RESUMO
Below we highlight a rare case of anti-neutrophil cytoplasmic antibody (ANCA)-negative vasculitis, unique in its own right, as the diagnosis was hard to make and the respiratory decline rapid, with the patient going from a 23% fraction of inspired oxygen (FiO2) on admission to 100% FiO2 within four days for what was initially presumed to be community-acquired pneumonia. Precise data on the incidence or prevalence of ANCA-associated vasculitis are lacking. However, a 20-year population-based study in the United States found that, of 58 incident cases, 9% were ANCA-negative. We present the case of a 69-year-old Egyptian male with worsening shortness of breath who was found to have elevated inflammatory markers and an ANCA-negative panel and was later diagnosed with ANCA-negative vasculitis. By highlighting this case, we aim to increase awareness and point out the need to keep the disease high on the list of differential diagnoses in order to allow for timely intervention. Though there isn't a lot of data available on definitive treatment or the disease itself, there are studies that point to rituximab, cyclophosphamide, plasmapheresis, and hemodialysis as useful interventions for treatment.