Oncogenic fusion in rare subtype of small intestine metastasis from occult lung cancer.

We present the case of a 66-year-old male patient who was found to have a lung nodule during the perioperative period for poorly differentiated carcinoma of the ileocecal region. Subsequent surgical procedures were performed to remove the intestinal and lung masses. Next-generation sequencing (NGS) testing demonstrated that the intestinal and lung lesions exhibited the same pathogenic fusion. Following 7 months of Alectinib treatment, the patient's clinical evaluation showed stable disease. This is the first report of intestinal metastases from lung cancer with fusion. Our findings indicate that a comprehensive approach, including histopathological examination and genetic testing, is necessary to diagnose and treat intestinal metastases from lung cancer accurately.