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Difficulty: HardMedical History Evaluation

A 48-year-old man presents to the emergency department with a 33-day history of high fever and severe right upper quadrant abdominal pain. He was initially evaluated at an urgent care clinic yesterday, where he was told he likely had a "gallbladder infection" and was referred to the hospital. His past medical history is notable for type 2 diabetes mellitus and hypertension. He emigrated from rural Peru 66 months ago. Temperature is 39.2∘C39.2^\circ\text{C} (102.6∘F102.6^\circ\text{F}), blood pressure is 110/70110/70 mmHg, and heart rate is 108108/min. Physical examination reveals significant tenderness to palpation in the right upper quadrant, with marked hepatomegaly. No scleral icterus is noted. Laboratory studies show a leukocyte count of 18,00018,000/mm 3^3, total bilirubin of 1.41.4 mg/dL, and alkaline phosphatase of 350350 U/L. Right upper quadrant ultrasound demonstrates a single, 88 cm hypoechoic mass in the right hepatic lobe with well-defined margins; there are no visible gallstones or biliary ductal dilation. Upon further historical questioning, the patient reports having a chronic, nonproductive cough that recently changed; he is now coughing up dark, reddish-brown material that he describes as resembling "anchovy paste." Based on a comprehensive evaluation of the patient's history and diagnostic findings, which of the following is the most likely etiology of his presentation?

  1. A
    Ascending bacterial infection of the biliary tree due to an obstructing calculus
  2. B
    Ingestion of tapeworm eggs leading to cystic hepatic disease
  3. Invasive intestinal protozoan infection with extraintestinal spreadAnswer
  4. D
    Biliary tract infestation by trematodes acquired from raw freshwater fish
  5. E
    Reactivation of a latent mycobacterial infection with hepatic dissemination

Answer

Invasive intestinal protozoan infection with extraintestinal spread
The correct answer is an invasive intestinal protozoan infection with extraintestinal spread, specifically caused by Entamoeba histolytica. The clinical presentation of a solitary right upper lobe liver mass in a patient from an endemic region strongly suggests an amebic liver abscess. The critical historical finding of coughing up 'anchovy paste' sputum is pathognomonic for the rupture of the abscess through the diaphragm into the pleural space and bronchial tree, creating a hepatobronchial fistula. Eliciting and recognizing this specific historical detail allows the clinician to avoid the cognitive trap of premature closure regarding a standard biliary infection.

Step-by-Step Solution

1
Analyze the initial presentation and ultrasound findings.
The patient has fever, right upper quadrant pain, and a large solitary hypoechoic liver mass without biliary dilation or gallstones.
To establish the primary pathology (a liver abscess) and rule out the anchoring diagnosis of a primary gallbladder infection (cholecystitis/cholangitis).
2
Evaluate the critical historical elements.
The patient recently emigrated from an endemic region (Peru) and developed a cough producing 'anchovy paste' sputum.
To differentiate the etiology of the liver mass. Travel history suggests parasitic or endemic infections, and the specific sputum character is a pathognomonic diagnostic clue.
3
Synthesize the history and objective findings.
The combination of a liver abscess and 'anchovy paste' sputum points definitively to an amebic liver abscess that has ruptured through the diaphragm.
Entamoeba histolytica causes extraintestinal amebiasis, classically presenting as a right-lobe liver abscess that can form a hepatobronchial fistula, yielding this characteristic sputum.

Key Concept

Evaluating historical clues to avoid premature closure and identify complications of amebic liver abscess (hepatobronchial fistula).
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Topics

Medical History Evaluation

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