Sarcoma in Animals and Humans

Sarah Boston, DVM, DVSc, DACVS, ACVS Founding Fellow of Surgical Oncology, University of Florida

Andre R. Spiguel, MD, University of Florida

February 2018|Oncology|Peer Reviewed

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Sarcoma in Animals and Humans

This column co-presents clinical cases in a side-by-side format, with the patient—human or veterinary—as the primary variable. It is the hope of the Clinicians Brief team that readers will see the inherent commonalities in managing cases of similar diseases, regardless of species.

The Zoobiquity series is based on Zoobiquity by Barbara Natterson-Horowitz and Kathryn Bowers.


Pelvic Chondrosarcoma & Hemipelvectomy in a Man

HISTORY

A 36-year-old otherwise healthy man with a history of multiple hereditary exostoses (MHE) noticed a painful mass over the right ilium that had slowly enlarged over the past year. He was referred to a musculoskeletal oncologist and presented with previously obtained radiographs.

CLINICAL SIGNS

On physical examination, the patient was pleasant and in no acute distress. He had a large nonmobile mass over the right hemipelvis. He was able to ambulate normally without any deficits. The rest of the examination was otherwise unremarkable.

Anteroposterior radiograph showing a large mineralized mass with poorly defined margins and a wide zone of transition arising from the right ilium
Anteroposterior radiograph showing a large mineralized mass with poorly defined margins and a wide zone of transition arising from the right ilium

FIGURE 1 Anteroposterior radiograph showing a large mineralized mass with poorly defined margins and a wide zone of transition arising from the right ilium

FIGURE 1 Anteroposterior radiograph showing a large mineralized mass with poorly defined margins and a wide zone of transition arising from the right ilium

DIAGNOSIS

Previously obtained anteroposterior pelvic radiographs (Figure 1) showed a large, poorly defined, mineralized lesion involving the right ilium. Because of the patients physical examination results, history of MHE, and radiographic findings, a secondary chondrosarcoma of the right ilium was suspected. Further diagnostic evaluation, including a CT scan (Figure 2) and MRI of the pelvis, were obtained to further characterize the lesion and begin surgical planning.

Axial CT images showing a large mass arising from the right ilium with a significant soft-tissue component in both the inner and outer tables of the pelvis
Axial CT images showing a large mass arising from the right ilium with a significant soft-tissue component in both the inner and outer tables of the pelvis

FIGURE 2 Axial CT images showing a large mass arising from the right ilium with a significant soft-tissue component in both the inner and outer tables of the pelvis

FIGURE 2 Axial CT images showing a large mass arising from the right ilium with a significant soft-tissue component in both the inner and outer tables of the pelvis

Because the lungs are the most common site of metastasis in cases of chondrosarcoma, staging was determined via bone scan and chest CT, which confirmed that there were no other sites of disease. Staging was determined to be Enneking Stage IB; prognosis was good overall. Core needle biopsy confirmed low-grade chondrosarcoma.

Treatment

Low-grade secondary chondrosarcoma with no other sites of disease is treated definitively with resection when possible. Neoadjuvant treatments (eg, radiation, chemotherapy) are of limited value and used only in palliation with limited success.1-3 Because of the patients age and good prognosis, and no need for adjuvant treatment if a negative margin could be achieved, reconstruction was elected to restore the pelvic ring in the setting of an iatrogenic disruption. The right ilium was resected by cutting through the sciatic notch toward the anterior inferior iliac spine and cutting through the sacral ala posteriorly to ensure a negative margin (ie, internal hemipelvectomy), which allowed for preservation of the right acetabulum and right hindquarter (Figures 3 and 4). Reconstruction was performed using lumbopelvic fixation and a double-barrel vascularized free fibula autograft harvested from the ipsilateral leg (Figure 5). Postoperative radiographs showed resection and reconstruction (Figure 6).

OUTCOME

The patient recovered well from surgery. Pain was controlled using a standard lumbar epidural immediately postoperatively. Two days postoperatively, the patient was doing well and the epidural was weaned. Through reconstruction and stabilization of the pelvic ring, the patients recovery was significantly advanced. He was discharged 5 days after surgery on oxycodone (10 mg PO q4-6h as needed for pain) and low-molecular weight heparin for thromboprophylaxis. To protect his construct, he was made toe-touch weight bearing for 3 months.

The patient was seen for surveillance, including radiographs of the pelvis and a CT scan of the chest, every 3 months for 2 years. At 3 years postoperation, surveillance is performed every 4 months, then every 6 months for years 4 and 5 postoperation. After 5 years postoperation, he is considered cured. Because of his history of MHE and increased risk for subsequent secondary chondrosarcomas arising from prior osteochondromas, he will continue to be seen every year for clinical examination, pelvic radiographs, and any imaging of painful or enlarging osteochondromas.

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