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Bone

Osteomyelitis

Echinococcus osteomyelitis


Reviewers: Dariusz Borys, M.D. (see Reviewers page)
Revised: 7 June 2012, last major update June 2012
Copyright: (c) 2003-2012, PathologyOutlines.com, Inc.

General
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● Rare; due to infection by larva of Echinococcus tapeworms
● Usually E. granulosus, also E. multilocularis and E. oligarthrus

Life cycle
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● 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

Sites
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● 60% liver
● 20% lungs
● 3% brain
● 1% bones (50% in lower vertebrae)

Radiology description
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● Extensive complex cystic changes

Case reports
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● 86 year old woman with draining sinus in tibia (Arch Pathol Lab Med 2002;126:1551)
● Disabling pelvic osteomyelitis caused by Echinococcus granulosus (Enferm Infecc Microbiol Clin 1997;15:391)

Treatment
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● Excision, albendazole or praziquantel

Gross description
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● Ragged surface
● Multiple cavities filled with red-brown necrotic material and yellow-white cystlike structures

Micro description
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● 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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H&E, PAS, GMS

Cytology description
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● Hydatid sand (free daughter cysts, free scolices)

Positive stains
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● PAS and GMS (membranes)

End of Bone > Osteomyelitis > Echinococcus osteomyelitis


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