Paraneoplastic Neuromyelitis Optica Spectrum Disorder Associated With Lung Adenocarcinoma: A Case Report.

Neuromyelitis Optica spectrum disorder is an inflammatory demyelinating disease affecting the central nervous system (CNS), characterized by triad optic neuritis, transverse myelitis, and area postrema syndrome. Antibodies directed against aquaporin-4 (AQP-4), a water channel expressed on the astrocytic membrane, are supposed to play a pathogenic role and are detected in ~80% of cases. Clinical signs of Neuromyelitis Optica spectrum disorder (NMOSD) in elderly patients should arouse the suspicion of paraneoplastic etiology. In this article, we discussed a case of a 76-year-old woman with a 2-month history of confusion, dysarthria, and progressive bilateral leg weakness. A whole-body CT scan showed a neoformation of 5 cm in diameter in the median lobe infiltrating the mediastinal pleura. The tumor had already spread to both the upper and lower right lobes, parietal pleura, and multiple lymph nodes. Pleural cytology revealed adenocarcinoma cells. The brain MRI documented hyperintense alteration in fluid-attenuated inversion recovery (FLAIR) images, involving the anterior portion of the corpus callosum and the periependymal white matter surrounding the lateral ventricles, with mild contrast enhancement on the same areas and meningeal tissue. T2-weighted spinal cord MRI sequences showed extended signal hyperintensity from bulbo-cervical junction to D7 metamer, mainly interesting the central component and the gray matter. Cerebrospinal fluid analysis revealed no neoplastic cells. Serum AQP-4 immunoglobulin (IgG) antibodies were found. Meanwhile, the patient rapidly developed progressive paraparesis and decreased level of consciousness. High-dose intravenous methylprednisolone therapy was started but her conditions rapidly deteriorated. No other treatment was possible.