SESSION TITLE: ILD Student/Resident Case Report Posters
SESSION TYPE: Medical Student/Resident Case Report
PRESENTED ON: Tuesday, October 28, 2014 at 01:30 PM - 02:30 PM
INTRODUCTION: Microscopic polyarteritis is a rare ANCA-associated vasculitis that typically manifests with renal and occasionally pulmonary symptoms. Here we describe an atypical pulmonary manifestation of this disease.
CASE PRESENTATION: A 64 year old Caucasian male with a history significant for smoking and asbestos exposure presented to the ED with acute hypoxemic respiratory failure. A CT thorax revealed a diffuse reticular pattern of interstitial lung disease with confluent regions of opacification, particularly near the periphery of the lungs, and a honeycomb appearance extending into the apices. PFTs demonstrated a restrictive pattern with severely reduced diffusion capacity. His oxygen requirements continued to increase during his hospitalization from 2L nasal cannula up to 60% on a non-rebreather. Concurrently, he had been found to have normal renal function just several weeks prior to admission, which had continued to deteriorate throughout his hospitalization. An extensive rheumatological workup was done demonstrating an ESR > 120 mm/hr and CRP 205.7 mg/L. p-ANCA was positive with a titer of 1:320, which was confirmed with positive myeloperoxidase (MPO) (78.4) and normal proteinase-3. A renal biopsy was eventually required secondary to worsening metabolic acidosis, which revealed ANCA associated necrotizing glomerulonephritis and vasculitis, consistent with microscopic polyarteritis (MPA). Treatment with plasmapheresis therapy was initiated.
DISCUSSION: Pulmonary fibrosis is a rare initial presentation of MPA, especially considering the rapid time frame within which this patients lung function declined. This case was further confounded by his significant exposure to smoking and asbestos. However, as his renal function rapidly deteriorated, the renal biopsy helped lead us to our diagnosis, the method in which most cases of MPA are diagnosed. There are currently no large studies describing the clinical manifestations of MPA. The pathophysiology of pulmonary fibrosis in MPA is not well understood, but according to (1), the anti-MPO antibodies may contribute via the generation of reactive oxygen species and upregulation of fibroblast proliferation. The pulmonary manifestations of MPA and Wegener's granulomatosis are similar clinically, with differentiation occurring primarily by the lack of granulomas in MPA as described by the Chapel Hill Consensus Conference criteria. The prognosis for patients with pulmonary fibrosis secondary to MPA is poor, with a median survival of 72 months.
CONCLUSIONS: Rapidly worsening pulmonary fibrosis, although uncommon, can be a presenting manifestation of a rare vasculitis like MPA. Our case reminds us of the importance of having a broad differential in mind and ruling out other causes of pulmonary fibrosis via an extensive workup to initiate appropriate treatment.
Reference #1: Guilpain et al. The oxidation induced by antimyeloperoxidase antibodies triggers fibrosis in microscopic polyangiitis. Eur Respir J 2011; 37: 1503-1513
DISCLOSURE: The following authors have nothing to disclose: Michael Kosters, Shalin Kothari, Tammer Ghaly, Amit Dhamoon
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