancreatic mass + duct dilation | Stone in CBD | Bile duct proliferation | Normal or cirrhotic liver | | **Age/Risk** | >50 years, smoking | Any age, female, stones | Middle-aged women | Young-middle aged, autoimmune | | **Fever** | No (unless infected) | Yes (if cholangitis) | No | No | **High-Yield:** Pancreatic head cancer classically presents with **painless obstructive jaundice** + dilated CBD on imaging. This is a board-favorite vignette. ### Mechanism of Jaundice ```mermaid flowchart TD A[Pancreatic head adenocarcinoma]:::outcome --> B[Compression of common bile duct] B --> C[Complete biliary obstruction] C --> D[Conjugated bilirubin accumulation] D --> E[Jaundice + pale stools] C --> F[ALP/GGT elevation] F --> G[Cholestatic pattern on LFTs]:::outcome ``` ### Why This Is the Answer - **Painless jaundice** + **pancreatic head mass** on imaging = pancreatic cancer until proven otherwise - Cholestatic LFT pattern (high ALP, normal transaminases) confirms **post-hepatic obstruction** - No fever or acute presentation excludes acute cholangitis - No pruritus, autoantibodies, or cirrhotic features exclude PBC/autoimmune hepatitis [cite:Harrison 21e Ch 297]