**Question:** A 45 years male presented with chief complaints of abdominal pain with associated nausea, diarrhea, fatigue, abdominal discomfort, anorexia, weight loss, diarrhea, and jaundice. On imaging of the liver with ultrasound, it shows intra- and extra-hepatic dilatation and strictures with intraductal pigmented stones, What can be the causative agent?

A. Viral hepatitis
B. Primary sclerosing cholangitis
C. Primary biliary cholangitis
D. Pancreatic cancer

**Core Concept:**

The clinical presentation and imaging findings described in the question suggest a condition affecting the biliary system, which is responsible for the production and excretion of bile from the liver to the intestine. The presence of intra- and extra-hepatic dilatation and strictures with intraductal pigmented stones indicates a cholestatic liver disease. Cholestasis is the blockage of the bile ducts, leading to the accumulation of bile pigments (bilirubin) in the liver cells, causing jaundice.

**Why the Correct Answer is Right:**

The correct answer is **B. Primary sclerosing cholangitis**. Primary sclerosing cholangitis (PSC) is a chronic inflammatory condition affecting the bile ducts, leading to cholestasis and subsequent manifestations like jaundice, abdominal pain, and weight loss. The strictures, dilatation, and pigmented stones are characteristic features of PSC on imaging studies like ultrasound and MRCP (Magnetic Resonance Cholangiopancreatography).

**Why Other Options are Incorrect:**

A. Viral hepatitis (A) is an acute or chronic infection caused by hepatitis viruses. Though it may present with jaundice and abdominal pain, the characteristic features of cholestasis are not as evident as in PSC.

C. Primary biliary cholangitis (C) is another cholestatic liver disease, but it primarily affects the bile ducts in the liver (not extrahepatic as in PSC). The other features like abdominal pain and weight loss are also less prominent compared to PSC.

D. Pancreatic cancer (D) is a primary malignancy of the pancreas, not the bile ducts. Although it can present with jaundice, abdominal pain, and weight loss, the imaging findings of strictures, dilatation, and pigmented stones are distinct to PSC.

**Clinical Pearls:**

Primary sclerosing cholangitis is a rare condition that requires a high index of suspicion, as the presentation may be non-specific and overlap with other liver diseases. It is essential to consider PSC when evaluating patients with cholestatic liver disease, especially in the absence of alternative causes such as viral hepatitis or malignancies.

**Characteristic Features of PSC:**

The key features of PSC include cholestasis with extrahepatic duct involvement, strictures, dilatation, and pigmented stones in the bile ducts. These features are not typically seen in viral hepatitis or pancreatic cancer, making PSC a more likely diagnosis in this scenario. The presence of ja