AB0631\u2005INTERSTITIAL LUNG DISEASE – A RARE MANIFESTATION OF MICROSCOPIC POLYANGIITIS

Abstract

Background: Interstitial lung diseases (ILD) are a group of diffuse inflammatory and/or fibrotic lung disorders with similar clinical, radiologic and histopathologic features. The coexistence of ILD and aNCA-associated vasculitis has been reported in case reports and small case series. Objectives: The aim of this study was to assess the prevalence, clinical and radiological characteristics of ILD in MPA patients admitted to the Rheumatology Department of our hospital. Methods: This retrospective single center cohort study included 102 patients diagnosed with MPA according to CHCC 2012 and EMA algorithm. We assessed Birmingham Vasculitis activity Score (BVAS) at disease onset and VDI (Vasculitis Damage index) at the end of the follow up in each patient. ANCA type and titer were assessed by enzyme-linked immunosorbent assay (ELISA). The results of repeated high resolution computed tomography (HRCT) of the chest were analyzed and interstitial changes (focal ground-glass opacity, reticular changes, honeycombing, traction bronchiectasis) were classified in four patterns: non-specific interstitial pneumonia (NSIP), typical interstitial pneumonia, possible interstitial pneumonia, and “inconsistent” usual interstitial pneumonia (UIP). Results: ILD-features on HRCT was found in 11 (11.8%) of 102 patients with MPA. Their median age was 55 [53; 63] years. All of them were aNCA-positive (Table 1). In 5 cases interstitial pneumonia was the first and the sole manifestation that preceded for the occurrence of overt systemic vasculitis for a median of 3 years. The radiologic patterns included non-specific interstitial pneumonia in 5 cases, usual interstitial pneumonia in 3 cases and unclassifiable interstitial pneumonia in 3 cases. The most common clinical manifestations were non-productive cough (82%), progressive dyspnea (82%) and crepitation (27%). The most common extrathoracic manifestations of MPA in patients with ILD were glomerulonephritis with decreased renal function (91%), fever (100%) and arthritis (91%). All patients received induction therapy with glucocorticosteroids combined with cyclophosphamide, rituximab, azathioprine or methotrexate.Abstract aB0631 Table 1. Characteristics of patients with MPA and ILD n = 11 Male gender, n (%) 7 (64) Age of the onset of ILD, Me, IQR, years 55 [53; 63] Age of the onset of MPA, Me, IQR, years 59 [54; 65] ILD onset Before systemic manifestations of MPA, n (%) 5 (45) At MPA onset, n (%) 6 (55) ANCA specificity MPO-ANCA, n (%) 6 (55) PR3-ANCA, n (%) 2 (18) unidentified aNCA, n (%) 3 (27) Clinical symptoms Fatigue, n (%) 11 (100) Fever, n (%) 11 (100) Weight loss, n (%) 4 (36) Arthralgia, n (%) 10 (91) Skin vasculitis, n (%) 5 (45) Renal manifestations, n (%) 10 (91) Ear, nose and throat involvement, n (%) 4 (36) Chronic cough, n (%) 9 (82) Hemoptysis, n (%) 2 (18) Dyspnea, n (%) 9 (82) Crackles, n (%) 3 (27) Laboratory and instrumental findings Increasing of ESR and/or CRP, n (%) 10 (91) Anemia, n (%) 7 (64) 24-hours proteinuria, g/day 0.61 [0.25; 1.95] Estimated GFR, ml/min/1.73 m2 39 [19; 60] Radiological patterns UIP, n (%) 3 (27) NSIP, n (%) 5 (45) Unclassified IP, n (%) 3 (27) Mediastinal lymphadenopathy, n (%) 3 (27) Emphysema, n (%) 2 (18) Remission induction therapy Glucocorticosteroids, n (%) 11 (100) Cyclophosphamide, n (%) 7 (64) Rituximab, n (%) 1 (9) Azathioprine, n (%) 1 (9) Methotrexate, n (%) 1 (9) Conclusion: ILD is a rare manifestation of MPA, which can precede systemic manifestations. ANCA-associated vasculitis should be included in the spectrum of differential diagnosis in patients with ILD. Disclosure of interests: None declared