Goodpasture's syndrome with absence of circulating anti-glomerular basement membrane antibodies: a case report.

BACKGROUND: Goodpasture's syndrome, a rare disease, is an organ-specific autoimmune disease mediated by anti-glomerular basement membrane antibodies. Its pathology is characterized by crescentic glomerulonephritis with linear immunofluorescent staining for immunoglobulin G on the glomerular basement membrane. Although rare, a few cases with absence of circulating anti-glomerular membrane antibodies have been described.

CASE PRESENTATION: The objective of this clinical case report is to describe and discuss a case of a 27-year-old white man who was hospitalized with a 1-year history of weight loss and a 1-month history of hemoptysis, with aggravation  the day before, having developed dyspnea and cough in the previous 24 hours. An analytical study showed normocytic normochromic anemia with a hemoglobin level of 7.2 g/dL and leukocytosis with normal renal function and coagulation times. A blood transfusion was performed without complications. Chest computed tomography revealed a reticulonodular infiltrate of both lungs. Bronchoscopy showed no apparent lesions. Sputum cultures, rapid urine antigens for Legionella pneumophila and Streptococcus pneumoniae, studies for Influenza, virologic markers and serologic studies for autoimmunity were all negative. At the end of the tenth day his general state deteriorated with fatigue, hematuria, and in 3 days he developed aggravation of renal function with recurrent hemoptysis and anemia. Immunosuppression with daily prednisolone 1 g administered intravenously was initiated. An urgent bronchoscopy showed no lesions. A kidney biopsy showed fibrinoid necrosis and cellular crescents. Immunofluorescence revealed a linear immunoglobulin G deposition compatible with Goodpasture's syndrome. Immunosuppressive therapy with daily cyclophosphamide 120 mg orally was added. Subsequently he was transferred to a referral center at which 21 sessions of plasmapheresis and four sessions of hemodialysis were performed with good response; he currently has no need of hemodialysis.

CONCLUSIONS: The absence of circulating anti-glomerular basement membrane antibodies in Goodpasture's syndrome adds complexity to the diagnosis creating an unusual setting in a rare disease. In our case a kidney biopsy was essential for diagnosis and clinical approach. Studies have shown that early aggressive therapy leads to an improved prognosis. Physicians should consider tissue diagnoses such as bronchoscopy and kidney biopsy in pulmonary renal syndrome.