Aquaporin-4 antibody positive short transverse myelitis associated with breast cancer

Neuromyelitis optica spectrum disorder (NMOSD) is an inflammatory demyelinating disease of the central nervous system (CNS). A typical finding on spinal magnetic resonance imaging (MRI) of NMOSD is longitudinally extensive transverse myelitis (LETM). However, patients with NMOSD presenting with short-segment transverse myelitis (STM) during myelitis attacks associated with breast cancer are uncommon. We report a case of a 35-year-old woman with STM and left eye optic neuritis. The patient was positive for serum aquaporin-4 antibodies (AQP4-IgG), and a biopsy of the left breast showed invasive ductal carcinoma. The patient was diagnosed with NMOSD and breast malignancy. This is the first report of a patient with NMOSD whose spinal MRI showed STM and serum test showed that the patient's AQP4-IgG was positive and complicated by breast cancer. This case improves our understanding of the association between NMOSD and cancer and raises the question of whether it was a coincidental occurrence. It is important to search for extensive malignancies in patients presenting with atypical MRI or no reaction to traditional therapies.