Synopsis
parosteal osteosarcoma
large numbers of osteoclast-like giant cells
fibro-osseous background
islands of immature bone
neoplastic bone lacking osteoblastic rimming
no spatial relationship between the giant cells and areas of haemorrhage
Cytogenetics
Differential diagnosis
Parosteal osteosarcoma may, on histological appearances, hardly be recognizable as malignant. In addition, unusual changes such as abundant giant cells may be misleading in the absence of clinico-pathological correlation.
References
Giant cell rich parosteal osteosarcoma. Sciot R, Samson I, Dal Cin P, Lateur L, van Damme B, van den Berghe H, Desmet V. Histopathology. 1995 Jul;27(1):51-5. PMID: 7557906