[Anatomopathological aspects of giant cell tumors of the bone]

The morphological study of Giant Cell Tumors of Bone collected at the Orthopaedic Department of C.H.U. Cochin, with high resolution radiography of macroscopical samples added to topographical cytology allows to report the following facts: --Mononuclear cells have cytonuclear criteria between histiocyte and fibroblast cells, quite apart from Chondroblastoma and Chondromyxoid fibroma. Cytological transitions are observed between mononuclear and giant cells. --Osteoid formation is usually connected with the lysis or the blow-up of the neighbouring cortex. Without secondary changes, collagenisation is reduced. --A vascular network is appearing between the cortex and the tumor, factor of some radiological evolutions, those aspects being nearly similar to aneurysmal bone cyst. --The grading of the tumour has no valuable architectural support ; mitotic activity is equally of no value for the assesment of a recurrence. Nuclear analysis with granular clumping of chromatin, thickening of the nuclear rim and increase in size and number of nucleoli was only a help to identify sarcomas. The latter are primary-associated with quiescent-appearing lesions or merging on multiple tumoral sampling. Giant cell sarcoma, except fibroblastic-like forms, can keep a differenciated cytology with frequent amitosis. --Tumor polymorphism is warrant of some histological pitfalls ; the most rewarding territories for the analysis are in the long bones the upper epiphyseal areas. Whereas, the frequency of secondary changes enhance the additional value of topographical inprint cytology for a correct morphological appraisal.