Case 15
An 18-year-old male University of Florida student presented at the student infirmary with an intermittently tender mass on the posterior aspect of the mid-leg.
A: Lateral radiograph of the leg. There is a crater-like radiolucency on the surface of the posterior cortex. A portion of the crater is in the posterior cortex itself while the majority is bounded by the mature Codman triangles of reactive bone.
B: Magnification of the radiograph. Within the crater there is a cloudy amorphus area of nonstress oriented ossification. There is also increased density in the medullary canal deep to the endosteal aspect of the posterior tibal cortex.
C: Regional isotope scan. There is intense increased uptake well beyond the radiographic extent of the lesion. This supports the impression that the cloudy amorphus mineralization is active immature ossification.
The differential diagnosis included a periosteal chondroma, periosteal osteosarcoma, as well as other aggressive surface lesions. The isotope scan however suggested a more extensive and aggressive lesion.
An excisional biopsy of the lesion and underlying posterior cortex of the tibia was done.
D: The external surface of the biopsy specimen. The surface of the soft tissue component was covered with non-reactive normal tissue denoting a wide margin at this point.
E: Sagittal surface of the bissected biospy specimen. The radiolucent crater was filled with a vascular soft spongy tissue with several small blood-filled cavities. There was no apparent invasion of the underlying cortex.
F: A low power field from the interior of the crater. The field is composed of hyperchromatic, pleomorphic spindle cells. In the center of the field is a prominent area where the stromal cells are embedded in lacey osteoid. There are several similar areas throughout the field. This accounts for the cloudy amorphous ossification seen radiographically and the intense isotope uptake.
G: A low power field from the edge of the crater. The majority of the field is composed of similar stromal cells but there is no formation of osteoid in this field.
H: Medium power from the central area of the lesion. In this field, particularly in the upper right hand corner, there is again significant neolastic osteoid about the stromal cells.
I: High power view from the same field. The upper central portion of the field shows the signature lacy newly mineralizing osteoid of classic osteosarcoma. At this magnification the marked cellular atypia (pleomorphism, hyperchromatic nucleii, high cell to matrix ratio) of a high grade sarcoma can be appreciated.
This is a classic osteosarcoma arising from the cortical surface of the tibia. It, despite its location, lacks the prominent cartilaginous component of a true periosteal osteosarcoma.
Diagnosis: Osteosarcoma.
With involvement of the tibia and extension into adjacent soft parts it is Stage IIB.
The patient recieved 4 cycles of adriamycin with a satisfactory response. Because of the extensive isotope uptake well beyond the limits of the excisional biopsy, a much more extensive wide resection of the tibial shaft was then done to achieve a wide margin. The defect was reconstructed with two conventional fibular autogenous cortical bone grafts.
AP radiograph immediately post-operatively.
AP radiograph at eighteen months. After graft union, there were two episodes of fatigue fractures through the grafts despite prolonged protection with orthoses. Treated with external immobilization only, all fractures healed.
AP radiograph at seven years. Gradually the grafts hypertrophied and the patient resumed guarded activity protected by orthoses.
AP radiograph at 20 years. However, at about ten years he had resumed his previous vigorous life style with no further complications.
Anterior view of the legs at 20 years.
Posterior view of the legs at 20 years.
Unrestricted activities at 20 years.
Activities at 20 years.
An 18-year-old male University of Florida student presented at the student infirmary with an intermittently tender mass on the posterior aspect of the mid-leg.
