Pulmonary fibrosis and microscopic polyangiitis in a 75-year-old woman

We present a case of a 75-year-old woman who admitted in the internal medicine department for a recent onset of persisting moderate daily fever and fatigue that started 30 days prior to her hospitalization. Her past medical history is remarkable for mild pulmonary fibrosis, megaloblastic anaemia, and hypergammaglobulinaemia of no obvious causes. On presentation, she was febrile (38°C) and had high ESR and CRP levels, but most of her laboratory tests were within normal levels and had no signs of arthritis or rash. She was hospitalized for suspected lower urinary tract infection and started on antibiotics. During hospitalization, her renal function deteriorated together with microscopic haematuria, proteinuria and granular urine casts in urine analysis and her inflammation markers raised further. A renal biopsy revealed glomerulonephritis with pauci-immune crescents, and serology tests were positive for anti-MPO p-ANCA, both suggesting a diagnosis of microscopic polyangiitis (MPA). While high-dose methylprednisolone pulses and cyclophosphamide were introduced intravenously, there was no remission, but respiratory failure occurred that led to patient's intubation and transfer to the ICU. She died a few days later due to septic shock. Asymptomatic pulmonary fibrosis can precede microscopic polyangiitis for several years and is associated with a poor prognosis.