[A case of neuromyelitis optica associated with pulmonary Mycobacterium avium complex disease]

A 62-year-old woman suffering from pulmonary Mycobacterium avium complex (MAC) disease was admitted to our hospital with fever, visual impairment, and lower limb weakness. MRI detected lesions in the optic chiasm and spinal cord extending the length of 6 vertebrae. The anti-aquaporin 4 (AQP4) antibody titer determined by ELISA was elevated to 8.3 IU/l. On the basis of these findings, the patient was diagnosed as having neuromyelitis optica (NMO), when chest CT also demonstrated exacerbation of pulmonary lesions. Methylprednisolone pulse therapy and double-filtered plasma exchange ameliorated the symptoms, and the EDSS score improved from 8.5 to 6.5. Six months later, visual impairment recurred, although ELISA showed that the anti-AQP4 antibody titer had become undetectable. Also, the CSF interleukin-6 (IL-6) level was elevated to 34.8 pg/ml. There have been few reports of NMO associated with pulmonary MAC disease. An increase of IL-6 is considered to exacerbate the clinical picture of NMO, whereas it may suppress progression of the pulmonary MAC disease. Exacerbation of the pulmonary MAC disease and the following internal counteraction with IL-6 may have resulted in a NMO relapse. The present patient was therefore administered eculizumab but not satralizumab, a humanized anti-IL-6 receptor antibody, for prevention of NMO recurrence.