<prompt> Commonest cause of skeletal metastasis isKidneyProstateBreastThyroid  <response>: C. i.e. Breast 1202 - CSDT 12th 450 - S. Das 5thMETASTATIC BONE TUMORS80 of these metastatic lesions are from primary carcinomas - particularly of the Breast, Prostate, lung kidney, thyroid pancreas or stomach in that order of frequency Breast or prostate metastasis either partly or solely osteoblastic OSSOPHILE TUMOURS shows predilection for metastasis in the bone eg Breast, Prostate, Kidney, Bronchus, and Thyroid OSSOPHOBE TUMOURS Do not show predilection for metastasis in the bone eg GIT, urinary bladder, genitalia etc Most common primary source of solitary skeletal metastasis at the time of first diagnosis is carcinoma of the kidney 1202 - CSDT 12th 