The Use of Next-Generation Sequencing to Assist in the Diagnosis of Atypical Vasculitis

Vasculitis can be challenging to diagnose, especially when vessels of multiple sizes are affected and manifestations do not classically fit into defined rheumatic disease entities. We present the case of a 58-year-old Caucasian woman who presented with headache and altered mental status, with subsequent left-sided hemiparesis and hemispatial neglect eight days after a dental procedure. She was found to have extensive multi-focal ischemic infarctions secondary to vasculitis affecting multiple intracranial blood vessels. Subsequent imaging showed increasing involvement of intra-abdominal blood vessels. There was no evidence of endocarditis. Serologies for lupus and autoimmune rheumatologic diseases were unremarkable. Our suspicion was high for an infectious trigger of vasculitis. However, extensive conventional diagnostic testing, including multiple blood cultures and brain biopsy, did not reveal an underlying infectious etiology. The use of next-generation sequencing (NGS) of cell-free DNA from blood revealed the infectious pathogen <i>Prevotella melaninogenica</i>. Combining targeted anti-microbials with systemic steroids, plasmapheresis, and immune suppressant therapy, this case had a favorable outcome. The use of NGS can be useful in the diagnosis of atypical vasculitis.