Rationale:Xanthogranulomatous pyelonephritis (XGPN) is a form of chronic pyelonephritis caused by chronic calculus obstruction and bacterial infection, leading to the destruction of the renal parenchyma and calyces. Conservative treatment is usually not sufficient, and surgical intervention is still the main curative approach. XGPN with transdiaphragmatic extension and lung abscess formation is a rare condition.Patient concerns:We report a 64-year-old woman who presented with persistent productive cough.Diagnoses:Lung abscess secondary to XPGN. Both nephrostomy urine and sputum cultures showedProteus mirabilisinfection with the same antibiotic sensitivity spectrum, but blood culture was negative.Interventions:Laparoscopic radical nephrectomy and prolonged antibiotic treatment.Outcomes:The lung abscess and cough gradually resolved in 1 month after nephrectomy.Conclusion:Lung abscess secondary to transdiaphragmatic extension of XGPN is rare but should be considered in patients with lower lung infections that are unresponsive to treatment, especially infections due to unusual respiratory pathogens such asP mirabilis.