A Young Man with an Unusual Pulmonary-Renal Syndrome

Introduction: Pulmonary-renal syndrome commonly denotes an autoimmune disease characterized by pulmonary capillaritis and crescentic glomerulonephritis. Rarely, pulmonary-renal syndrome is from non-immune causes such as infections and heart failure. We report a rare cause of pulmonary-renal syndrome in a young man from Boston. Case Description: A 27-year-old man from Boston presented with 1 week of fever, headaches, non-productive cough, and 1 day of dyspnea. He vaped nicotine and kratom and swam regularly in freshwater ponds for recreation. There were occasional rats noted at home. Physical examination was only remarkable for respiratory distress with hypoxia without hypotension or hypertension. Chest X-ray showed bilateral reticulonodular opacities. Sulfamethoxazole-trimethoprim and oral prednisone (40 mg twice daily) were started on day 1, considering pneumocystis jiroveci pneumonia. Doxycycline was started as the patient was exposed to pond water and rodents. Serum creatinine was 1.74 mg/dL on presentation and increased to 5.46 mg/dL over 72 hours with preserved urine output. Urine microscopy revealed numerous red and white blood cells without casts. On day 2, he developed one episode of hemoptysis and worsening hypoxia, requiring mechanical ventilation. Bronchoscopy was suggestive of diffuse alveolar hemorrhage (DAH). Intravenous methylprednisolone pulse 1 g daily and daily plasma exchange were then started, considering vasculitis (pulmonary-renal syndrome). ANCA and anti-GBM antibodies returned negative on day 5, and plasma exchange was stopped. Urine for leptospira PCR, sampled on admission, was reported positive on day 10. Microbiological tests were negative. The patient received doxycycline for seven days and cefepime for five days. Fever resolved in the first week of hospitalization. Kidney function, liver function, and platelets normalized within one week. Steroids were tapered and stopped after day 6. The patient was extubated on day 10. The final diagnosis was a leptospirosis-induced pulmonary-renal syndrome with hepatic and hematologic involvement. Discussion: Leptospirosis is increasingly reported in the United States, especially in urban areas at risk of rodent exposure. It can present with severe kidney involvement and pulmonary hemorrhage with or without icterus. A high index of suspicion is crucial to reach the diagnosis in non-endemic regions.