Pulmonary Aspergillosis Mimicking Metastatic RCC: A Postnephrectomy Diagnostic Consideration

Survivors of renal cell carcinoma (RCC), especially following nephrectomy, require long follow-up for recurrence or systemic complications. While those with a history of RCC develop pulmonary nodules often with concern for metastasis, we must consider infectious diseases, especially in patients with environmental exposures and immune alterations related to metabolic changes secondary to nephrectomy. We report a 49-year-old male with a history of RCC status postnephrectomy, history of long-term smoking, and history of significant coal dust exposure, who developed progressive pulmonary nodules. Although initially suspected to be metastatic RCC (mRCC), serial imaging demonstrated nodule enlargement without metabolic activity on PET scan, requiring further evaluation. Given the persistent respiratory symptoms, he underwent bronchoscopy with microbiologic analysis which identified <i>Aspergillus fumigates</i> and was ultimately diagnosed with chronic pulmonary aspergillosis. Our patient was successfully treated with voriconazole and over time demonstrated significant clinical improvement. In this case, we have made the observation of the diagnostic dilemma presented by the pulmonary nodules in RCC survivors and the importance of a broad differential to avoid misdiagnosis. Immune changes following nephrectomy, possible accompanying chronic kidney disease (CKD), or prolonged oncologic surveillance could place patients at risk for opportunistic infections. In order to ensure timely detection and treatment of infections that may mimic tumor progression, clinicians treating RCC survivors should integrate microbiologic diagnostics into routine pulmonary evaluations.