Multiple myeloma is the commonest of all primary malignant bone tumour arises from the plasma cells of the bone marrow.
Clinical Features:
i)                  Aged 45-65 years                  Women > Men.
ii)               Weakness
iii)            Backache
iv)            Bone pain
v)               Pathological fracture
vi)            Anaemia due to red marrow function
vii)         Thrust, polyuria, abdominal pain due to hyper calcaemia
viii)      Infection due to decreased antibody
ix)            S/S or renal dysfunction, spinal cord or root compression.

Investigations:
1.      Blood- decreased Hb%, increased ESR, increased Serum creatinine, increased scrum calcium.
2.      Urine- Bencejones protein-present
3.      X-ray-        i)     Generalized ostecoparosis
                             ii)   Vertebral compression fracture
                             iii)  Multiple punched out-defects with soft margin in the skull, pelvis, proximal femur and vartebra.
4.      Sternal puncture- show plasma cytosis with typical myeloma cells.

Pathology:
At operation, the affected bone is soft and crumbly. The typical microscopic picture is of sheels of plasmacytes with a large ecentric mucleus containing a spoke like arrangement of chromatin.

Prognosis
The tumour is uniformly fatal, through its progress can often be checked for several years.

Treatment:
i.                   Pain control
ii.                Treatment of pathological fracture
iii.             Correction of fluid balance and hypercalcaemia
iv.             Perioperative antibiotic
·       The tumour foci respond to radiotherapy for while and pain is well relived.
·       Chemotherapy- Malphan together with prednisolone can be given. Malphan in conjunction with doxorubicin, curmastine and cyclophosphamide also can be given.
·       Fractures are best treated with internal fixation and packing of cavitics with methylmethacrylate cement. Spinal fractures need immedicate stabilization either by effective bracing or by internal fixation.