Echinococcus osteomyelitis

Author: Dariusz Borys, M.D. (see Authors page)

Revised: 14 September 2016, last major update June 2012

Copyright: (c) 2003-2016,, Inc.

PubMed Search: Echinococcus osteomyelitis
Cite this page: Echinococcus osteomyelitis. website. Accessed October 22nd, 2016.
Definition / General
  • Rare; due to infection by larva of Echinococcus tapeworms
  • Usually E. granulosus, also E. multilocularis and E. oligarthrus
Life cycle
  • Tapeworm’s gravid segment breaks off from implantation site in small intestine of dogs, coyotes and wolves (in North America), disintegrates in colon releasing eggs which pass in feces
  • Eggs are ingested by sheep, goats, deer, moose, humans
  • Hatch in small intestine, disseminate via blood
  • At implantation site, larva secrete hyaline membrane that differentiates into outer acellular laminated structure and inner germinal layer which produces protoscolices
  • Cysts may be ingested by dogs
  • Cysts may rupture and produce fever, urticaria, anaphylactic shock, dissemination of infection, pathologic fractures if in bone
  • 60% liver
  • 20% lungs
  • 3% brain
  • 1% bones (50% in lower vertebrae)
Radiology Description
  • Extensive complex cystic changes
Case Reports
  • Excision, albendazole or praziquantel
Gross Description
  • Ragged surface
  • Multiple cavities filled with red-brown necrotic material and yellow-white cystlike structures
Micro Description
  • Acellular laminated membranes with germinal layer
  • Rare degenerating scolices and hooklets
  • Intense acute and chronic inflammatory infiltrate may erode bone
Micro Images

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Cytology Description
  • Hydatid sand (free daughter cysts, free scolices)
Positive Stains
  • PAS and GMS (membranes)