LAUSR

The development of distant metastases is a common feature of renal cell carcinoma (RCC). Even after nephrectomy of a locally confined tumour, more than 30% of patients develop metastases, with lungs being the most common target of secondary lesions. Late recurrence of metastatic RCC up to 45 years later has been reported. Herein, we report a case of 18-F fluorodeoxyglucose positron emission tomography (FDG PET)-negative pulmonary nodules that were found to be metastatic RCC 18 years following curative surgery. A 62-year-old man presented with a 3-week history of cough and fevers and a chest computed tomography (CT) showing multiple lung nodules in both lower lobes (Fig. 1A). He never smoked. Eighteen years before the present evaluation, the patient had an incidental CT finding of a 4.5-cm right kidney mass. He underwent a radical nephrectomy and histopathology revealed clearcell RCC. The tumour was well demarcated and largely encapsulated. No vascular invasion was seen. The tumour was Fuhrman nuclear Grade 2 (of 4). There was no evidence of capsular penetration and little infiltration of the surrounding renal parenchyma. He was followed up with annual CT scans over the next 10 years and had no signs of recurrence. Presently, the patient underwent FDG PET, which revealed no significant uptake in the renal bed or the pulmonary nodules (Fig. 1B). The patient proceeded with percutaneous lung biopsy. The histopathology revealed nests and trabeculae of cells with clear cytoplasm and mildly variable nuclei interspersed by mildly dilated thin-walled vessels (Fig. 1C). Immunohistochemistry showed that the tumour cells were positive for pancytokeratin and PAX8 and negative for TTF1 and PSA. The final diagnosis was therefore metastatic RCC.