Endobronchial metastasis secondary to renal clear cell carcinoma: A case report.

Background: Endobronchial metastases (EBMs) are tumours that metastasise from a malignant tumour outside the lungs to the central and subsegmental bronchi, and are visible under a bronchofibrescope. Most EBMs are formed by direct invasion or metastasis of intrathoracic malignant tumours, such as lung cancer, oesophageal cancer or mediastinum tumours. Renal cell carcinoma (RCC), accounting for 2% to 3% of all tumours, is a common malignant tumour of the urinary system. Renal clear cell carcinoma (RCCC) constitutes the predominant pathological subtype of RCC, comprising approximately 70% to 80% of all RCC cases. RCCC can spread and metastasise through arterial, venous and lymphatic circulation to almost all organs of the body. Moreover, lung, bone, liver, brain and local recurrence are the most common metastatic neoplasms of RCCC. However, EBM from RCCC has a low complication rate and is often misdiagnosed as primary lung cancer.

Case Summary: A 71-year-old male patient who had undergone radical left nephrectomy 7 years prior due to RCCC was referred to our hospital due to a 1-mo history of productive cough. The results of an enhanced chest CT scan indicated the presence of a soft tissue nodule in the upper lobe of the left lung, and flexible bronchoscopy revealed a hypervascular lesion in the bronchus of the left lung's superior lobe. Therefore, the patient underwent thoracoscopic left superior lobe wedge resection, and pathology confirmed EBM from the RCCC.

Conclusion: EBM from RCCC has a low incidence and no characteristic clinical manifestations in the early stage. If a bronchial tumour is found in a patient with RCCC, the possibility of bronchial metastatic cancer should be considered.