Abstract MPO ANCA-associated vasculitis (AAV) is a small vessel vasculitis characterized by systemic necrotizing vasculitis with few or no immune deposits. It primarily involves the kidneys and lungs. We present the case of a 35-year-old female with a prior diagnosis of dermatomyositis (DM) interstitial lung disease, not on immunosuppressants, presenting with acute renal failure and eventually diagnosed overlap MPO-AAV/DM. She initially presented with shortness of breath and leg swelling and was found to be in acute hypoxic respiratory failure requiring intubation. Labs showed evidence of acute renal failure with a creatinine of 9, and inflammation with CRP of 2300. A CT chest was performed which showed evidence of bilateral ground glass opacities suggestive of volume overload with a component of flare up of her underlying lung disease. The patient was started on CRRT and received 1g of methylprednisolone daily for 3 days. Over the next 36 hours, she had rapid improvement and was extubated and transitioned to hemodialysis. Given the concomitant renal and pulmonary involvement, a repeat autoimmune workup was sent which was noted for positive P-ANCA MPO serologies, raising suspicion for overlap syndrome of MPO AAV and DM. She underwent kidney biopsy which showed evidence of rapidly progressive crescentic glomerulonephritis consistent with AAV. She was induced with rituximab and transitioned to a prednisone taper. Pulmonary-renal syndromes (PRS) encompass disease processes characterized by life-threating diffuse alveolar hemorrhage and rapidly progressive glomerulonephritis. The differential of PRS includes anti-glomerular basement membrane disease, ANCA vasculitis, IgA disease, cryoglobulinemia, and connective tissue disease. The different forms of AAV include Microscopic polyangiitis, Granulomatous polyangiitis, and eosinophilic granulomatous polyangiitis. The classification criteria of Microscopic polyangiitis include pauci immune GN on kidney biopsy, fibrosis or interstitial lung disease on imaging, positive ANCA serologies or MPO serologies, and lastly nasal involvement observed on physical examination. Our patient presented with acute hypoxic respiratory failure and acute renal failure which are not concomitantly typical manifestations of DM which prompted the evaluation for PRS, and that led to the diagnosis of MPO AAV. We conducted a review of the literature which showed in one study of 12 patients that the incidence of overlap syndrome of MPO AAV and DM was as high as 75%. This highlights the importance of maintaining a broad differential diagnosis in a patient presenting with PRS, and the possibility of two coexisting rare diagnoses. This abstract is funded by: N/A
Hinojosa et al. (Fri,) studied this question.