IgG4-related disease: description of a case with pulmonary lesions, mediastinal lymphadenopathies and rapidly progressive renal failure.

This is a case report of a 73-year-old man with new-onset acute renal failure while being investigated for pulmonary infiltrates and mediastinal lymphadenopathies. Urine tests showed tubular range proteinuria with no microhaematuria. Immunology tests showed elevated serum IgG and hypocomplementaemia (classical pathway activation). Renal biopsy and clinical-pathological correlation were crucial in this case, reinforcing their important role in the final diagnosis of acute kidney injury.