GIANT-CELL RICH PAROSTEAL OSTEOSARCOMA

A parosteal osteosarcoma of the distal femur with a typical radiograph ic and macroscopic appearance is reported, On histology the tumour was dominated by large numbers of osteoclast-like giant cells in a fibro- osseous background and islands of immature bone, Most of the neoplasti c bone lacked osteoblastic rimming, There was no spatial relationship between the giant cells and areas of haemorrhage, Signs of 'dedifferen tiation' were lacking, Cytogenetic a analysis revealed telomeric assoc iations which are frequently found in giant cell tumours of bone, Paro steal osteosarcoma may, on histological appearances, hardly be recogni zable as malignant, In addition, unusual changes such as abundant gian t cells may be misleading in the absence of clinico-pathological corre lation.