Pathology of the intervertebral disks and other spinal lesions in 31 aging inbred mouse strains

In a large-scale aging study of 31 inbred strains of mice, a variety of age-related lesions arose in and around the spine (vertebrae, spinal cord, and adjacent connective and muscle tissues), including lesions of intervertebral disks, vertebrae, muscles, soft tissues, nerves, ganglia, and spinal cord that were either sporadic or strain-specific. In most cases, the mice did not present with obvious clinical signs, as many lesions were mild. Lesions included herniated or displaced intervertebral disk fragments, which appeared to be sporadic in most strains but were common in others. Fibro-osseous lesions of bones were a systemic disease in female mice with no effect on disk disease. Rhabdomyosarcomas were common in A/J mice surrounding the vertebrae but also invaded into the spinal canal, sometimes almost transecting the cord. Lymphomas affected all AKR/J mice, sometimes infiltrating into the spinal canal. Muscular dystrophy of the musculature surrounding the spine, due to mutations in the dysferlin (Dysf) gene, was common in A/J and SJL/J mice. Coccygeal hemivertebra was a novel strain-specific lesion only in PL/J mice. Sporadic lesions in and around the spine included hemangiosarcomas, lymphomas (both enlarged lymph nodes and invading in and around the vertebrae), schwannomas, histiocytic sarcomas, poorly differentiated sarcomas, and epidermoid/dermoid cysts. Since these strains have all been sequenced and annotated, polymorphisms in genes known to affect the pathogenesis of some of these lesions will be reported in other publications.