Extraosseous spinal epidural plasmocytoma associated with multiple myeloma: Two case reports.

Background: Multiple myeloma is a malignant hematological disease characterized by proliferation of monoclonal plasma cells mainly in the bone marrow. Extraosseous epidural plasmacytoma associated with myeloma arises from lymphoid tissue in the epidural space without focal vertebral involvement, and is rare.

Case Summary: A 52-year-old woman was diagnosed with kappa subtype nonsecretory multiple myeloma and presented with bilateral arm weakness 11 mo after completing multiple courses of chemotherapy. Spinal magnetic resonance imaging (MRI) showed a posterior C7-T3 epidural mass with spinal cord compression. After five courses of chemotherapy, follow-up MRI showed resolution of cord compression. A 54-year-old man presented with paraplegia 15 mo after a diagnosis of IgD kappa subtype multiple myeloma and completing multiple courses of chemotherapy. He underwent Th11 and L1 laminectomies for tumor resection because MRI showed an epidural mass causing cord compression. His-topathologic examination was consistent with IgD multiple myeloma. The patients have currently survived for 33 mo and 19 mo, respectively.

Conclusion: Isolated extraosseous epidural plasmacytoma associated with multiple myeloma without bony involvement is difficult to diagnose by imaging. Definitive diagnosis requires pathological and immunohistochemical examination.