What's the most likely diagnosis?

• 51 year-old male with mild RUQ pain

Contrast-enhanced axial CT of upper abdomen

1. Auto-infarction of spleen
2. Hydatid liver cyst
3. Cirrhosis
4. Rupture of the diaphragm
5. Carcinoma of the stomach

Additional Image - Coronal CT reconstruction

 

Additional Image

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Coronal CT reformatted image of abdomen

Answer:

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3. Hydatid Liver Cyst

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Hydatid Cyst of Liver

General Considerations

• Parasitic infestation caused by Echinococcus tapeworm
• Endemic to Middle East, Africa, Iceland, Australia, southern parts of South America
  • Very rare in US
• Cysts grow slowly and usually don’t become symptomatic until adulthood (30-50 years old)
• Three species which cause human disease are
  • E. granulosus (aka granulosa, granulosis) causes Cystic Echinococcosis (CE) (most common)
  • E. multilocularis causes Alveolar Echinococcosis (AE) –most virulent
  • E. vogeli—rarest
• Infestation of humans, who are accidental intermediate hosts, occurs from ingestion of water or food contaminated by fecal material of definitive hosts (dogs, wolves, deer, sheep, coyotes)
  • Eggs hatch in duodenum and pass as larvae through intestinal wall into blood stream to liver and lungs

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