What Is Your Diagnosis ?

A 67-year-old woman with no known primary malignancy, complained of generalized bone pain for 3
months. She appeared pale on physical examination with tenderness on deep palpation over the lumbar
spine. Examination of other systems was unremarkable. Laboratory investigations revealed normochromic
normocytic anaemia and raised ESR. Serum electrophoresis demonstrated the presence of abnormal
M-paraprotein
radiographs of the skull, ribs and femur were performed