Paraneoplastic neuromyelitis optica spectrum disorder associated with breast cancer.

A 10-year-old girl with a past medical history significant for prematurity at 29 weeks, short bowel syndrome secondary to necrotizing enterocolitis, prior episodes of small intestinal bacterial overgrowth complicated by D-lactic acidosis, and gastric tube dependence presented to an emergency department with emesis, slurred speech, somnolence, and unsteady gait. Workup was initiated, and she was started on broad-spectrum antibiotics and transferred to our pediatric intensive care unit for further evaluation and treatment. Differential diagnosis on admission was broad, and, through thorough laboratory evaluation, imaging, and multiple subspecialty inputs, an unusual diagnosis was confirmed.