P031 Montelukast antagonising underlying systemic illness

Abstract Background/Aims Eosinophilic granulomatosis with polyangiitis (EGPA) is a rare, multisystemic, autoimmune vasculitis involving small to medium-sized blood vessels. It has well-established affiliation atopic syndromes, typically adult-onset asthma and sinusitis. More rare associations are linked drug side effects such as Montelukast. According the ‘American College of Rheumatology 1990’, following criteria yield sensitivity 84% in identifying patient EGPA. The include: asthma, eosinophilia >10% on differential white cell count, mononeuropathy or polyneuropathy, transient pulmonary infiltrates chest radiography, paranasal sinus abnormality, vessel biopsy demonstrating extravascular eosinophilia, symptoms systemic vasculitis. multisystemic involvement EGPA makes both diagnosis management difficult presentations can vary. Methods We report complex case 61 year-old gentleman diagnosed His relevant past medical history includes Asthma 2002 (managed inhaled bronchodilators, corticosteroids, montelukast), recurrent sinusitis, lower respiratory tract infections. presented one month abdominal cramping bloating. This was associated nausea, constipation, anorexia, week ‘drenching’ night sweats. full physical examination during this time unremarkable. Results He had normal CT Abdomen Pelvis colonoscopy. admission radiograph demonstrated bilateral parenchymal lung changes. followed by Thorax showing upper lobe bronchiectasis. Mediastinal hilar adenopathy consistent allergic bronchopulmonary aspergillosis reactive adenopathy. laboratory investigations showed (21.68) leucocytosis (32.7). In view these results, an autoantibody screen sent positive ANCA anti-Myeloperoxidase antibodies(MPO titre 55). Two days into his he developed pain paralysis right limb. reported marked fatigue petechial, non-blanching, vasculitic rash ankles. Neurological reflected subacute symmetrical sensory motor polyneuropathy predominantly foot drop. MRI Brain established infarct left external capsule. commenced high dose aspirin. Due suspicion for EGPA, methylprednisolone 5 days, tapering oral corticosteroid therapy Rituximab therapy. A skin punch ‘ vasculopathic type reaction vasculitis, mixed inflammatory infiltrate which some eosinophils’ confirmed diagnosis. Conclusion topic particular relevance association between montelukast. been hypothesised that there may be relationship Leukotriene Receptor Antagonist Therapy, specifically Montelukast, pathogenesis Some research suggests treatment Montelukast permits decreased need corticosteroids control. Therefore, suggesting could have masked Disclosure Á. Connerton: None.