Primary amyloidosis with peripheral neuropathy and signs of motor neuron disease.

A 51-year-old man had primary amyloidosis, with typical amyloid neuropathy and signs of motor neuron disease, including widespread fasciculation in limb muscles, tongue atrophy and fasciculation, swallowing and chewing difficulty, symmetric hyperreflexia, and bilateral Hoffmann's signs. Fasciculations, fibrillations, and positive sharp waves were found in electromyography of all muscles tested. Motor nerve conduction velocities were moderately slow. Lambda chains were detected in serum and CSF. Amyloid was found in sural nerve biopsy. This combination of amyloid neuropathy and features of amyotrophic lateral sclerosis is related to the motor neuron disease of plasma cell dyscrasias.