Pneumonia-Masked Pulmonary Embolism in Nephrotic Syndrome: Diagnostic Value of V/Q Scintigraphy: A Case Report

<b>Background and Clinical Significance:</b> Nephrotic syndrome predisposes patients to venous thromboembolism. This case highlights the challenges of diagnosing pulmonary embolism in nephrotic syndrome patients with renal dysfunction, and emphasizes the utility of ventilation-perfusion lung scintigraphy when the contrast is contraindicated. <b>Case Presentation:</b> A 52-year-old male presented with fatigue, left back pain, dyspnea, and lower limb edema. The laboratory findings indicated nephrotic syndrome with significant proteinuria, hypoalbuminemia, and impaired renal function. Elevated inflammatory markers and lung infiltrates on chest CT suggested pneumonia. Despite antibiotic therapy, lung shadows, and elevated D-dimer persisted. Lower extremity ultrasound was negative for deep vein thrombosis. Due to concerns about contrast-associated nephropathy, ventilation-perfusion lung scintigraphy was performed, revealing a right lung base mismatch, leading to a diagnosis of pulmonary embolism and infarction. A kidney biopsy confirmed minimal change in disease. The patient achieved complete remission of nephrotic syndrome and was discharged on oral anticoagulation. His oral anticoagulation was discontinued after 3 months due to sustained remission and the absence of deep vein thrombosis. <b>Conclusions:</b> Pulmonary embolism and infarction can occur even in the absence of deep vein thrombosis. ventilation-perfusion lung scintigraphy is useful for detecting pulmonary embolism in patients with impaired renal function.