A 45-year-old man from rural Sudan presents with massive splenomegaly, thrombocytopenia (platelets 60,000/μL), and a history of two episodes of hematemesis from esophageal varices in the past 18 months. Liver synthetic function is preserved (albumin 3.8 g/dL, INR 1.1, total bilirubin 0.9 mg/dL). Stool microscopy reveals lateral-spined eggs. Abdominal ultrasound shows echogenic periportal thickening with a "turtle-back" pattern and patent portal vein. The pathologic process marked **B** in the diagram is responsible for his portal hypertension. Which of the following BEST characterizes the mechanism by which this lesion causes portal hypertension?

Question

Accepted Answer

A. Presinusoidal mechanical obstruction of portal venous flow by fibrous thickening of portal tracts, with preservation of hepatic lobular architecture and synthetic function. ## Why option 1 is correct

The structure marked **B** — schistosomal periportal "Symmers pipestem" fibrosis — causes portal hypertension through **presinusoidal mechanical obstruction**. Schistosoma eggs lodge in presinusoidal portal venules and trigger a chronic TH2-mediated granulomatous response that resolves into dense, hyalinized fibrous thickening confined to the portal tracts. Critically, this fibrosis does NOT disrupt the hepatic lobular architecture or impair synthetic function — the patient's preserved albumin, INR, and bilirubin confirm this. This is the defining feature that distinguishes schistosomal hepatic fibrosis from cirrhosis. The mechanical obstruction of portal blood flow at the presinusoidal level produces portal hypertension with splenomegaly, hypersplenism, and varices, while maintaining near-normal liver function until late disease (WHO Schistosomiasis Guidelines 2022; Robbins Pathologic Basis of Disease 11e).

## Why each distractor is wrong

- **Option 2**: Describes cirrhosis with diffuse regenerative nodularity and architectural distortion. Schistosomal fibrosis explicitly preserves lobular architecture and does not cause cirrhosis; this is the cardinal distinction. The patient's normal synthetic function rules out cirrhosis.
- **Option 3**: Characteristic of primary biliary cholangitis (marked **C** in the diagram), which features bile duct loss, cholestasis, and secondary biliary cirrhosis. This patient has no cholestatic markers and stool eggs diagnostic of schistosomiasis.
- **Option 4**: Describes postsinusoidal obstruction (Budd-Chiari syndrome or hepatic vein thrombosis). Schistosomal fibrosis is presinusoidal; the portal vein is patent on ultrasound, and the clinical picture is consistent with presinusoidal hypertension.

**High-Yield:** Schistosomal hepatic fibrosis = **non-cirrhotic portal hypertension** with preserved synthetic function and presinusoidal obstruction; cirrhosis = diffuse architectural distortion with hepatocellular dysfunction.

[cite: WHO Schistosomiasis Guidelines 2022; Robbins Pathologic Basis of Disease 11e]

Answer

B. Sinusoidal endothelial injury and hepatic vein thrombosis causing postsinusoidal obstruction

Answer

C. Diffuse hepatocellular necrosis and regenerative nodularity leading to global architectural distortion and cirrhosis

Answer

D. Intrahepatic cholestasis with bile duct proliferation and loss, resulting in secondary biliary cirrhosis

Explanation

Why option 1 is correct

Why each distractor is wrong

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