The unusual case of an adenocarcinoma of the caecum undiagnosed until the appearance of a large neck and axillary mass is reported. To our knowledge, this is the first reported case of cervical node metastasis as the first sign of a caecal cancer, and 18 fluorine-18-labeled 2-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) proved critical in achieving the correct diagnosis. When an adenocarcinoma is found in the neck or axilla, even an abdominal primary location such as the large bowel can be taken into account and employment of FDG-PET should be considered.