ANCA Negative Vasculitis Presenting with Interstitial Lung Disease and Pancytopenia

Abstract

Introduction: MPA (or microscopic polyarteritis) is clinically described as patients with exclusively nongranulomatous small vessel vasculitis involving the upper or lower respiratory tract (e.g., alveolar capillaritis). The most common manifestation of MPA is necrotizing glomerulonephritis and/or pulmonary capillaritis. Serologically, more than 90% of MPA patients have a positive antineutrophil cytoplasmic antibodies (ANCA). There have been selective case reports documenting pancytopenia associated with vasculitis. Case: Here, we discuss a 56 year old female patient who presented with pancytopenia, and was found to have biopsy-proven small vessel vasculitis with negative ANCA. She presented with 5-6 weeks of worsening generalized fatigue, cough with hemoptysis, intermittent fever, and shortness of breath on exertion and weight loss of 8lbs over this time. On presentation, she was febrile (102F) and found to have pancytopenia, with normal kidney function. She was admitted to the Intensive Care Unit for a presumed viral illness and underwent a bone marrow biopsy for evaluation of pancytopenia. Further imaging with computerized tomography (CT) scan demonstrated ground glass haziness. Bone marrow biopsy revealed normal results. She was discharged with the diagnosis of a pancytopenic viral illness. She returned 4 weeks later with worsening of her symptoms. CT chest showed significant interval changes compared to previous CT with bilateral ground glass opacities. Lung biopsy was performed which showed small vessel vasculitis. Repeat CT chest following steroid treatment demonstrated significant improvement.  Discussion: To our knowledge, this is the first reported case of pancytopenia in small vessel vasculitis not associated with lupus. In cases of MPA, 96% are ANCA positive. However, this patient fits into the criteria of ANCA-negative vasculitis. Although ILD is an uncommon presentation of MPA, there have been an increasing number of cases citing association of vasculitis with ILD. In conclusion, vasculitis associated with pancytopenia continues to be poorly understood. ANCA negativity at the time of presentation can give a false sense of security and delay treatment.