The most accurate and reliable way to diagnose malignant tumors is pathological diagnosis. Even if it looks like a tumor on ultrasound, CT or MRI, it is not guaranteed that 100% of them are malignant tumors. Moreover, sometimes benign diseases such as inflammatory pseudotumors and hemangiomas cannot be distinguished from malignant tumors on imaging. Therefore, to confirm the diagnosis of tumor, final pathological diagnosis is needed, which can be obtained through ultrasound or CT-guided puncture biopsy, or direct surgical resection. If it is lung cancer, pathology can be taken through bronchoscopy. If it is gastrointestinal malignant tumor such as esophageal cancer, gastric cancer, colorectal cancer, most of them can be biopsied and sent to pathology through endoscopy.