Multifocal Spinal Cord Nephroblastoma in a Dog

A 1-year-old male American pit bull terrier was presented with a history of proprioceptive deficits and mild lameness of the right hindlimb, which progressed after 5 months to paraparesis, culminating in tetraparesis after 2 weeks. Necropsy findings were limited to the spinal cord and consisted of multiple, intradural, extramedullary, slightly red masses which produced segmental areas of medullary swelling located in the cervical intumescence, thoracolumbar column, sacral segment and cauda equina. Histological evaluation revealed a tumour, composed of epithelial, stromal and blastemal cells, with structures resembling tubules, acini and embryonic glomeruli. Immunohistochemical labelling for vimentin, cytokeratin and S100 was positive for the stromal, epithelial and blastemal cells, respectively. A final diagnosis of multifocal spinal cord nephroblastoma was established. This is the first report of such a tumour showing concomitant involvement of the cervicothoracic, thoracolumbar, sacral and cauda equina areas of the spinal cord.