Amyloidoma of a spinal root.

A unique case of amyloidoma presenting as a dumbbell-shaped tumor of a spinal root without bony erosion is described. Amyloid was also present in the facial nerve. DNA analysis for transthyretin was negative. Isolated amyloid fibers contained lambda light chains, and although plasma and urine immunoelectrophoresis performed by immunofixation was normal, it is possible the tumor may have been derived from an isolated plasmacytoma.