Hydatid disease of the brain

  • Two main types – cystic and alveolar. Cystic more common
  • Definitive host – dog
  • Intermediate host – sheep and cattle
  • Accidental host – man
  • Infected via feco-oral transmission
  • CNS involvement in 4% of cases
  • Hematogenous spread of embryos from gastrointestinal tract 
  • Large, isolated, unilocular, well-defined and thin-walled cysts
  • Small daughter cysts arranged peripherally within large maternal cyst – pathognomonic of hydatid cyst
  • Cyst fluid follows CSF signal/density
  • Active cysts: thin rim of enhancement and mild perilesional edema
  • Late stage: calcification may be seen, dead cyst
  • Alveolar form: high mortality rate, numerous irregular small cysts. Heterogeneous, nodular or cauliflower like enhancement
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El-Shamam, Omran, Talal Amer, and Mohamed Abo El-Atta. “Magnetic resonance imaging of simple and infected hydatid cysts of the brain.” Magnetic resonance imaging 19.7 (2001): 965-974.

Pedrosa, Iván, et al. “Hydatid Disease: Radiologic and Pathologic Features and Complications 1: (CME available in print version and on RSNA Link).” Radiographics 20.3 (2000): 795-817.