Spontaneous neoplasms in mice from a center of a laboratory animal breeding

The prevalence and the pathologic features of spontaneous neoplasms found in mice from a breeding colony were verified. Nine thousand two hundred and nineteen mice belonging to 13 strains were submitted to necropsy from August 2002 to January 2007 for health monitoring. Tissue samples were collected, fixed in 10% buffered formalin, and processed by the usual techniques for inclusion in paraffin. Eighty-four neoplasms were diagnosed and 82 mice had tumors (0.9%). The main neoplasms were diagnosed with the following occurrences: mammary carcinoma, 27.4%; lymphoma, 19.0%; primary papillary pulmonary adenocarcinoma, 17.9%; squamous carcinoma, 8.3%; osteoblastic osteosarcoma, 4.8%; and others with a lower percentage of occurrence. The malignant tumors predominated and the most common tumor was the mammary carcinoma. The wider variety of neoplasm types was found in the BALB/c An strain, followed by the outbred strains Swiss Webster and NIH. The fibrossarcoma in C57BL/10 ScSn-Dmd(mdx)/J mice and mammary carcinoma in NOD mice were reported for the first time.