GENERAL INFORMATION
High grade surface osteosarcoma is a type of high grade osteosarcoma that develops on the surface of the bone from the outer cortex.
There is none to minimal medullary involvement
The microscopic pathology is the same as a conventional osteosarcoma and it has the same high potential for metastasizing.
High grade surface osteosarcoma is the least common type of surface osteosarcoma (Parosteal and periosteal osteosarcomas are more common)
This is a very rare neoplasm and constitutes <1% of all osteosarcomas
CLINICAL PRESENTATION
Signs/Symptoms: Pain and/or swelling lasting from months to more than a year
Prevalence: Slight male predominance
Age: 2nd Decade is most common
Patients have ranged in age from 9 to 62 years
Sites: Femur (45%); Humerus (26%); Fibula (10%); Ulna are the most commonly reported sites
Usually arise from the diaphysis or metadiaphysis of the bone
RADIOGRAPHIC PRESENTATION
Plain X-Rays:
Broad based mass on surface of bone that is partially mineralized (fluffy calcifications/ossification in mass)
Appearance similar to periosteal osteosarcoma but usually with more ossification
Matrix mineralization is similar to conventional osteosarcoma with cloudlike opacities
Amount of mineralization varies
Codman's triangle/Malignant periosteal reaction may be present
Cortical erosion is usually evident
Medullary cavity is usually uninvolved
Plain X-Ray: High Grade Surface Osteosarcoma of Distal Tibia
GROSS PATHOLOGY
Tumors are bulky, lobulated masses
Have firm, soft, and hemorrhagic areas
Dense sclerosis typical of a parosteal osteosarcoma and significant amounts of cartilage typical of a periosteal osteosarcoma is not common
Cortex usually roughened and eroded
There may be small foci of intramedullary invasion
Gross Pathology of High Grade Surface Osteosarcoma of Distal Tibia
MICROSCOPIC PATHOLOGY
The pathology of a high grade surface osteosarcoma is indistinguishable from conventional medullary osteosarcoma
The lack of medullary involvement distinguishes this tumor from a conventional intramedullary osteosarcoma
It consists of high grade, anaplastic, pleomorphic spindle cells producing osteoid and immature bone that is deposited in a lace-like manner
Microscopic Pathology High Grade Surface Osteosarcoma
Differential Diagnosis of High Grade Surface Osteosarcoma
Parosteal Osteosarcoma
Dedifferentiated Parosteal Osteosarcoma
Periosteal Osteosarcoma
Intramedullary Osteosarcoma with large soft tissue component
(please refer to descriptions of parosteal and periosteal osteosarcoma)
Differentiating a high grade surface osteosarcoma from a conventional osteosarcoma is not important prognostically. They are essentially both treated in a similar manner as of 2008.
BIOLOGICAL BEHAVIOR
The biological behavior of a high grade surface osteosarcoma is similar to a conventional intramedullary osteosarcoma
There is a high risk for developing metastatic disease.
The most common site for developing metastases is the lungs.
The second most common site is other bones.
TREATMENT
The Treatment usually follows the same protocols as that used for conventional intramedullary osteosarcoma. Often COG (Children’s Oncology Group) protocols are employed.
Preoperative (induction) chemotherapy:
Adriamycin (doxorubicin)
Cisplatinum (cisplatin)
High Dose Methotrexate (HDMTX)
Ifosfamide/Etoposide in some regimens
(2 cycles and then surgery)
Surgery
Wide Surgical Resection/Limb Salvage for most patients
Amputation
Postoperative Chemotherapy
Usually 4 cycles postoperatively
Usually same medications as preoperative regimen although may be modified for various reasons such as a poor response to the preoperative chemotherapy medications
PROGNOSIS
Tumor has a great propensity for distant metastasis
Metastases occur in 80% of patients treated by excision alone
Lungs and other bones are most common sites
Overall 5-year survival rate depends on site, size, resectability, presence of metastasis. Survival is similar to conventional intramedullary osteosarcoma.
