Sensory-motor polyradiculoneuropathy as the first manifestation of sternum bone plasmacytoma only revealed by bone scintigraphy.

Bone plasmacytoma is a rare plasma cell neoplasm that can present with a polyradiculoneuropathy. A 57-year-old man presented with 2-month history of progressive weakness and numbness of both legs. Neurological examination showed symmetric distal weakness, reduced vibration senses in limbs and areflexia. CSF had high protein content. Electrophysiological evaluation revealed a demyelinating sensory-motor polyneuropathy. IgG-λ paraprotein was present in serum. Full skeletal survey, spinal MRI and body CT-scan were normal. 99mTc-methylene-dyphosphonate scintigraphy (99mTc-MDP) revealed a solitary accumulation in the sternum. Biopsy of the lesion demonstrated a plasmacytoma. We emphasize that 99mTc-MDP scintigraphy can be a useful screening procedure for patients with polyradiculoneuropathy and occult bone plasmacytoma.