Multilobular osteochondrosarcoma in 39 dogs: 1979-1993.

Thirty-nine, older, large-breed dogs with multilobular osteochondrosarcoma (MLO) each presented primarily with a fixed mass involving the flat bones of the skull. Twenty-five dogs were treated with surgical resection alone, nine were treated with adjuvant therapy, and five were not treated. Forty-seven percent of dogs treated had local tumor recurrence, and 56% had metastasis. Median time to recurrence, median time to metastasis, and median survival time were 797, 542, and 797 days, respectively. Histological grade, surgical margins, and tumor location affected outcome. Long-term remission can be obtained with aggressive treatment of MLO, although it is locally invasive and moderately metastatic.