Excessive bone resorption in human plasmacytomas: direct induction by tumour cells in vivo.

We studied the bone resorption (BR) in 82 patients with overt plasmacytomas (PCT) by histomorphometry. All the solitary PCT and 90% of overt PCT in complete remission lacked excessive BR. In contrast, 73% of the 68 patients with active overt PCT had an excessive BR. This excessive BR was highly related to the presence of tumour cells within the bone sample. Indeed, 92% of patients with active PCT and tumour cells within the biopsy had an excessive BR. On the other hand, 70% of patients with active PCT but lacking tumour cells within the biopsy had normal BR.