Abstract
The association of sarcoma of the liver of rats with Cysticercus fasciolaris, the larval stage of Tenia crassicollis of the cat, has been noted by a number of investigators, including two of the present authors; but to our knowledge no one has hitherto reported the experimental production of tumors by the employment of this parasite as an agent. The purpose of the present note is to record several cases of sarcoma of the liver in a group of 500 rats infested with the Cysticercus by feeding the animals eggs of the Tenia obtained from cat feces. Two hundred and fifty of these rats were alive when the first tumor was discovered, and 170 are still under observation.
Large tumors were discovered in the livers of four rats, 296 to 357 days after feeding. In each case the tumor originated in the wall of a single Cysticercus cyst, one of 30 to 50 present in this organ. Each of the involved cysts contained a worm about 20 cm. long, only one of which was living. Three of the tumors had metastasized freely into the peritoneal tissues. In each of two of the animals early and probably independent malignant changes had occurred in the walls of other cysts in the liver. Histologically, the tumors were sarcomata of either the spindlecell or polymorphous-cell type. The transplantation of two of them into young rats resulted in 92 and 46 per cent. respectively of successful inoculations. The other two were not transplanted.
Complete data on a fifth rat which bore a tumor is lacking due to the loss of the liver through partial evisceration of the animal by his cage maltes. The peritoneal tissues were, however, studded with tumor nodules which histologically proved to be spindle-cell sarcoma.
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