Spinal cord biopsy findings of anti‐aquaporin‐4 antibody‐negative recurrent longitudinal myelitis in a patient with sicca symptoms and hepatitis C viral infection

We describe the pathological features of a spinal cord biopsy from a 69‐year‐old woman with anti‐aquaporin‐4 antibody‐negative recurrent longitudinal myelitis. Spinal cord MRI showed T2 high‐intensity lesions with strong gadolinium enhancement, when episodes of sensory‐motor impairment were repeated. The radiological abnormality was corrected by corticosteroid administration, but improvement of the symptoms was minimal. Although the patient had sicca symptoms and fulfilled four of the diagnostic criteria for Sjögren syndrome, the diagnosis was excluded, because of infection with hepatitis C virus, an exclusion criterion of Sjögren syndrome. In the spinal cord lesions, necrotic changes affected both myelin and axons. Infiltrating lymphocytes were predominantly T‐cells. The proliferation of small vessels with hyalinization and concomitant occlusive change was remarkable. These pathological findings resembled those previously reported in Sjögren syndrome. Ultrastructurally, the endothelial cells of the small vessels showed features of activated cells and contained vesiculo‐tubular structures in the cytoplasm, indicating that increased blood‐brain barrier (BBB) permeability might contribute to pathogenesis. We speculated that increased BBB permeability and T‐cell entry in the spinal parenchyma triggered pathological reactions resulting in necrotic changes in the spinal cord. Obstruction of small vessels might add ischemic damage to the lesions. The clinical course and pathological findings indicated that damage progressed rapidly in the spinal cord and was irreversible. The lesions apparently differed from typical demyelination plaques. Faced with such spinal cord lesions, a preventive therapeutic approach is necessary to avoid attack‐associated disability.