DEFINITION AND PATHOGENESIS
- A relatively uncommon surface osteosarcoma with perhaps a slightly better prognosis than high grade intramedul-lary osteosarcoma
IMPORTANCE
Distinguishing these lesions from benign look-alikes is imperative (eg, periosteal chondroma)
CLINICAL FEATURES
- Pain (33%), swelling (33%), or pain and swelling (33%), for 1-24 months
RADIOLOGIC FEATURES
- Diaphyseal/metadiaphyseal
- Most often occurs in adolescents
- 85% about the knee
- Perpendicular spiculations, "saucer-shaped" to fusiform, eccentric, juxtacortical mass
- Bone scan with ? uptake
GROSS PATHOLOGY
- Fusiform mass in the juxtacortical tissue with rounded margins
- Bluish cartilage hue ? focal hemorrhage
HISTOLOGIC FEATURES
- Chondrosarcomatous appearance
DIFFERENTIAL CLINICOPATHOLOGIC DIAGNOSIS
- Parosteal chondrosarcoma
- Parosteal osteosarcoma
- Periostitis ossificans with a prominent cartilage component
- Parosteal chondroma
- Florid reactive periostitis ossificans
DISEASE COURSE AND TREATMENT
- Metastatic potential related to histologic grade
- Wide resection, chemotx
REFERENCES
Raymond AK: Surface osteosarcoma: Clin Orthop 270:140-8,1991.
Unni KK, Dahlin D, Beabout J: Periosteal osteosarcoma. Cancer 37:2466-75,1976.
Wold LE, Unni KK, Beabout J, Pritchard D: High grade surface osteosarcoma. Am J Surg Pathol 8:181-6,1984.
