Topic Completed: 1 September 2011

Minor changes: 23 July 2020

Copyright: 2003-2020,, Inc.

PubMed search: echinococcal [title] cyst pulmonary

Elliot Weisenberg, M.D.
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Cite this page: Weisenberg E. Echinococcus. website. Accessed October 20th, 2020.
Clinical features
  • Also called hydatid cyst
  • Humans become infected by eating food contaminated with tapeworm eggs, becoming intermediate hosts
  • Eggs from dog tapeworm Echinococcus granulosus or E. multilocularis where foxes are the most common definitive hosts; other species rarely cause hydatid diseae in humans
  • For E. granulosus, sheep are most important intermediate hosts; for E. multilocularis, rodents are most important intermediate hosts
  • E. granulosus is more common in humans and is most common cestode infection of the lung
  • Eggs hatch in duodenum and spread to liver, lung, bone or elsewhere
  • E. granulosus cysts are most common in liver, 5% - 15% occur in lung; pulmonary disease is often secondary to hepatic disease (World J Surg 2001;25:46)
  • Larvae lodge in capillaries and incite a mononuclear and eosinophilic inflammatory cell response
  • Many larvae die, some encyst
  • Pulmonary cysts may be asymptomatic or cause respiratory compromise by compressing airways or lung parenchyma; rarely complicated by Aspergilloma (Br J Radiol 2008;81:e279)
  • Cyst rupture may cause fatal anaphylactic shock or pneumonia with consequent development of numerous new cysts throughout lung
Case reports
Microscopic (histologic) description
  • Cysts gradually enlarge and years later may be several centimeters in diameter
  • Cyst is bilayered and surrounded by fibroblasts, mononuclear cells, eosinophils, multinucleated giant cells
  • Daughter cysts usually develop in large mother cyst
  • Daughter cysts develop as projections from a germinative layer and form brood capsules
  • Degenerating scolices of developing worms produce sediment, so called "hydatid sand"
Microscopic (histologic) images

Contributed by Dr. Hanni Gulwani

Cytology images

Images hosted on other servers:
2 cm lung nodule 2 cm lung nodule 2 cm lung nodule 2 cm lung nodule

2 cm lung nodule

BAL fluid - scolices

BAL fluid - scolices

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