The serum acid phosphatase value was examined in nine patients with giant c
ell tumour of bone. Five showed a high level of acid phosphatase, which fel
l to within normal limits after surgery. Although the remaining four patien
ts showed a normal acid phosphatase level before surgery, the postoperative
acid phosphatase level was lower than the preoperative level in each case.
Therefore, it is strongly suggested that serum acid phosphatase is a usefu
l tumour marker in diagnosing giant cell tumour of bone as well as in evalu
ating the efficacy of treatment.