A silent journey from kidney to lungs: pyelonephritis triggering septic pulmonary embolism - a rare case report from Nepal.

Introduction: Septic pulmonary embolism (SPE) is a rare, life-threatening condition caused by infected thrombi from extrapulmonary sites lodging in pulmonary arteries, resulting in infarction and infection. Its nonspecific presentation, including fever, cough, and chest pain, often delays diagnosis. Predisposing factors include infective endocarditis, intravascular catheters, oropharyngeal infections, and urinary tract infections. Case presentation: A 68-year-old female with hypertension and diabetes mellitus arrived with fever, active cough, sudden shortness of breath, and pain in her left flank. The chest computed tomography (CT) revealed bilateral lung nodules with cavitation, wedge-shaped opacities, and feeding vessel indications, all of which were suggestive of SPE. Laboratory tests revealed leukocytosis and increased C-reactive protein. Clinical discussion: SPE diagnosis is difficult due to vague symptoms, but can be supported by CT findings such as peripheral nodules, cavitation, wedge-shaped lesions, and feeding vessel indications. Early identification of the major illness source and the use of targeted broad-spectrum antibiotics are crucial. Differential diagnoses include tuberculosis, cancer, necrotizing pneumonia, and fungal diseases; fast cavitation and peripheral spread favor SPE. Conclusion: SPE should be suspected in patients with extrapulmonary infections presenting with pulmonary nodules or cavitation, particularly when CT shows feeding vessel signs. Prompt diagnosis, removal of infectious sources, and early, appropriate antibiotic therapy are essential to improve patient outcomes.