Cysts Of The Liver are unusual. Are usually formed by the dilation of a bile-duct, but may be due to an obstruction of the lymphatics.

Echinococcus cysts are comparatively common. Are caused by the Taenia echinococcus, a parasite of the dog. The cysts may be either unilocular or multilocular; in the latter case they may occupy the greater part of the organ. The wall of the cyst consists of an outer connective-tissue layer and an inner cellular layer from which secondary cysts may grow.

These cysts by their pressure cause atrophy of the liver substance, icterus, and ascites. They may rupture into the abdomen, neighboring organs, or at times into the vena cava with general distribution. If bacteria gain entrance, the cysts may become transformed into an abscess. Occasionally the contents of the cysts may be absorbed and replaced by cicatricial tissue.

Parasites

The most common and important is the larva of the Taenia echinococcus, which gives rise to the cysts above described. Entamoeba histolytica in cases of tropical dysentery gains entrance and frequently gives rise to abscess formation, usually single. Coccidium oviforme, a common protozoon in lower animals, has been found in man. It forms growths that resemble somewhat adenomata. The Fasciola hepaticum, Dicrocoelium lanceolatum, in the bile-ducts, and the Schistosoma m haematobium, in the portal vein, are sometimes seen.