Neuromyelitis Optica Spectrum Disorder with Interstitial Pneumonia and Marked HyperCKemia as an Initial Presentation: A Case Report and Literature Review.

Neuromyelitis optica spectrum disorder is an inflammatory disease of central nervous system. Autoantibodies against aquaporin 4 (anti-AQP4-ab) are often present in neuromyelitis optica spectrum disorder and have pathogenic effects on central nervous system. Aquaporin 4 is also expressed in peripheral organs, and some cases of anti-AQP4-ab-positive neuromyelitis optica spectrum disorder with peripheral organ involvement have recently been reported. Here, we report a unique case of anti-AQP4-ab-positive neuromyelitis optica spectrum disorder. A 58-year-old man was admitted with fever, interstitial pneumonia, and markedly increased serum-creatine kinase levels (up to 300,200 U/L). Skeletal muscle biopsy revealed rhabdomyolysis. Collagen and infectious diseases were excluded; therefore, adverse effects of prescription drugs were initially suspected. Clinical symptoms improved with steroid administration and discontinuation of all previously prescribed medications. However, bilateral vision loss, bilateral lower-limb muscle weakness, and bilateral lower-limb sensory disturbances appeared later, and fever and increased serum-creatine kinase levels recurred. The patient was diagnosed with neuromyelitis optica spectrum disorder with peripheral organ (lung and skeletal muscles) involvement based on magnetic resonance imaging findings and serum anti-AQP4-ab positivity. Our case demonstrates that interstitial pneumonia and rhabdomyolysis can be the initial symptoms and indicators of the relapse of anti-AQP4-ab-positive neuromyelitis optica spectrum disorder, and skeletal muscle involvement can lead to markedly elevated creatine kinase levels.