Clinical Presentation

Subtypes of osteosarcoma

Several subtypes of osteosarcoma can be identified by how they look on x-rays and under the microscope. Some of these subtypes have a better prognosis (outlook) than others.

Based on how they look under the microscope, osteosarcomas can be classified as high grade, intermediate grade, or low grade.

High-grade osteosarcomas: These are the fastest growing types of osteosarcoma. When seen under a microscope, they do not look like normal bone and have many cells in the process of dividing into new cells. Most osteosarcomas that occur in children and teens are high grade. There are several types of high-grade osteosarcomas:

· Osteoblastic

· Chondroblastic

· Fibroblastic

· Mixed

· Small cell

· Telangiectatic

· High-grade surface (juxtacortical high grade)

Other high-grade osteosarcomas include:

· Pagetoid: a tumor that develops in someone with Paget disease of the bone

· Extra-skeletal: a tumor that starts in a part of the body other than a bone

· Post-radiation: a tumor that starts in a bone that had once received radiation therapy

Intermediate-grade osteosarcomas: These uncommon tumors fall in between high-grade and low-grade osteosarcomas. (They are treated as if they are low-grade osteosarcomas.)

· Periosteal (juxtacortical intermediate grade)

Low-grade osteosarcomas: These are the slowest growing osteosarcomas. The tumors look more like normal bone and have few dividing cells when seen under a microscope.

· Parosteal (juxtacortical low grade)

· Intramedullary or intraosseous well differentiated (low-grade central)

The grade of the tumor plays a role in determining its stage and the type of treatment used.

Many patients first complain of pain that may be worse at night, and may have been occurring for some time. If the tumor is large, it can appear as a swelling. The affected bone is not as strong as normal bones and may fracture with minor trauma (a pathological fracture).

However, each child may experience symptoms differently. Symptoms may include, but are not limited to, the following:

· pain (sharp or dull) at the site of the tumor

· swelling (mass) and/or redness at the site of the tumor

· increased pain with activity or lifting

· limping

· decreased movement of the affected limb

The symptoms may have been present over a short period of time or may have been occurring for six months or more. Often, an injury brings a child into a medical facility, where an x-ray may indicate suspicious bone lesions. Usually, the child does not appear to be ill.