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Difficulty: HardPathology and Biopsy Interpretation

A 48-year-old woman undergoes a percutaneous liver biopsy to evaluate persistently abnormal liver biochemistries. Over the past year, she has experienced worsening fatigue and generalized pruritus. Her medical history is notable only for hypothyroidism managed with levothyroxine. Laboratory evaluation shows an alkaline phosphatase of 410 U/L, aspartate aminotransferase of 55 U/L, and alanine aminotransferase of 62 U/L. Total bilirubin is 1.0 mg/dL. An abdominal ultrasound demonstrates a homogeneous liver echotexture with no intrahepatic or extrahepatic biliary dilatation. The liver biopsy specimen reveals expanded portal tracts with a dense lymphoplasmacytic infiltrate and scattered eosinophils. The inflammatory cells are centered around small interlobular bile ducts, demonstrating epithelial cell swelling, vacuolization, and disruption of the ductal basement membrane. Several poorly formed, noncaseating granulomas are intimately associated with these damaged ducts. The surrounding hepatic lobules are largely preserved. Based on these histopathologic findings, which of the following is the most definitive diagnosis?

  1. A
    Primary sclerosing cholangitis
  2. B
    Autoimmune hepatitis
  3. C
    Hepatic sarcoidosis
  4. Primary biliary cholangitisAnswer
  5. E
    Drug-induced liver injury

Answer

The most definitive diagnosis is Primary biliary cholangitis.
The biopsy describes the classic 'florid duct lesion,' which is the pathognomonic histopathologic hallmark of primary biliary cholangitis. This lesion is characterized by a focal, heavy lymphoplasmacytic and frequently granulomatous inflammatory infiltrate that specifically targets and destroys the small interlobular bile ducts. This tissue diagnosis perfectly aligns with the patient's demographic profile (middle-aged woman), cholestatic liver enzyme pattern (disproportionately elevated alkaline phosphatase), and symptoms of fatigue and pruritus.

Step-by-Step Solution

1
Analyze the patient's clinical presentation and laboratory profile.
A middle-aged woman presents with fatigue, pruritus, and a prominent cholestatic pattern of liver injury (disproportionately elevated alkaline phosphatase with normal imaging).
This specific clinical pattern localizes the pathology to an intrahepatic cholestatic process, narrowing the differential diagnosis significantly.
2
Interpret the specific histopathologic findings from the liver biopsy.
The biopsy shows a portal lymphoplasmacytic infiltrate with poorly formed noncaseating granulomas that are selectively targeting and destroying small interlobular bile ducts.
Identifying the specific anatomical target of the inflammation (the interlobular ducts) and the nature of the damage (granulomatous destruction) is the critical step in establishing the diagnosis.
3
Synthesize the clinical and histologic data to reach a definitive diagnosis.
The finding of granulomatous destruction of small interlobular bile ducts is known as the 'florid duct lesion,' which confirms the diagnosis of primary biliary cholangitis.
This classic histopathologic lesion rules out other causes of portal inflammation and granulomas that lack this highly specific, targeted biliary destruction.

Key Concept

The histopathologic hallmark of primary biliary cholangitis is the 'florid duct lesion,' characterized by a dense lymphoplasmacytic infiltrate and noncaseating granulomas that specifically target and destroy small interlobular bile ducts.
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Topics

Pathology and Biopsy Interpretation

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