Clinical case study: Surgical treatment of multilobular osteochondrosarcoma

multilobular osteochondrosarcoma
Sagittal, axial and coronal CT views of Ace’s pelvis at the same level. Note the large, multi-lobular, mineralised, well circumscribed mass emanating from the pelvis on the right, medial side of the acetabulum causing obliteration of the pelvic canal with very little lysis of the pelvic bones.

Ace is a 10-year-old male, neutered, crossbred dog weighing about 30kg. He presented in February of 2017. He was unable to defecate and had severe stranguria due to a large firm mass almost obliterating his pelvic canal. A diagnosis of osteosarcoma (OSA) of the pelvis had been made about four months previously and a soft tissue sarcoma (STS) had been incompletely removed from his proximal right thigh. Given that the histological diagnosis of axial OSA carries a poor prognosis and wide resection was problematic, the owner elected to have palliative care and presented as a last resort to see if Ace could at least be made to defecate.

He had a very hard but smooth and well demarcated mass in his pelvis fixed to his right medial ilium and ischium at about the level of his acetabulum. His STS had not recurred and he had no evidence of metastatic disease. Because of the smooth and well demarcated nature of his intrapelvic lesion and the fact that the progression had been slow without metastasis, a low grade bone tumour such as parosteal osteosarcoma was considered likely and Ace’s owner agreed to a CT to determine if resection would be possible.

On CT, a large, multi-lobular, mineralised, well circumscribed mass was seen emanating from the pelvis on the right, medial side of the acetabulum causing obliteration of the pelvic canal but there was very little lysis of the pelvic bones. Ace was taken immediately to surgery under the same anaesthetic and a right hemipelvectomy was performed. The tumour was not an osteosarcoma but histopathology confirmed a completely excised, low-grade, multilobular osteochondrosarcoma. This is a curable disease and Ace has a very good prognosis. Ace was able to walk on his remaining three legs the next day and enjoyed many very effective, continent bowel motions as well as urinating freely. Although his unrelated STS of the proximal thigh did recur and require resection and radiation some time later, he remains disease free nearly a year on. He loves being with his dad and he has a great life.

This is the specimen seen from the medial or intrapelvic side. This is the immediate post-operative appearance after the right hemipelvectomy. It is virtually identical to a standard coxofemoral hind limb amputation. Note the closed suction Jackson-Pratt drain.

This case demonstrates what can be done in a seemingly hopeless situation. Hemipelvectomy is a huge surgery but one from which animals recover well and quickly. In the right circumstances, like with a curable cancer such as Ace’s, the procedure is lifesaving. The team of experienced surgeons, residents, house officers, nurses and support staff at BVSC have the equipment, facilities and expertise to produce some wonderful and amazing results for cancer patients like Ace. 


Founding Fellow Surgical Oncology – Small Animal Surgery (Oncology), Specialist Head of Oncology & Director of BVSC

Dr Rod Straw is originally from Melbourne where he graduated from The University of Melbourne. He trained in the United States at the University of Missouri at Columbia and Colorado State University becoming the world’s first Fellow in Veterinary Surgical Oncology. He was on faculty at Colorado State University until establishing Australia’s first veterinary oncology program in 1995. Dr Straw has dedicated his veterinary career to cancer treatment and research, only treating animals with cancer since 1986.

Having founded Brisbane Veterinary Specialist Centre in 2004, The Australian Animal Cancer Foundation in 2006 and the Australian Consortium of Clinical Oncology in 2015, Dr Straw is dedicated to improving animal health through specialist care with compassion while finding a cancer cure for pets and people. 

Read more about Dr Rod Straw at


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