Microscopic polyangiitis as lung-kidney syndrome. Case reportort

Abstract

Introduction: Lung-kidney syndrome is a rare, severe, but highly fatal manifestation of primary systemic small-vessel vasculitis. It is characterized histologically by pulmonary and renal capillaritis and clinically by rapidly progressive glomerulonephritis. Among ANCA-associated vasculitis (AAV), a group of autoimmune diseases affecting small and medium-sized blood vessels, microscopic polyangiitis (MPA), associated with MPO-ANCA, can manifest as lung-kidney syndrome.

Case report: a 22-year-old woman with no prior medical history, presenting with a one-month history of abdominal pain, nausea, vomiting, asthenia, and hyporexia. Laboratory tests revealed anemia, acute kidney injury, hematuria, and proteinuria. Chest tomography showed bilateral pulmonary infiltrates. Renal biopsy confirmed pauci-immune extracapillary proliferative glomerulonephritis. A diagnosis of MPA with pulmonary-renal syndrome phenotype was established, and treatment was initiated with methylprednisolone and rituximab, followed by maintenance therapy with azathioprine and progressive dose reduction of prednisone.

Conclusions: early and accurate diagnosis of AAV is crucial for proper management and prognosis. The combination of glucocorticoids and immunosuppressants significantly improves survival and disease remission. This case highlights the importance of a multidisciplinary approach and the use of biomarkers for the rapid identification and treatment of MPA.