Unusual appearance of perirenal fibrosis in renal cell carcinoma simulating a tumour

Recurrent renal cell carcinoma manifesting as a large intrathoracic fibrotic mass: A case report

Renal cell carcinomas (RCCs) have a strong tendency to metastasize, and the most common sites are the lungs, bones and liver. Late recurrence is another feature of the RCC, with lesions appearing ≥10 years after surgical treatment. However, fibrosis has rarely been associated with the disease. The present study reports a case of recurrent RCC that manifested as a fibrotic mass within the thorax. A 48-year-old man presented with dyspnea that had persisted for 3 days. The patient had undergone a right radical nephrectomy for stage II clear cell carcinoma of the kidney 6 years previously. The patient was a current smoker, with a smoking history of 20 pack-years. Chest radiography showed pleural effusion in the right thorax with an egg-sized mass shadow within the right upper lung (RUL) field. Computed tomography (CT) showed a main mass, 7 cm in diameter, within the RUL, with heterogeneous enhancement and multiple nodules of various sizes in the lungs, suggestive of primary lung cancer or metastatic RCC. A CT-guided percutaneous needle aspiration biopsy was obtained from the main mass, but histology revealed dense fibrous tissue without any malignant cells. Positron emission tomography-CT demonstrated an irregular hypermetabolic RUL mass, with a standardized uptake value (SUV) of 5.0, along the right pleura, and small pulmonary nodules (SUV, 2.0). Ultrasound-guided biopsy was attempted for a smaller hypermetabolic pleural nodule and the result was clear cell adenocarcinoma, consistent with the previous renal histology. The present study describes the case, along with a review of the relevant literature.