Pneumorenal Syndrome Complicating ANCA-Negative Pauci-Immune Vasculitis Associated with Atypical Mycobacteriosis: Case Report

Among the forms of pneumorenal syndrome (PRS), one of the most urgent is characterized by the combination of diffuse alveolar hemorrhage and rapidly progressive glomerulonephritis (RPGN). In 90% of cases, it is the manifestation of an autoimmune disease, such as pauci-immune vasculitis with anti-neutrophil cytoplasmic antibodies (ANCA) or Goodpasture's disease with the presence of antibodies directed against the basement membrane of the glomerular and alveolar capillaries (anti-GBM). These antibodies are absent in approximately 10% of cases with histological confirmation in the context of rare clinical situations. We report a case of a 66-year-old patient, with a history of alcoholism and active smoking, who was admitted to the hospital for respiratory distress with hemoptysis. The admission assessment showed severe renal failure requiring hemodialysis upon admission. ANCA and anti-GBM, as well as all other autoantibodies were negative. A renal biopsy revealed pauci-immune extra-capillary glomerulonephritis with the majority of chronic lesions. The orientation of the diagnostic approach in search of other causes of pauci-immune vasculitis with negative antibodies has been initiated. He was treated with glucocorticoids in combination with cyclophosphamide. The initial evolution was marked by the improvement of respiratory symptoms and a less considerable recovery of renal function. PRS can develop without the presence of ANCA or other autoantibodies. The diagnosis is then made by histology. Renal damage, such as extra-capillary glomerulonephritis (GN), is more severe and has a very poor prognosis with a high risk of mortality. The absence of ANCA should never delay diagnosis and treatment.