Spontaneous vascular neoplasms in aged Sprague-Dawley rats.

Primary benign and malignant vascular neoplasms occurred spontaneously in 8 of 710 male (1.1%) and 4 of 710 female (0.6%) Crl:CD Br strain Sprague-Dawley rats employed in two 2-yr oncogenicity studies (1,400) and as controls in a 1-yr toxicity study (20). Four of 13 neoplasms were found in the spleen; skin and kidney each had 2 neoplasms. Single vascular neoplasms were in the liver, testicle, uterus, mesenteric lymph node, and vagina. Hemangioma was more common (5 males, 2 females) than hemangiosarcoma (3 males, 2 females). Vascular neoplasms were considered the cause of death in 2 females, both with hemangiosarcomas involving the spleen or kidney. One male had 2 primary hemangiomas in separate organs. Vascular neoplasms are infrequently reported [1/82 females (1.2%), 1961; 9/880 both sexes (1.0%), 1985] in this rat strain. The incidence of vascular neoplasms of this report was higher in males (9) than in females (4), in contrast to incidences reported in the literature.

Hemobartonella-like parasites in cynomolgus monkeys (Macaca fascicularis).

Red blood cell parasites were identified electron microscopically in five anemic adult female cynomolgus monkeys (Macaca fascicularis), two of which died during anemic episodes. Organisms typically were 0.3-0.5-micron round, oval, or reniform bodies on the surface or within vacuoles of erythrocytes. Based on their size, location in the erythrocyte, and internal ultrastructural features, organisms were classified as Hemobartonella-like. The relationship between the organisms and the anemias in these monkeys was unclear. This report adds rickettsial erythrocyte infections to the list of latent infections that can complicate research studies with cynomolgus monkeys.

Spontaneous skin neoplasms in aged Sprague-Dawley rats.

A total of 93 tumors of the epidermis, its appendages, and dermis were observed in 1,433 (717 males, 716 females) rats employed in oncogenicity studies over a 2-yr period. Mammary gland neoplasms will be reported separately. Fifty-seven (61.3%) were epithelial with 49 in males and 8 in females. Keratoacanthoma was the most frequent epithelial neoplasm in males (22) followed by squamous cell carcinoma (11) and papilloma (5). Sebaceous gland neoplasms seen in males (5) included both adenomas (3) and carcinomas (2). In males, there were also 3 trichoepitheliomas, 1 pilomatricoma, 1 basal cell tumor, and 1 malignant melanoma. Of the 8 epithelial neoplasms in females, there were 3 squamous cell carcinomas, 2 keratoacanthomas, and 1 each basal cell tumor, malignant melanoma, and trichoepithelioma. There were 21 mesenchymal neoplasms in males and 15 in females. The most frequent neoplasm was fibroma (7 males, 8 females) followed by lipoma (7 males, 4 females) and fibrosarcoma (4 males, 3 females). One male had a liposarcoma and 2 males each had hemangioma. The total neoplasm incidence of 70/717 (9.8%) in males and 23/716 (3.2%) in females showed that skin neoplasms were 3 time more common in males than in females. Epithelial neoplasms of the skin were 6 times more common in males than in females. Males were more than twice as likely to have epithelial rather than mesenchymal skin neoplasms whereas the reverse was seen in females.

Spontaneous brain and spinal cord/nerve neoplasms in aged Sprague-Dawley rats.

Primary malignant neoplasms of the brain and spinal cord occurred in 20/718 male (2.8%) and in 13/717 female (1.8%) Crl:CD Br strain Sprague-Dawley rats. Of 33 neoplasms, 30 were found in brain while 3 were in the spinal cord. In males and females, the most common brain neoplasm was astrocytoma (13 males, 9 females). Other neoplasms, granular cell tumor (1 male), mixed glioma (2 males, 1 female), reticulosis (1 male, 2 females), and oligodendroglioma (2 males), were especially uncommon. Spinal cord neoplasms included 2 schwannomas (1 male, 1 female) and an astrocytoma (1 male). The overall brain neoplasm incidence was similar for males (2.8%) compared to data compiled for this strain, and there was a 2-fold increase for females (1.8% vs 0.9%) compared to available incidence data.

Naturally occurring intestinal epithelial neoplasms in aged Crl:CD BR rats.

Spontaneous primary epithelial neoplasms of the intestinal tract occurred in 6/682 (0.9%) male and 1/694 (0.1%) female Sprague-Dawley rats. Six of 7 neoplasms were adenocarcinomas, and 1 of 7 was an adenoma. Metastasis to the liver or lung occurred in 3 of the rats with adenocarcinoma. These findings are consistent with those reported for female Sprague-Dawley rats and for males and females of other strains over the past 25 years. The intestinal neoplasm incidence in males exceeded that reported for other Sprague-Dawley males with one exception, reported 30 years ago.

Spontaneous renal neoplasms in aged Crl:CDBR rats.

Primary neoplasms of the kidneys occurred in 11/682 male (1.6%) and 2/694 female (0.3%) Crl:CDBr strain Sprague-Dawley rats. Eight of 13 neoplasms were of mesenchymal origin and 5 of 13 were epithelial. Five neoplasms were lipoma (3) or liposarcoma (2). Three of 13 were either hemangioma (1) or mesenchymal tumors (2). The epithelial neoplasms were carcinomas. There was no microscopic evidence of metastasis among those neoplasms judged malignant on morphologic criteria. The overall natural incidence in males was nearly double that compiled for this strain while in females the incidence was similar to that reported for other females.