Osteosarcoma Case Study

DL is a 17 year old young adult who presented with 3 months of worsening left knee pain. This began insidiously without any injury and progressed in intensity over time. By the time he saw his doctor, it had gotten to the point where he was unable to bear any weight on the leg due to severe pain, and had started using crutches. He does not have any other medical conditions and is otherwise very healthy. He is active in sports, and likes to play basketball.

Xray

Imaging was done, starting with Xrays, which showed a large, cloud-like calcified area around the left distal femur. This imaging demonstrates some typical features of an osteosarcoma: a bony matrix being produced by the tumor, periosteal elevation with areas of “onion-skinning”, which represents layer upon layer of ossifying periosteum, and areas of “hair on end”, which represents radially outward growth of the tumor being visualized as linear ossification. The native cortex of the bone is poorly visualized in areas of the tumor, suggesting that it has been dissolved by the tumor, a clear indication of the malignant nature of the mass.

MRI

Further cross-sectional imaging with MRI demonstrates the relationship to the joint, and the nerves and blood vessel of the popliteal fossa.

A biopsy is performed demonstrating a classic osteosarcoma. Bone scan of the entire skeleton, and a CT scan of the chest complete the staging process to understand the full extent of the tumor. Laboratory values such as alkaline phosphatase provide prognostic value prior to initiating treatment. The first step in management is a neo-adjuvant chemotherapy regimen. During this time, the patient is kept on crutches and care is taken not to fracture the delicate tumor.

Endoprosthesis

Once the initial chemotherapy is completed, the tumor is removed and the leg is reconstructed in a single surgical procedure. In this case, this is accomplished with a limb-sparing surgical excision, maintaining the native vessels and nerves. The resection resulted in negative margins, which is the intended result. Once the tumor is removed, a metallic internal femoral implant, called and “endoprosthesis” is used to rebuild the defect. This is mated to a hinged total knee replacement to provide knee function. This will take approximately two months to incorporate into the host bone, at which point the patient can put his full weight on the leg.

Once the operation is completed, the resected specimen is studied for various prognostic factors, including  and most importantly the Huvos Grade, which is a pathological assessment of the percent of necrosis in an osteosarcoma resected specimen. The desired finding is to have a Huvos Grade of greater than 95% necrosis of the tumor from the initiation chemotherapy. This portends the best prognosis for the patient. In this case, the Huvos Grade was greater than 99% necrosis, which was welcome news for DL and his family.

The remainder of the chemotherapy regimen is carried out after surgery, which a short break incorporated for healing time. The total treatment time is lengthy, and we usually tell patients to expect about a year of treatment overall. This can vary somewhat, but it is important that the patient have a good understanding that it is a long process, but one that can be highly effective. DL is now getting close to the end of this regimen, is walking well, and is looking forward to resuming his life as a teenager.