PULMONARY FIBROSIS AND FOOT DROP: A CASE OF MICROSCOPIC POLYANGIITIS FOLLOWING IDIOPATHIC PULMONARY FIBROSIS (IPF) DIAGNOSIS

Abstract

SESSION TITLE: Tuesday Fellows Case Report Posters SESSION TYPE: Fellow Case Report Posters PRESENTED ON: 10/22/2019 01:00 PM - 02:00 PM INTRODUCTION: Pulmonary fibrosis (PF) associated with antineutrophil cytoplasmic antibody (ANCA) is a rare but described diagnosis, with some patients meeting criteria for microscopic polyangiits (MPA). Conversion to ANCA-MPO positivity and MPA with vasculitic findings can lag behind the initial diagnosis of PF. CASE PRESENTATION: We present a case of a 75 year old man with a history of a bladder tumor and PF who presented to clinic with 6 months of worsening cough, fatigue, weight loss and neuropathy. His PF was initially diagnosed 1 year prior and considered idiopathic. At that time he had an abnormal CT chest, significantly decreased DLCO, positive ANA, and normal inflammatory markers. Approximately one year later he complained of progressive cough, fatigue and weight loss, and was hospitalized for anemia and leukocytosis with an unrevealing workup. He was prescribed antibiotics for Aeromonas pneumonia. He then presented to clinic where his physical exam was notable for mild tachypnea, left foot drop and right hand numbness. PFTs revealed a significant decline in vital capacity and DLCO. He was admitted and workup revealed CT chest with new infiltrates, an elevated ANA, elevated ESR/CRP and elevated ferritin. ANCA- MPO was positive. He underwent sural nerve and skeletal muscle biopsy which showed necrotizing vasculitis with fibrinoid necrosis, and he was started on high dose steroids. He improved and was discharged to home to start rituximab infusion as outpatient. DISCUSSION: Pulmonary fibrosis associated with ANCA vasculitis is rare and typically associated with MPA. Case studies have placed prevalence of ANCA positive PF from 2-14% of PF patients initially considered idiopathic. Of those patients, about half had seroconversion/develop MPA after initial PF diagnosis. CT imaging for ANCA-MPO patients may be indistinguishable IPF on imaging with a UIP pattern of fibrosis. The pathogenesis of ANCA-MPO associated fibrosis is unclear, but possibly related to recurrent alveolar hemorrhage, direct damage from neutrophils or ANCA induced by a pulmonary inflammatory process. ANCA positive PF patients are more likely to be treated with steroids and immunosuppression including cyclophosphamide or ritxumab. These treatments may be useful in early disease, but likely have limited efficacy in late stage/fibrotic disease. Patients with MPA and PF have a clinical progression similar to patients with IPF, with worse survival compared to MPA patients without PF. Not all PF patients with ANCA-MPO positivity develop systemic vasculitis, however, clinicians should be on alert for signs and symptoms of systemic disease as early intervention could prevent progression. CONCLUSIONS: It is important to consider ANCA vasculitis both at the time of diagnosis of pulmonary fibrosis and later in a patient’s clinical course. Reference #1: Casares MF, Gonzales MF, Caputo F, Bottinelli Y, Zamboni M. Microscopic polyangiitis associated with pulmonary fibrosis. Clin Rheumatol 2015 34:1273-1277. Reference #2: Kagiyama N, Takayanagi N, Kanauchi T, et al. Antineutrophil cytoplasmic antibody-positive conversion and microscopic polyangiitis development in patients with idiopathic pulmonary fibrosis.BMJ Open Respiratory Research 2015;2:e000058. Reference #3: Tzelepis GE, Kokosi M, Tzioufas A, et al. Prevalence and outcome of pulmonary fibrosis in microscopic polyangiitis. Eur Resp J 2010; 36:116-121 DISCLOSURES: No relevant relationships by Samantha Parker, source=Web Response