Abstract Introduction Autoimmune disorders including connective tissue diseases (CTD) and the vasculitides can lead to isolated interstitial pneumonia (IP) absent other characteristic multisystem manifestations. We present a case of an unexplained IP with autoimmune features that presented years later with pulmonary-renal syndrome (PRS) due to an anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). Case Presentation A 70 years-old man with gout and immune thrombocytopenia was seen by Pulmonology for chronic dyspnea and cough. He is a never cigarette smoker, but described significant second-hand smoke exposure, as well as daily marijuana smoking. Chest radiograph showed interstitial densities and computed tomography (CT) showed subpleural reticular opacities with traction bronchiectasis as well as uniform basilar ground glass opacities. Pulmonary function tests (PFTs) showed moderate restrictive impairment (Total Lung Capacity 4.60 liters, 60% predicted) with severely reduced diffusing capacity (DLCO 7.25 mL/min/mmHg, 23% predicted). Laboratory work-up was significant for positive antinuclear antibodies (ANA) (titer 1:10,240, homogenous pattern), elevated C-reactive protein (39 mg/dL). Other autoimmune serologies including ANCA were negative. Hypersensitivity pneumonitis panel was negative. Symptoms, lung function, and imaging were stable over several years and he was ultimately lost to follow up. Eight years after initial consultation, he developed progressive kidney disease with hematuria then was hospitalized with acute renal and respiratory failure. CT showed progressed basilar predominant reticular opacities and cystic changes with traction bronchiectasis, and upper lobe mixed ground glass and interstitial opacities. Urine studies were suggestive of glomerulonephritis, hemoglobin was decreased from baseline 12 to 9 mg/dL. ANA was marginal (titer 1:80), p-ANCA positive (titer 1:640), anti-myeloperoxidase (MPO) antibody was positive (485 units), anti-proteinase 3 antibody was negative, complement C3 was low (55 mg/L), and anti-glomerular basement membrane antibody negative. He started intermittent hemodialysis and underwent renal biopsy showing diffuse crescentic necrotizing glomerulonephritis with frank vasculitis. Clinical data most supported a diagnosis of microscopic polyangiitis (MPA), a small-vessel AAV. He was treated with high dose steroids followed by Rituximab. Conclusion This case highlights a patient with an IP that later developed PRS due to an AAV. ANCA positivity, particularly anti-MPO, is correlated with pulmonary fibrosis (PF), with or without systemic vasculitis. In published case series, there is often substantial delay between onset of PF and development of ANCA positivity and manifestations of vasculitis. This case adds to evidence linking IP and PF with AAV and demonstrates the importance of index of suspicion for ANCA in the care of the patient with ILD. This abstract is funded by: None
Yenepalli et al. (Fri,) studied this question.
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