1. H Nèji, H Abid, A Mâalej, S Haddar, R Akrout*, M Ezzeddine*, S Baklouti*, Z Mnif**, J Mnif Imaging department Habib Bourguiba Hospital, *Rheumatology department Hedi Chaker Hospital, ** Imaging department Hedi Chaker Hospital, Majida Boulila Avenue, 3029 Sfax, Tunisia NR19

2. Introduction: Myeloma is a plasma cell dyscrasia that preferentially touches the axial skeleton. It can extend into the spinal canal and cause spinal cord compression. The aim of this work is to emphasize how CT and MRI can contribute to the assessment of this extension.

3. Materials and methods: This is a retrospective study in which we were interested in 68 patients in whom the diagnosis of myeloma was certain. Twelve among these 68 patients had extension into the spinal canal. They were 6 women and 6 men with a mean age of 63years. All patients had X-ray examinations. 3 patients underwent a spine computed tomography (CT). 9 patients underwent a spine MRI. 9 patients had thoracic and lumbar spine aches.

4. Results: 5 among the 12 patients had clinical signs of medullary compression. 2 among them had no detectable lesion on the X-ray examination of the spine. CT and MRI showed bone lesions of the spine in all cases. Epidural extension was found in cervical spine in 3 cases, dorsal spine in 8 cases and lumbar spine in 1 case. Epidural extension from posterior arch lesions was found in 5 cases, from the vertebral body in 5 cases. Primitive epidural location was found in 2 cases.

5. A sixty-year-old woman Back pain Clinical signs of meullary compression Immunoelectrophoresis : normal MRI : lesion of the posterior arch and medullary compression. Surgical biopsy: IgG class myeloma Sagittal T1WI SagittaleT2WI Contrast T1WI Case n°1 :

6. A sixty-four-year-old woman Back pain Medullary MRI and CT: osteolytic lesion of the fifth dorsal vertebra with development of an intra- canalar mass. Immunoelectrophoresis: Kappa light chain myeloma Sagittal T2 WI Enhanced-CT of the dorsal spine Case n°2:

7. Sagittal T2WI A 72-year-old woman Altération de l’état général Back pain Clinical signs of medullary compression Spine MRI : vertebral compaction with epidural mass squeezing the spinal cord. IEPP : kappa light chain myeloma Case n°3

8. Discussion Multiple myeloma is a malignant disease of plasma cells in the bone marrow. It accounts for about 1% of all cancers and 10 % of hematologic malignancies. The number of plasma cells in the bone marrow is increased and osteoclasts are activated in the region of plasma cell foci. The cell proliferation, then, extends to the epidural space causing spine canal narrowing and spine cord compression. This complication occurs in 5 % of myeloma cases.

9. Discussion In myeloma, MRI is particularly recomended to : Evaluate the extension to the axial skeleton Detect lesions non-detected on X-ray examinations Confirm the diagnosis of solitary plasmocytoma Make the diagnosis of medullary compression

10. Discussion Bony involvement in myeloma is frequently of a lytic nature with frequent extra-osseous spreads. Spinal cord compression is usually caused by primary involvement of the vertebral body with tumor extension into the adjacent spinal canal. Imaging modalities show in these cases large, lytic bone lesions or collapse of the vertebral body in the corresponding segment.

11. Discussion Extramedullary multiple myeloma is very rare, comprising less than 5% of all plasma cell neoplasms. Few cases have been reported in the literature. In these cases, there is no evidence of vertebral body destruction or collapse. X-ray and CT examinations are usually normal. Only the MRI MRI can confirm the presence of an epidural mass. Epidural lesions without osseous destruction can be explained either by the extension of para-spinal lymph node into the inter- vertebral foramen or by the development from the lymphoid tissue present in the epidural space.

12. Discussion In case of epidural locations without bone lesions, many diagnoses can be discussed such as : Primitive mild or malignant tumours (lipoma, liposarcoma) Metastases Locations of lymphoma Locations of leukemia

13. Conclusion Spinal cord compression is a serious complication of multiple myeloma. It often results from the extension of bone lesions of the vertebral body. Epidural location without vertebral destruction or collapse is rare. MRI is the best imaging modality to confirm the medullary compression.