Induction of malignant vascular tumors of the liver in guinea pigs treated with 2,2'-dihydroxy-di-n-propylnitrosamine.

The effect of chronic administration of 2,2'-dihydroxy-di-n-propylnitrosamine (DHPN) was studied in randombred guinea pigs. DHPN, dissolved in olive oil, was injected sc into 40 animals at a dose of 250 mg/kg body weight/week for 30 weeks, and the animals were observed until their death or termination of the experiment at the end of 40 weeks. Of the 32 guinea pigs that survived more than 20 weeks of DHPN treatment, 23 developed angiosarcoma of the liver between 22 and 40 weeks. Metastases to lungs, spleen, and peripancreatic lymph nodes were observed in 8 animals. Other tumors included hepatocellular carcinoma (1 animal), cholangiocarcinoma (1 animal), chronic myeloid leukemia (1 animal), acinar cell adenoma of pancreas (1 animal), and acinar cell carcinoma of pancreas (1 animal). In addition, megalocytic change of hepatic cells with intranuclear inclusions, pelliosis hepatis, and cholangiomatous lesions were also encountered frequently in the livers.