Unexpected small bowel intussusception caused by lung cancer metastasis on 18F-fluorodeoxyglucose PET-CT.

Small bowel metastasis from primary lung cancer is rare. We report the case of an unexpected small bowel intussusception caused by primary non-small cell lung cancer, which was primarily detected by 18 fluorine ((18)F)-fluorodeoxyglucose (FDG) positron emission tomography (PET) and computed tomography (CT). A 74-year-old man underwent FDG PET-CT for the diagnostic workup of a lung mass in the left upper lobe. On FDG PET-CT images, intense FDG uptake was observed in the primary lung mass lesion and mediastinal paraesophageal area. Furthermore, unexpected intense FDG uptake was observed in the jejunum along with the findings of intussusception in the proximal jejunum on the CT images of the PET-CT, which suggested jejunojejunal intussusception caused by lung cancer metastasis. The patient underwent an immediate operation, and the histopathologic results of the resected bowel indicated metastatic lesion from adenocarcinoma of the lung.