An Interesting Case of Microscopic Polyangiitis Presenting as Rapidly Progressive Pulmonary Fibrosis.

SESSION TITLE: Miscellaneous Student/Resident CasesSESSION TYPE: Medical Student/Resident Case ReportPRESENTED ON: Tuesday, October 28, 2014 at 04:30 PM - 05:30 PMINTRODUCTION: Microscopic polyangitis (MPA) is part of a spectrum of vasculitic diseases affecting small to medium sized vessels causing rapid renal failure secondary to glomerulonephritis, non-scarring recurring rash and inflammatory changes in the lungs ranging from diffuse alveolar hemorrhage to fibrosis.CASE PRESENTATION: 63 year old Caucasian male presented with acute on chronic hypoxic respiratory failure. Three months ago he was diagnosed with COPD (unconfirmed) and placed on home oxygen. CT chest at that time did not show any obvious abnormalities. Over the past three months his shortness of breath was stable on oxygen. He also noted fevers, night sweats, weight loss of thirty pounds and recurring rash on his lower extremities during this time period. On hospital admission, he was noted to have diffuse velcro crackles on lung exam and acute renal failure with urinalysis positive for hematuria on labs. Chest radiograph was negative for infiltrates, however his symptoms far outweighed his presentation, thus a CT scan was ordered showing honeycombing of both lungs with increased fibrosis in the periphery and bronchial tracking, a dramatic progression of fibrosis. Initially, the differential was focused on interstitial lung disease as his pulmonary function test demonstrated restrictive disease with a severely reduced DLCO. Due to the rapid nature and multiple organ involvement, a rheumatologic workup was done, yielding a positive p-ANCA (anti-neutrophil cytoplasmic antibody) and anti-myeloperoxidase antibody. Further testing in the form of renal biopsy was done for worsening renal failure providing the diagnosis of microscopic polyangitis. Patient was treated with pulse dose steroids and cytostatic therapy which improved his pulmonary symptoms.DISCUSSION: MPA may be p-ANCA positive (40-50%), c-Anca positive (20-40%) and/or anti-myeloperoxidase antibody positive (50%). A negative ANCA, does not rule out vasculitis, especially if typical organ systems are involved. Other differentials of p-ANCA include primary pauciimmune necrotizing cresentric glomerulonephritis (50%) and Churg-Strauss syndrome (35%). Definitive diagnosis can be made from biopsy of the affected tissue. In the lungs, MPA can present as diffuse alveolar hemorrhage or pulmonary fibrosis. This fibrosis can be mistaken for Interstitial lung disease (ILD), which has no effective treatment. In contrast, MPA responds well to corticosteroids and cytostatics and increases the total survival rate up to 91%1.CONCLUSIONS: MPA survival rate depends on the severity of lung lesions whereas renal problems had no appreciable effect on life prognosis1. Thus pulmonary fibrosis (and hemorrhage) should be evaluated for MPA for possible effective therapy.Reference #1: Zakharova EV, Iakovlev VN, Vinogradova OV, Sheikh ZhV, Zhidkova NV, Alekseev VG. ANCA-associated vasculitis affecting lungs and kidneys: clinical and morphological characteristic, treatment, outcomes. Klin Med (Mosk). 2013;91(7):38-43.

DISCLOSURE: The following authors have nothing to disclose: Meghan Rane, Emerald Banas, Aakash Aggarwal, Michael IannuzziNo Product/Research Disclosure Information.