Clues to the appropriate malignant diagnosis include a more aggressive, infiltrative lesion on imaging studies, and the presence of nuclear atypia, atypical mitoses, and/or malignant osteoid
production on histologic examination.
There is abundant cartilage with focal endochondral ossification and trabeculae bone formation without malignant osteoid
Osteosarcoma is a malignant primary tumor of bone consisting of malignant stroma with evidence of malignant osteoid
, bone and cartilage formation (Spjut et al., 1971).
Presence of malignant osteoid
showing variable mineralization interspersed among the tumor cells.
In non-productive osteoblastic osteosarcomas, areas of malignant osteoid
tissue might be very difficult to found (5,7).
The diagnosis of cutaneous osteosarcoma is made on the basis of the histologic Finding of disorderly dermal deposition of malignant osteoid
and exclusion of a bony primary osteosarcoma and/or metastases.
Moreover, the regularly spaced spicules of woven bone seen in FD are not present in osteosarcoma, where malignant osteoid
is often deposited in broader and irregular trabeculae.