[The acute pulmonary renal syndrome: An unusual presentation of granulomatosis with polyangiitis].

Introduction: We report a case of acute pulmonary renal syndrome mimicking septic shock, which led to the diagnosis of granulomatosis with polyangiitis.

Case Report: A 70-year-old man was hospitalized because of acute kidney injury and acute respiratory distress syndrome with diffuse alveolar hemorrhage associated with a serum procalcitonin level of 18 μg/L. Initially, septic shock was suspected and antibiotic therapy was started. The absence of microbiological isolates and the patient's rapid clinical deterioration prompted laboratory testing for autoimmune disease, which confirmed the diagnosis of granulomatosis with polyangiitis. Immunosuppressive therapy was promptly initiated with corticosteroids, cyclophosphamide and several plasma exchanges, which resulted in a rapid clinical improvement and ICU discharge.

Conclusions: Granulomatosis with polyangiitis is a systemic necrotizing vasculitis with antineutrophil cytoplasmic antibodies, which can present with acute pulmonary renal syndrome, combining acute respiratory distress syndrome and acute kidney injury. This misleading presentation must prompt an autoimmune disease testing in order to yield an early diagnosis of a vasculitis, allowing for timely initiation of immunosuppressive treatment. Serum procalcitonin levels can be markedly elevated and this must not override the possibility of a vasculitis where the patient shows a compatible symptomatology.