Age/sex: unknown
Size: 29.2 x 14.5 x 6.6 cm
The bottom two-thirds of this liver slice are normal. The upper part has been replaced by a well-circumscribed tumor-like mass composed of innumerable cysts 1 鈥� 2 mm in diameter.
Echinococcus
Echinococcus听is a tapeworm that causes disease primarily in wild and domestic animals. The adult worm lives in the intestine of the definitive host (a carnivore, such as a dog, fox, or coyote) in whom it lays numerous eggs that are passed in the stool. These are ingested by an intermediate host (usually a rodent, such as a vole) in whom they hatch and develop into small cysts that form larvae. The life cycle of the worm is completed when the definitive host eats an infected intermediary host following which the ingested larvae attach to the intestinal mucosa and develop into adult worms. Humans are usually affected 鈥渁ccidentally鈥� by handling infected animals or ingesting contaminated water or vegetable material.
Disease caused by E. multilocularis, as in this specimen, is called alveolar hydatid disease and is characterised by the presence of numerous millimeter size cysts. It is much less common than cystic hydatid disease, which is caused by E. granulosus. 听The latter has a similar life cycle to E. multilocularis, but with sheep, goats, cattle, etc as intermediary hosts. Its cystic form typically consists of only one or two cysts that measure several centimeters in size.
Below: Adult E. multilocularis tapeworm.
Source: Walker, AR. (2012). Echinococcus multilocularis adult. Wikimedia Commons.
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