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Open Access Squamous Cell Carcinomas of the Skin at Ear Tag Sites in Aged FVB/N Mice

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We report the development of squamous cell carcinomas (SCCs) of the skin at or near the site of ear tags composed of a nickel–copper alloy and used for identification during the course of a long-term study of incipient congenic FVB/N mice containing the human BCL6 transgene (FVB.Cg-Tg[tetO-BCL6]Bbn Tg[ESR-tTa]83Bop), their littermate controls, and wild-type FVB/N. Of a total population of 160 mice, 14 (8.8%) developed SCCs in the tagged (right) ear after a median observation period of 25 months, but none of the animals developed tumors in the opposite ear (P = 0.0001). Nine of the fourteen mice with SCCs had to be euthanized because they were thought to be in distress from the ear condition, but the remaining five died or were euthanized for other reasons related to the research study. These animals ranged in age from 331 to 921 days at the time of death. Five of the tumors were well-differentiated (grade 1) SCCs; the remainder were grade 3 and tended to be deeply invasive neoplasms with undifferentiated areas containing a spindle cell component. One of these metastasized to kidney. When using the FVB/N mouse strain for long-term studies, it is necessary to consider that nearly 9% of the population may develop SCCs at or near ear-tag sites that may necessitate early removal of the animal.

Document Type: Research Article

Affiliations: 1: Department of Pathology, The University of Chicago, Chicago, Illinois 60637 2: Department of Surgery, The University of Chicago, Chicago, Illinois 60637 3: Department of Health Studies, The University of Chicago, Chicago, Illinois 60637 4: Department of Medicine, The University of Chicago, Chicago, Illinois 60637

Publication date: 2005-06-01

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  • Comparative Medicine (CM), an international journal of comparative and experimental medicine, is the leading English-language publication in the field and is ranked by the Science Citation Index in the upper third of all scientific journals. The mission of CM is to disseminate high-quality, peer-reviewed information that expands biomedical knowledge and promotes human and animal health through the study of laboratory animal disease, animal models of disease, and basic biologic mechanisms related to disease in people and animals.

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