Paraneoplastic AQP4-IgG-Seropositive Neuromyelitis Optica Spectrum Disorder Associated With Teratoma: A Case Report and Literature Review.

OBJECTIVES: To assess a case of paraneoplastic aquaporin-4 (AQP4)-immunoglobulin G (IgG)-seropositive neuromyelitis optica spectrum disorder (NMOSD) associated with teratoma and determine whether it is a paraneoplastic neurologic disorder. METHODS: A single case study and literature review of 5 cases. RESULTS: A 27-year-old woman presented with diplopia, facial nerve palsy, paraplegia, sensory dysfunction of lower limbs, dysuria, nausea, and vomiting. Spinal cord MRI detected an extensive longitudinal lesion in the spinal cord, and brain MRI detected abnormal lesions in the right cerebral peduncle and tegmentum of the pons. CSF analysis revealed positive oligoclonal IgG bands (OCBs). The patient tested positive for AQP4-IgG, confirming a diagnosis of NMOSD. An abdominal CT scan detected an ovarian tumor. After steroid therapy and tumor removal, the patient progressively improved, with only mild sensory dysfunction. Histopathologic analysis of the tumor revealed a teratoma and the presence of glial fibrillary acidic protein (GFAP)+ neural tissue with AQP4 immunoreactivity, accompanied by lymphocyte infiltration. Including the present case, there have been 6 reported cases of AQP4-IgG-seropositive NMOSD associated with ovarian teratoma (mean onset age, 32.7 years). Of these patients, 5 (83%) presented with nausea and/or vomiting, positive OCB, and dorsal brainstem involvement. Pathologic analyses of the teratoma were available in 5 cases, including the present case, revealing neural tissue with AQP4 immunoreactivity and lymphocyte infiltration in all cases. CONCLUSIONS: This study suggests that ovarian teratoma may trigger the development of AQP4-IgG-seropositive NMOSD. Further studies are needed to elucidate the pathogenesis of teratoma-associated NMOSD.