Extraosseous multiple myeloma mimicking spinal epidural metastasis.

A 42-year-old man presented with a one-month history of upper back pain and a two-week history of progressive spastic paraparesis. Thoracic spinal MRI showed an epidural mass with spinal cord compression at T6-8 but no bony involvement. The patient underwent T6-8 laminectomy for decompression. Lumbosacral MRI and CT scans revealed bony abnormalities on the sacrum and left posterior iliac bone. Immunohistochemical studies confirmed the diagnosis of multiple myeloma (MM). Thus, this patient suffered from extraosseous MM without adjacent bony involvement or distant skeletal involvement.