The most common metastatic sites for colorectal carcinomas include the liver, lungs, brain, bones and peritoneal surfaces. In this report, a case of sigmoid colon carcinoma presented with cervical lymphadenopathy was detected with the help of PET/CT. A 57 year-old male presented with a complaint of swelling on the left side of his neck. Ultrasonographic examination of the neck revealed three hypoechoic, peripherally vascularized lymph nodes with the largest diameter of 3cm. The thyroid gland was normal. Fine needle aspiration biopsy was performed and the pathology result was a metastatic carcinoma. He underwent a PET/CT scan to search for the primary carcinoma which showed increased standardized uptake value of 13.2 in the left colon and 10.8 in the left cervical region. Colonoscopy showed an ulcerated mass lesion with obstruction of the lumen in the sigmoid colon.The patient had an anterior resection of the sigmoid colon with simultaneous resection of cervical lymph nodes. There was no evidence of intra-abdominal dissemination during surgery. The lymph nodes removed from the neck were also reportedas metastatic adenocarcinoma. The patient underwent six cycles of adjuvant FOL FOX chemotherapy regimen. The patient has remained disease free after nine months of follow-up. PET/CT was a quick, effective method for the detection of the primary tumor in the sigmoid colon. In additional to colonic resection and systemic therapy, palliative local control can also be achieved with the excision of metastatic lymph nodes in the neck.