Neuropathy with predominant small fiber involvement associated with abnormal anti-MAG titer.

We describe a patient with painful neuropathy associated with an abnormal anti-MAG titer in which predominant involvement of intra-epidermal nerve fiber was documented. Electrophysiological studies revealed low-borderline amplitude of sensory and compound motor action potentials registering from lower limbs and normal conduction velocity. Sural nerve biopsy disclosed only a slight loss of myelinated fiber. Skin biopsy performed at the proximal thigh and at the distal leg was consistent with a non-length-dependent small fiber neuropathy. It is likely that in this case anti-MAG antibodies played a role in the pathogenesis of small fiber neuropathy.