[Antineuronal antibody in carcinomatous neuropathy].

A seventy-year-old woman was admitted to the hospital because of paresthesias and progressive weakness of the extremities. Ten months previously, tightness in the thighs and numbness in the fingers developed, with subsequent tingling sensations of the hands and feet. Three months before entry, she had difficulty in walking because of severe paresthesias in the extremities. She was found to have an abnormal mass in a X-ray film of the chest, and transferred to our hospital. Neurological examination showed generalized hyporeflexia, marked loss of deep and discriminative sensations in the distal portion of the limbs, positive Romberg sign and severely ataxic gait. Cerebellar sign was negative. Cytologic examination of a transbronchial lung biopsy disclosed small cell carcinoma of the lung. A sural nerve biopsy showed severe loss of myelinated fibers accompanied by axonal degeneration of residual fibers. Immunohistochemically antineuronal antibody was found in the serum but not in the CSF, which reacted to nuclei and cytoplasm of the dorsal root ganglion neurons as well as Purkinje cells. Titers of this autoantibody in the serum were markedly reduced after chemotherapy and irradiation. Western blot analysis demonstrated that autoantibody in the serum recognized neuronal antigen with single band at 38 kd. Pathogenesis of carcinomatous neuropathy is still unexplained, but the findings here presented have given rise to the speculation that antineuronal antibody may be a contributory factor in carcinomatous neuropathy.