Hydatid cyst (echinococcosis)
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It has 3 layers in cyst wall:
A) Germinal layer (innermost)
● it contains nuclei, gives rise to brood capsules attached by short stalk in infectious (fertile) cysts
● Often with daughter cysts
● Also protoscolices (attached or separated) with double row of refractile, birefringent, acid-fast hooklets 22-40 microns and 4 round suckers that comprise “hydatid sand”
● Daughter cysts may merge and provide internal septation
B ) laminated membrane
● beneath germinal layer.
● avascular, eosinophilic, refractile and chitinous.
C)Dense fibrovascular tissue (outer layer)
●It may have chronic inflammatory cells.
●Variable calcification develops after 5+ years.
