[Cytologic study of giant cell tumors. Electron microscopy. Cyto-enzymology].

A cyto-enzymologic study of giant cells tumor revealed a high acid phosphatase activity in multi-nuclear cells (as in osteoclasts) and a very low alcaline phosphatase and peroxydase activity. Acid phosphatase was located in lysosom which were concentrated in definite cytoplasmic areas. The blood rate of this enzyme should be raised if it were excreted by the cells. Therefore a study of acid phosphatase blood rate could reinforce a diagnosis based on X-rays and a raising rate after surgery could help for early detection of recurrences.